46 results on '"Raul Laguzzi"'
Search Results
2. Activation of nucleus tractus solitarius 5-HT2A but not other 5-HT2 receptor subtypes inhibits the sympathetic activity in rats
- Author
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Caroline Sévoz-Couche, Raul Laguzzi, Jean-François Bernard, M.-A. Comet, and Michel Hamon
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Agonist ,medicine.drug_class ,Chemistry ,General Neuroscience ,5-HT2 receptor ,Rostral ventrolateral medulla ,Baroreflex ,Pharmacology ,Receptor antagonist ,nervous system ,Anesthesia ,medicine ,Serotonin ,Receptor ,Microinjection ,circulatory and respiratory physiology - Abstract
Our first aim was to elucidate the mechanisms underlying the hypotensive response elicited by 5-HT(2) receptor activation in the nucleus tractus solitarius (NTS). In pentobarbitone-anaesthetized rats, intra-NTS administration of 2,5-dimethoxy-4-iodoamphetamine (DOI), a wide spectrum 5-HT(2) receptor agonist, but not an antagonist of selective 5-HT(2B) and 5-HT(2C) receptors, produced a decrease in blood pressure and heart rate. The maximal cardiovascular changes obtained by DOI (0.5 pmol) could be almost completely abolished by prior intra-NTS microinjection (10 pmol) of MDL-100907, a selective 5-HT(2A) receptor antagonist, but not by 5-HT(2B) or 5-HT(2C) receptor antagonists. In addition, using extracellular recordings we found that the large majority of identified cardiovascular rostroventrolateral medulla (RVLM) neurons were almost totally inhibited by NTS 5-HT(2A) receptor stimulation. We then investigated whether intra-NTS administration of a subthreshold dose (0.05 pmol) of DOI, known to facilitate the cardiovagal component of the baroreflex, could also modulate the sympathoinhibitory component of this reflex. These experiments showed that neither the decrease in the activity of the cardiovascular RVLM neurons and lumbar sympathetic nerve activities produced by aortic occlusion (gain of the baroreflex), nor the hypotensive response elicited by aortic nerve stimulation, were potentiated by the microinjection of DOI under such conditions. These data show that activation of 5-HT(2A), but not 5-HT(2B) or 5-HT(2C), receptors, located on NTS neurons, elicits depressor and bradycardic responses, and that this 5-HT(2A)-mediated hypotension is produced via the inhibition of RVLM cardiovascular neurons. In addition, NTS 5-HT(2A) receptor activation facilitates the cardiac but not the sympathetic baroreflex response.
- Published
- 2007
3. The Key Role of Medullary 5-HT3 Receptors in the Serotonin-Mediated Neural Control of Cardiovascular Function
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B H Machado, Caroline Sévoz-Couche, Martial Hamon, and Raul Laguzzi
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Pharmacology ,Baroreceptor ,GABAA receptor ,Central nervous system ,Glutamate receptor ,Stimulation ,General Medicine ,Biology ,Serotonergic ,Psychiatry and Mental health ,medicine.anatomical_structure ,nervous system ,Neurology ,medicine ,Pharmacology (medical) ,Neurology (clinical) ,Serotonin ,Receptor ,Neuroscience ,circulatory and respiratory physiology - Abstract
The baroreceptor reflex plays a crucial role in the homeostatic control of cardiovascular parameters. In the central nervous system, the nucleus of the tractus solitarius (NTS) is critically involved in cardiovascular reflex control because it is both the first site of termination of glutamatergic baroreceptor afferent fibres and an important integrative area for the sensory afferent signals reaching the brainstem. In addition to glutamate, the NTS contains numerous neurotransmitters that could participate in the modulations of the baroreceptor reflex sensitivity which occur under various physiological conditions. In particular, a large body of evidence indicates that serotonin plays a modulatory role in the central control of blood pressure, especially at the level of the NTS, which is innervated by both central and peripheral serotonergic fibres. Indeed, serotonin exerts multiple cardiovascular influences through the activation of several receptors in the NTS. Actually, the NTS is the central area endowed with the highest density of serotonin3 (5-HT3) receptors whose stimulation triggers all the adaptive cardiovascular changes normally associated with behavioural responses to various stressful conditions. In this review, we first assess the current knowledge about the mechanisms underlying the cardiovascular effects of the specific activation of serotonergic receptors in the NTS. Secondly, we describe evidence that, in the NTS, 5-HT3 receptors play a key role in one of the crucial homeostatic responses that characterise the defence reaction: the inhibitory modulation of the parasympathetic cardiac component of the baroreceptor reflex. The possible functional interactions of 5-HT3 receptors with GABAA, NK1 and NMDA receptors within the NTS are also discussed.
- Published
- 2005
4. Functional interaction between nucleus tractus solitarius NK and 5-HT receptors in the inhibition of baroreflex in rats
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Raul Laguzzi, Caroline Sévoz-Couche, Martial Hamon, and Marie-Anne Comet
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medicine.medical_specialty ,Baroreceptor ,Physiology ,Chemistry ,musculoskeletal, neural, and ocular physiology ,Solitary nucleus ,Stimulation ,Baroreflex ,Endocrinology ,nervous system ,Physiology (medical) ,Internal medicine ,Reflex bradycardia ,cardiovascular system ,medicine ,Cardiology and Cardiovascular Medicine ,Receptor ,Phenylephrine ,circulatory and respiratory physiology ,medicine.drug ,Phenylbiguanide - Abstract
Objective : Previous data showed that in the nucleus tractus solitarius (NTS), 5-HT3 receptors are critically involved in the inhibition of cardiac baroreceptor reflex response occurring during the defense reaction. Since stimulation of NTS NK1 receptors has been found to inhibit the baroreflex bradycardia, we examined in this study whether this reflex response is inhibited during the defense reaction via an interaction between NK1 and 5-HT3 receptors. Methods : For this purpose, we analyzed in urethane-anaesthetized rats the effects of intra-NTS GR205171, a selective NK1 receptor antagonist, on the baroreflex bradycardia inhibition observed either during the defense reaction triggered by electrical stimulation of the dorsal periaqueductal grey matter (dPAG) or after NTS 5-HT3 receptor activation. Results : Intra-NTS GR205171, reversed, in dose-dependent manner, the inhibitory effect of dPAG stimulation on baroreflex bradycardia. This reversion was of 49% when both sinus carotid and aortic baroreceptors were stimulated by phenylephrine, and of 84% when aortic depressor nerve was stimulated. Similarly, intra-NTS GR205171 reversed partially or almost totally the inhibitory effect of local microinjections of phenylbiguanide, a 5-HT3 receptor agonist, on baroreflex bradycardia induced either by phenylephrine administration or aortic nerve stimulation, respectively. Conclusion : These results strongly suggest that NK1 receptors contribute downstream to the 5-HT3 receptor-mediated inhibition of the aortic but not carotid cardiac baroreflex response occurring during the defense reaction, therefore implying that baroreceptor afferent inputs may be differentially modulated depending on their origin. This differentiation may be useful for a better understanding of baroreflex dysfunction in disease-induced conditions.
- Published
- 2005
5. Antinociceptive effect of cardiopulmonary chemoreceptor and baroreceptor reflex activation in the rat
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Michel Hamon, Raul Laguzzi, and Caroline Sévoz-Couche
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Atropine ,Male ,Tail ,medicine.medical_specialty ,Baroreceptor ,Chemoreceptor ,Biguanides ,Baroreflex ,Kynurenic Acid ,Rats, Sprague-Dawley ,Veratrine ,Phenylephrine ,Internal medicine ,Solitary Nucleus ,medicine ,Animals ,Sympathomimetics ,Aorta ,Analgesics ,Chemistry ,Nociceptors ,Parasympatholytics ,Chemoreceptor Cells ,Electric Stimulation ,Rats ,Anesthesiology and Pain Medicine ,Endocrinology ,nervous system ,Neurology ,Bezold–Jarisch reflex ,Reflex bradycardia ,Reflex ,Neurology (clinical) ,Skin Temperature ,Excitatory Amino Acid Antagonists ,circulatory and respiratory physiology ,Phenylbiguanide ,medicine.drug - Abstract
The effect on the nociceptive tail-flick (TF) reflex of cardiopulmonary chemoreceptor and arterial baroreceptor activation, producing Bezold-Jarisch like- and baro-reflex responses, respectively, was analysed in lightly halothane-anaesthetized rats. Intra-cardiac administration of phenylbiguanide (5-100 microg/kg, into the right atrium) or veratrine (30-150 microg/kg, into the left ventricle), which both elicited the characteristic Bezold-Jarisch-like cardiovascular reflex responses (hypotension and bradycardia), produced a dose-dependent increase in TF latency. A similar inhibitory influence on the TF reflex was noted upon baroreflex activation by acute administration of phenylephrine (15-50 microg/kg i.v.) or aortic depressor nerve stimulation (100-400 microA). As expected from the involvement of local excitatory amino acid receptors in both vagally mediated cardiovascular reflex responses and inhibition of the TF reflex, microinjections of kynurenic acid (3 nmol/0.1 microl), an N-methyl-D-aspartate (NMDA) and non-NMDA receptor antagonist, into the nucleus tractus solitarius, prevented the cardiovascular responses as well as the concomitant increase in TF latency produced by cardiopulmonary chemoreceptor and baroreceptor stimulations. The present data show that induction of the cardiopulmonary chemoreceptor and baroreceptor reflexes produces an antinociceptive effect which can be assessed using the TF test, and that glutamate ionotropic receptors within the nucleus tractus solitarius mediate this effect.
- Published
- 2002
6. Serotonin3 receptor stimulation in the nucleus tractus solitarii activates non-catecholaminergic neurons in the rat ventrolateral medulla
- Author
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Raul Laguzzi, Leni G.H. Bonagamba, J. C. Callera, Anne Nosjean, Michel Hamon, Benedito H. Machado, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil
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Male ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Biguanides ,MESH: Rats, Sprague-Dawley ,Urethane ,Rats, Sprague-Dawley ,Catecholamines ,0302 clinical medicine ,MESH: Animals ,MESH: Tyrosine 3-Monooxygenase ,Horseradish Peroxidase ,Catecholaminergic ,Medulla Oblongata ,0303 health sciences ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,MESH: Proto-Oncogene Proteins c-fos ,Chemistry ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Rostral ventrolateral medulla ,MESH: Gene Expression Regulation ,Immunohistochemistry ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,Chloralose ,MESH: Chloralose ,Medulla oblongata ,Brainstem ,Proto-Oncogene Proteins c-fos ,MESH: Receptors, Serotonin ,medicine.medical_specialty ,MESH: Rats ,Tyrosine 3-Monooxygenase ,MESH: Receptors, Serotonin, 5-HT3 ,03 medical and health sciences ,MESH: Urethane ,MESH: Medulla Oblongata ,Internal medicine ,MESH: Catecholamines ,Solitary Nucleus ,medicine ,Animals ,MESH: Horseradish Peroxidase ,Medulla ,030304 developmental biology ,Tyrosine hydroxylase ,Solitary nucleus ,MESH: Immunohistochemistry ,MESH: Biguanides ,MESH: Male ,Rats ,Endocrinology ,Gene Expression Regulation ,Receptors, Serotonin ,Catecholaminergic cell groups ,Receptors, Serotonin, 5-HT3 ,030217 neurology & neurosurgery - Abstract
International audience; The present study was performed to determine whether or not the increased arterial pressure triggered by 5-HT(3) receptor stimulation in the nucleus tractus solitarii and underlain by a sympathoexcitation is associated with the activation of ventromedullary cells known to be involved in vascular regulation, i.e. the C1 and A1 catecholaminergic cells. For this purpose, double immunohistochemical labeling for tyrosine hydroxylase and c-fos protein was performed all along the ventrolateral medulla after microinjection of 1-(m-chlorophenyl)-biguanide, a selective and potent 5-HT(3) receptor agonist, into the nucleus tractus solitarii of alpha-chloralose/urethane-anaesthetized rats. This treatment produced a significant elevation of arterial pressure ( approximately +35 mm Hg). Concomitantly, a significant increase in the number of c-fos expressing neurons was observed in the rostral ventrolateral medulla (+63%), in particular in its most anterior part (+78%), and in the medullary region surrounding the caudal part of the facial nucleus (+91%). Retrograde labeling with gold-horseradish peroxidase complex showed that at least some of these activated c-fos expressing cells project to the spinal cord. However, the number of double-stained neurons, i.e. c-fos and tyrosine hydroxylase positive neurons, did not increase at any level of the ventrolateral medulla. In contrast, under the same alpha-chloralose/urethane anesthesia, systemic infusion of sodium nitroprusside appeared to produce a hypotension and a marked increase in the density of such double c-fos and tyrosine hydroxylase expressing cells in the rostral ventrolateral medulla and the caudal medullary region surrounding the caudal part of the facial nucleus. These data indicate that medullary catecholaminergic C1 and A1 neurons are not involved in the pressor effect elicited by 5-HT(3) receptor stimulation in the nucleus tractus solitarii. However, this 5-HT(3) receptor-mediated effect is clearly associated with the excitation of (non-catecholaminergic) neurons within the pressor region of the ventral medulla.
- Published
- 2002
7. Glutamate and NO mediation of the pressor response to 5-HT3 receptor stimulation in the nucleus tractus solitarii
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Boris Maisonneuve, Raul Laguzzi, Caroline Sévoz-Couche, and Michel Hamon
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Male ,Agonist ,Serotonin ,medicine.medical_specialty ,Indazoles ,medicine.drug_class ,Biguanides ,Glutamic Acid ,Blood Pressure ,Pressoreceptors ,AMPA receptor ,Nitric Oxide ,Receptors, Metabotropic Glutamate ,Receptors, N-Methyl-D-Aspartate ,Synaptic Transmission ,5-HT3 receptor ,Rats, Sprague-Dawley ,Internal medicine ,Reflex ,Solitary Nucleus ,medicine ,Animals ,heterocyclic compounds ,Enzyme Inhibitors ,Neurons ,Oxadiazoles ,biology ,Metabotropic glutamate receptor 5 ,Chemistry ,General Neuroscience ,Glutamate receptor ,Rats ,Serotonin Receptor Agonists ,Endocrinology ,nervous system ,Guanylate Cyclase ,Metabotropic glutamate receptor ,Receptors, Serotonin ,biology.protein ,NMDA receptor ,Nitric Oxide Synthase ,Receptors, Serotonin, 5-HT3 ,Soluble guanylyl cyclase ,Excitatory Amino Acid Antagonists ,circulatory and respiratory physiology - Abstract
The possible participation of glutamate and NO/cGMP in the pressor response to 5-HT3 receptor activation in the nucleus tractus solitarii (NTS) was investigated using selective antagonists in urethane-anaesthetized rats. Intra-NTS administration of NMDA and non-NMDA receptor antagonists, but not metabotropic glutamate receptor antagonists, markedly reduced (70%) the increase in blood pressure caused by local application of the potent 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide. The 5-HT3 receptor-mediated pressor response was also significantly attenuated by the local blockade of nitric oxide synthase and soluble guanylyl cyclase. These data suggest that ionotropic glutamate receptors and the associated NO/cGMP transduction mechanism contribute downstream to the pressor effect elicited by 5-HT3 receptor stimulation in the NTS.
- Published
- 2002
8. Activation of GABAA but not GABAB receptors in the NTSblocked bradycardia of chemoreflex in awake rats
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Anne Nosjean, João Carlos Callera, Benedito H. Machado, Leni G.H. Bonagamba, Raul Laguzzi, Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Male ,Baclofen ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Peripheral chemoreceptors ,MESH: Microinjections ,chemistry.chemical_compound ,0302 clinical medicine ,MESH: Animals ,MESH: Receptors, GABA-B ,MESH: Receptors, GABA-A ,0303 health sciences ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Muscimol ,Chemistry ,GABAA receptor ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Chemoreceptor Cells ,MESH: Baclofen ,Cardiology and Cardiovascular Medicine ,circulatory and respiratory physiology ,medicine.drug ,Agonist ,medicine.medical_specialty ,MESH: Chemoreceptor Cells ,Microinjections ,MESH: Rats ,MESH: Reflex ,medicine.drug_class ,MESH: Cardiovascular Physiological Phenomena ,GABAB receptor ,MESH: Bradycardia ,Cardiovascular Physiological Phenomena ,03 medical and health sciences ,MESH: GABA Agonists ,Physiology (medical) ,Internal medicine ,Reflex ,Bradycardia ,Solitary Nucleus ,medicine ,Animals ,Rats, Wistar ,GABA Agonists ,Microinjection ,030304 developmental biology ,MESH: Rats, Wistar ,Bicuculline ,Receptors, GABA-A ,MESH: Male ,Rats ,Endocrinology ,Receptors, GABA-B ,nervous system ,030217 neurology & neurosurgery ,MESH: Muscimol - Abstract
In the present study we analyzed effects of bilateral microinjections of muscimol (a GABAA agonist) and baclofen (a GABAB agonist) into the nucleus tractus solitarius (NTS) on bradycardic and pressor responses to chemoreflex activation (potassium cyanide, 40 μg/rat iv) in awake rats. Bilateral microinjections of muscimol (25 and 50 pmol/50 nl) into the NTS increased baseline mean arterial pressure (MAP): 119 ± 8 vs. 107 ± 2 mmHg ( n = 6) and 121 ± 8 vs. 103 ± 3 mmHg ( n= 6), respectively. Muscimol at 25 pmol/50 nl reduced the bradycardic response to chemoreflex activation 5 min after microinjection; with 50 pmol/50 nl the bradycardic response to chemoreflex activation was reduced 5, 15, 30, and 60 min after microinjection. Neither muscimol dose produced an effect on the pressor response of the chemoreflex. Effects of muscimol (50 pmol/50 nl) on basal MAP and on the bradycardic response of the chemoreflex were prevented by prior microinjection of bicuculline (a GABAA antagonist, 40 pmol/50 nl) into the NTS. Bilateral microinjections of baclofen (12.5 and 25 pmol/50 nl) into the NTS produced an increase in baseline MAP [137 ± 9 vs. 108 ± 4 ( n= 7) and 145 ± 5 vs. 105 ± 2 mmHg ( n = 7), respectively], no changes in basal heart rate, and no effects on the bradycardic response; 25 pmol/50 nl only attenuated the pressor response to chemoreflex activation. The data show that activation of GABAA receptors in the NTS produces a significant reduction in the bradycardic response, whereas activation of GABAB receptors produces a significant reduction in the pressor response of the chemoreflex. We conclude that 1) GABAA but not GABAB plays an inhibitory role in neurons of the lateral commissural NTS involved in the parasympathetic component of the chemoreflex and 2) attenuation of the pressor response of the chemoreflex by activation of GABAB receptors may be due to inhibition of sympathoexcitatory neurons in the NTS or may be secondary to the large increase in baseline MAP produced by baclofen.
- Published
- 1999
9. c-Fos induction in the rostroventrolateral medulla by 5-HT3 receptor activation in the nucleus tractus solitarius
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Michel Hamon, Anne Nosjean, Raul Laguzzi, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)
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Male ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Biguanides ,MESH: Rats, Sprague-Dawley ,MESH: Microinjections ,c-Fos ,Rats, Sprague-Dawley ,0302 clinical medicine ,MESH: Animals ,Medulla Oblongata ,0303 health sciences ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,MESH: Proto-Oncogene Proteins c-fos ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Rostral ventrolateral medulla ,respiratory system ,16. Peace & justice ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,Medulla oblongata ,Proto-Oncogene Proteins c-fos ,circulatory and respiratory physiology ,Agonist ,medicine.medical_specialty ,Microinjections ,MESH: Rats ,medicine.drug_class ,Biology ,5-HT3 receptor ,03 medical and health sciences ,MESH: Analysis of Variance ,MESH: Medulla Oblongata ,Internal medicine ,Solitary Nucleus ,medicine ,Animals ,Microinjection ,Medulla ,030304 developmental biology ,Analysis of Variance ,Solitary nucleus ,MESH: Biguanides ,MESH: Male ,Rats ,Endocrinology ,nervous system ,biology.protein ,030217 neurology & neurosurgery - Abstract
International audience; The nucleus tractus solitarius (NTS) plays a crucial role in the reflex control of sympathetic tone through direct projections to the caudal and rostral regions of the ventrolateral medulla (CVLM and RVLM respectively). 5-HT3 receptor stimulation in the NTS increases both blood pressure and sympathetic tone. In order to investigate whether the ventrolateral medulla participates in these effects, the expression of c-Fos protein, a marker of neuronal activation, was examined at this level after intra-NTS microinjections of 1-(m-chlorophenyl)-biguanide, a selective 5-HT3 receptor agonist. A marked increase (93%) in the density of c-Fos-immunoreactive neurons was restricted to the most rostral part of the RVLM after this treatment. This effect could be prevented by prior intra-NTS microinjection of ondansetron, a selective 5-HT3 antagonist. These results suggest the participation of sympathoexcitatory neurons in the rostral RVLM in the pressor response to 5-HT3 receptor stimulation in the NTS.
- Published
- 1998
10. Role of serotonin3 receptors in the nucleus tractus solitarii on the carotid chemoreflex
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Benedito H. Machado, C. Sevoz, Raul Laguzzi, Michel Hamon, J. C. Callera, Université Pierre et Marie Curie - Paris 6 - UFR de Médecine Pierre et Marie Curie (UPMC), and Université Pierre et Marie Curie - Paris 6 (UPMC)
- Subjects
Atropine ,Male ,Sympathetic nervous system ,Sympathetic Nervous System ,Physiology ,[SDV]Life Sciences [q-bio] ,Biguanides ,Stimulation ,Kynurenic Acid ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Heart Rate ,Medicine ,Respiratory system ,Neurotransmitter ,Brain Mapping ,Carotid Body ,biology ,Respiration ,Vagus Nerve ,Ondansetron ,Chemoreceptor Cells ,Serotonin Receptor Agonists ,medicine.anatomical_structure ,Benzamides ,Serotonin Antagonists ,Cardiology and Cardiovascular Medicine ,circulatory and respiratory physiology ,Serotonin ,medicine.medical_specialty ,Microinjections ,5-HT3 receptor ,Physiology (medical) ,Internal medicine ,Reflex ,Solitary Nucleus ,Tidal Volume ,Animals ,Potassium Cyanide ,business.industry ,Bridged Bicyclo Compounds, Heterocyclic ,Rats ,Autonomic nervous system ,Endocrinology ,nervous system ,chemistry ,Receptors, Serotonin ,biology.protein ,Receptors, Serotonin, 5-HT3 ,business ,Nucleus - Abstract
The effects of serotonin3 (5-HT3)-receptor stimulation in the nucleus tractus solitarii (NTS) on the cardiovagal, sympathetic, and respiratory responses to activation of carotid body chemoreceptors were investigated in anesthetized rats. The chemoreflex responses were triggered by an intravenous administration of KCN (40 microg/kg) in spontaneously breathing urethan-chloralose-anesthetized rats or by an intracarotid administration of saline saturated with 100% CO2 in pancuronium bromide-paralyzed and artificially ventilated urethan-anesthetized rats. Microinjections of 5-HT (2.5-5 nmol) or the 5-HT3 agonist 1-(m-chlorophenyl)-biguanide (CPBG, 300-1,200 pmol) into the commissural NTS blocked in a dose-dependent manner the atropine-sensitive chemoreflex bradycardia elicited by KCN. However, neither 5-HT nor CPBG affected the KCN-induced increase in respiratory volume and the CO2-induced increases in blood pressure and lumbar sympathetic nerve discharge. The inhibitory effect of 5-HT or CPBG on KCN-induced bradycardia was blocked by prior intra-NTS microinjection of a 5-HT3 antagonist, such as zacopride (100 pmol) or ondansetron (100 pmol), or the A-type gamma-aminobutyric acid (GABA(A)) antagonist bicuculline (10 pmol). In contrast, local microinjections of antagonists acting at 5-HT1 and 5-HT2 receptors, such as methysergide (100 pmol) and ketanserin (10 pmol), respectively, did not prevent the actions of 5-HT or CPBG. These data show that the stimulation of 5-HT3 receptors in the NTS exerted an inhibitory influence, probably through the activation of a local GABAergic system, on the cardiovagal component of the chemoreflex. Because similar effects of 5-HT3-receptor stimulation in the NTS were previously found on the baroreflex and Bezold-Jarisch reflex responses, it can be inferred that NTS 5-HT3 receptors play a key modulatory role in the reflex control of the heart rate.
- Published
- 1997
11. Increased sympathetic nerve discharge without alteration in the sympathetic baroreflex response by serotonin3 receptor stimulation in the nucleus tractus solitarius of the rat
- Author
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Anne Nosjean, Bernard Franc, Raul Laguzzi, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,Sympathetic nervous system ,Sympathetic Nervous System ,Baroreceptor ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Blood Pressure ,MESH: Rats, Sprague-Dawley ,MESH: Microinjections ,MESH: Serotonin Antagonists ,Rats, Sprague-Dawley ,MESH: Pressoreceptors ,Zacopride ,chemistry.chemical_compound ,0302 clinical medicine ,MESH: Animals ,MESH: Sympathetic Nervous System ,0303 health sciences ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Blood Pressure ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,medicine.anatomical_structure ,Serotonin Antagonists ,circulatory and respiratory physiology ,Agonist ,Serotonin ,MESH: Receptors, Serotonin ,medicine.medical_specialty ,Microinjections ,MESH: Rats ,medicine.drug_class ,Pressoreceptors ,Baroreflex ,03 medical and health sciences ,Internal medicine ,Solitary Nucleus ,medicine ,Animals ,Microinjection ,030304 developmental biology ,Solitary nucleus ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,MESH: Male ,Rats ,Endocrinology ,nervous system ,chemistry ,Receptors, Serotonin ,MESH: Serotonin ,Neuroscience ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,030217 neurology & neurosurgery - Abstract
International audience; Previous studies have shown that serotonin3 receptor activation in the nucleus tractus solitarius (NTS) increased mean arterial pressure (MAP) and inhibited the cardiac component of the baroreceptor reflex [9]. We have examined the effects of such stimulation upon spontaneous and evoked sympathetic nerve activity. Microinjection of serotonin (10 nmol) into the NTS of halothane-anaesthetized, paralyzed and artificially ventilated rats produced an increase in MAP and lumbar sympathetic nerve discharge which could be completely prevented by prior local microinjection of zacopride, a potent serotonin3 antagonist (200 pmol). In addition, 1-(m-chlorophenyl)-biguanide, a selective serotonin3 receptor agonist, mimicked the sympathoexcitatory effect of serotonin. Since the gain of the sympathetic component of the baroreflex was unaltered after intra-NTS microinjection of serotonin, it could be concluded that serotonin3 receptors activation in the NTS induces a sympathetic activation which is not mediated through an inhibition of the sympathetic baroreceptor reflex arc.
- Published
- 1995
12. 5-HT2 receptors in the nucleus tractus solitarius: characterisation and role in cardiovascular regulation in the rat
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Nacera Merahi, Raul Laguzzi, and Hakan S. Orer
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Male ,Agonist ,Serotonin ,medicine.medical_specialty ,N-Methylaspartate ,Ketanserin ,Microinjections ,medicine.drug_class ,Blood Pressure ,Ritanserin ,Heart Rate ,Reference Values ,Internal medicine ,medicine ,Animals ,Receptor ,Molecular Biology ,Medulla Oblongata ,Ganglia, Sympathetic ,2,5-Dimethoxy-4-Methylamphetamine ,business.industry ,General Neuroscience ,Solitary nucleus ,Amphetamines ,Drug Synergism ,Rats, Inbred Strains ,Ganglionectomy ,Rats ,Blood pressure ,Endocrinology ,nervous system ,Receptors, Serotonin ,Reflex ,NMDA receptor ,Neurology (clinical) ,business ,circulatory and respiratory physiology ,Developmental Biology ,medicine.drug - Abstract
The effects of the local application of drugs acting on 5-HT2 receptors in the nucleus tractus solitarius (NTS) on the heart rate and blood pressure were investigated in normal and nodose ganglionectomized anaesthetized rats. The unilateral micro-injection of an agonist such as 2,5-dimethoxy-3-bromo-amphetamine (DOB) (0.1-0.5 pmol) or 2,5-dimethoxy-3-nitroamphetamine (DON) (0.1-0.5 pmol) produced a dose-dependent hypotension and bradycardia in both intact and ganglionectomized animals. These cardiovascular effects were similar to those observed after the unilateral micro-injection of low doses (pmol) of 5-HT, and could be prevented by the prior micro-injections of the 5-HT2 antagonists ketanserin, ritanserin and piremperone. These findings support the hypothesis that 5-HT2 receptors within the NTS play a role in the reflex regulation of blood pressure. In addition, it was also observed that the micro-injection of subthreshold doses of 5-HT or DOB significantly enhanced the hypotension and bradycardia produced by the unilateral micro-injection of N-methyl-D-aspartate (NMDA). The potentiation of NMDA depressor effects by 5-HT or DOB could be totally prevented by ketanserin or piremperone, suggesting that 5-HT acting upon 5-HT2 receptors in the NTS may intervene in the reflex control of blood pressure by modulating the glutamatergic transmission.
- Published
- 1992
13. Baroreceptor reflex inhibition induced by the stimulation of serotonin3 receptors in the nucleus tractus solitarius of the rat
- Author
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Raul Laguzzi, Hakan S. Orer, Nacera Merahi, A. M. Laporte, Henri Gozlan, and Michel Hamon
- Subjects
Male ,medicine.medical_specialty ,Baroreceptor ,Blood Pressure ,Pressoreceptors ,Baroreflex ,Bridged Bicyclo Compounds ,Internal medicine ,Reflex ,medicine ,Animals ,GABA-A Receptor Antagonists ,Serotonin Antagonists ,Phenylephrine ,Adrenergic alpha-Antagonists ,5-HT receptor ,Medulla Oblongata ,business.industry ,General Neuroscience ,Solitary nucleus ,Hemodynamics ,Rats, Inbred Strains ,Bridged Bicyclo Compounds, Heterocyclic ,Stimulation, Chemical ,Rats ,Endocrinology ,nervous system ,Receptors, Serotonin ,Benzamides ,Autoradiography ,Nodose Ganglion ,Serotonin ,business ,Phenylbiguanide ,medicine.drug - Abstract
Previous studies suggested that in the nucleus tractus solitarius, cardiovascular responses to serotonin may involve the simultaneous activation of more than one receptor subtype. In the present study, the cardiovascular effects of the local application of serotonin and different serotonin3 agonists and antagonists into the nucleus tractus solitarius were analysed in intact and unilaterally ganglionectomized rats. Unilateral injections of serotonin (5-15 nmol) produced a dose-dependent increase in blood pressure and partially antagonized the arterial baroreflex responses evoked by an i.v. injection of phenylephrine. Similar blood pressures response were obtained after unilateral microinjections of phenylbiguanide (5 nmol) and 2-methyl-serotonin (5 nmol), two serotonin3 receptor agonists. Bilateral microinjections of serotonin or phenylbiguanide produced more pronounced blood pressure effects and antagonized completely the baroreflex responses. Both blood pressure and baroreflex effects were antagonized by prior injections of specific serotonin3 antagonists such as zacopride (100 pmol) and ondansetron (100 pmol). Concomitant autoradiographic studies performed in intact and ganglionectomized rats, using [125I]iodozacopride, confirmed that serotonin3 receptors in the nucleus tractus solitarius are mainly located on vagal afferent fibers. In addition, serotonin microinjections made in the nucleus tractus solitarius ipsilateral to the ganglionectomy revealed a significant reduction in cardiovascular responses compared to intact animals. These results suggest that in the nucleus tractus solitarius of the rat, serotonin is involved in the reflex regulation of blood pressure through the stimulation of serotonin3 receptors presumably located on vagal afferent fibers. Since bicuculline antagonized the serotonin-mediated pressor responses, a serotonin3-dependent activation of an inhibitory GABAergic system within the nucleus tractus solitarius might be involved in blood pressure regulatory mechanisms.
- Published
- 1992
14. Inhibition of the bradycardic component of the von Bezold-Jarisch reflex and carotid chemoreceptor reflex by periaqueductal gray stimulation: involvement of medullary receptors
- Author
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Caroline Sévoz-Couche, Florence Netzer, Michel Hamon, Nathalie Mandjee, Anthony J.M. Verberne, Jean-François Bernard, and Raul Laguzzi
- Subjects
Male ,medicine.medical_specialty ,Sympathetic Nervous System ,Microinjections ,Biguanides ,Withdrawal reflex ,Tetrazoles ,Stimulation ,Bicuculline ,Periaqueductal gray ,Granisetron ,GABA Antagonists ,Rats, Sprague-Dawley ,Serotonin Agents ,Piperidines ,Parasympathetic Nervous System ,Internal medicine ,Reflex ,medicine ,Bradycardia ,Solitary Nucleus ,Animals ,Periaqueductal Gray ,Chemistry ,General Neuroscience ,Receptors, Neurokinin-1 ,Receptors, GABA-A ,Immunohistochemistry ,Chemoreceptor Cells ,Rats ,Endocrinology ,Carotid Arteries ,nervous system ,Bezold–Jarisch reflex ,Reflex bradycardia ,Receptors, Serotonin, 5-HT3 ,medicine.drug ,Phenylbiguanide - Abstract
Stimulation of the dorsolateral periaqueductal gray matter (dlPAG) and the B3 cell group inhibits the cardiovagal component of the baroreflex in rats. Our aim was to determine whether the defence reaction induces similar modulatory effects on the cardiac response of the von Bezold-Jarisch reflex and the carotid chemoreceptor reflex. We examined the effects of dlPAG stimulation on the reflex bradycardia triggered by systemic administration of phenylbiguanide or potassium cyanide. Electrical and chemical stimulation of the dlPAG produced marked inhibition of the cardiovagal components of the von Bezold-Jarisch and the carotid chemoreceptor reflexes. In addition, as 5-HT(3), NK(1) and GABA(A) receptor activation blocks cardiac reflex responses, we studied whether these receptors were involved in the dlPAG-induced inhibitory effects. We found that, after microinjection of granisetron (a 5-HT(3) receptor antagonist), bicuculline (a GABA(A) receptor antagonist) and GR-205171 (an NK(1) receptor antagonist) into the nucleus of the solitary tract (NTS), reflex bradycardic responses were preserved during dlPAG stimulation. Finally, activation of the B3 region also inhibited both reflex bradycardic responses, and these effects were prevented by prior blockade of 5-HT(3) receptors in the NTS. The inhibitory effect of dlPAG stimulation on the cardiac reflex responses was prevented by inhibition of neurons in the medullary B3 region. In conclusion, 5-HT(3), GABA(A) and NK(1) receptors in the NTS appear to be involved in the inhibition of the von Bezold-Jarisch reflex and the carotid chemoreceptor reflex bradycardia evoked by activation of neurons in the dlPAG and the raphe magnus.
- Published
- 2009
15. Inhibition of cardiac baroreflex by noxious thermal stimuli: a key role for lateral paragigantocellular serotonergic cells
- Author
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Michel Hamon, Raul Laguzzi, Remi Gau, Caroline Sévoz-Couche, and Jean-François Bernard
- Subjects
Male ,Serotonin ,Hot Temperature ,Microinjections ,Pain ,Serotonergic ,Granisetron ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Noxious stimulus ,Solitary Nucleus ,Premovement neuronal activity ,Animals ,GABA Agonists ,Fluorescent Dyes ,Nucleus raphe magnus ,Medulla Oblongata ,Chemistry ,Muscimol ,musculoskeletal, neural, and ocular physiology ,Genes, fos ,Heart ,Rostral ventrolateral medulla ,Baroreflex ,Immunohistochemistry ,Rats ,Anesthesiology and Pain Medicine ,Nociception ,nervous system ,Neurology ,cardiovascular system ,Raphe Nuclei ,Neurology (clinical) ,Serotonin Antagonists ,Raphe nuclei ,Neuroscience - Abstract
The present study was designed to identify the neuronal mechanisms causing cardiac baroreflex inhibition associated with thermal nociception in rats. Under urethane-anesthesia, noxious thermal stimulior = 48 degrees C were found to inhibit the cardiac baroreflex, whereas noxious stimulior = 46 degrees C had no effect. Using double immunohistochemical labeling, noxious stimulior = 48 degrees C were found to evoke primarily a strong expression of Fos protein (Fos) encoded by c-fos gene in serotonergic neurons of lateral paragigantocellular reticular nucleus (LPGi). Noxious stimulior = 46 degrees C did not evoke Fos expression in any serotonergic neurons of the brainstem. Local blockade of neuronal activity by bilateral microinjections of fluorescent muscimol (a GABA(A) receptor agonist tagged with a fluorophore that allowed visualization of the injections) into both the LPGi and the raphe magnus nucleus prevented the inhibitory effect of noxious stimulior = 48 degrees C on the cardiac baroreflex. Bilateral microinjections of granisetron (a 5-HT(3) antagonist) within the nucleus tractus solitarius also prevented the inhibition of cardiac baroreflex elicited by noxious stimulior = 48 degrees C. These results show that activation of serotonergic cells in the LPGi is critical to trigger nucleus tractus solitarius-mediated cardiac baroreflex inhibition elicited by intense thermal noxious stimuli.
- Published
- 2009
16. Critical role of B3 serotonergic cells in baroreflex inhibition during the defense reaction triggered by dorsal periaqueductal gray stimulation
- Author
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Michel Hamon, Jean-François Bernard, Caroline Sévoz-Couche, Remi Gau, Florence Netzer, and Raul Laguzzi
- Subjects
Male ,Serotonin ,Microinjections ,Blood Pressure ,Baroreflex ,Biology ,Serotonergic ,Periaqueductal gray ,Granisetron ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Heart Rate ,Neural Pathways ,Solitary Nucleus ,Premovement neuronal activity ,Animals ,Periaqueductal Gray ,GABA Agonists ,Homocysteine ,Defense Mechanisms ,Nucleus raphe magnus ,GABAA receptor ,Muscimol ,musculoskeletal, neural, and ocular physiology ,General Neuroscience ,Neural Inhibition ,Vagus Nerve ,Electric Stimulation ,Rats ,nervous system ,chemistry ,Serotonin Antagonists ,Neuroscience ,Proto-Oncogene Proteins c-fos - Abstract
The present study was designed to identify the serotonergic pathway causing baroreflex inhibition associated with the defense reaction in rats. Under conditions that produce physiological responses typical of the defense reaction, electrical stimulation of the dorsal periaqueductal gray (dPAG) was found to double c-Fos immunoreactive serotonergic neurons within the midrostrocaudal extent of the B3 group (which comprises the raphe magnus and the lateral paragigantocellular reticular nuclei) in anesthetized rats. Local blockade of neuronal activity by microinjection of muscimol (a GABAA receptor agonist) directly into the B3 region prevented the inhibitory effect of dPAG activation on the cardiac baroreflex. Conversely, neuron activation by local application of D,L-homocysteic acid into B3 region caused baroreflex inhibition that was suppressed by microinjection of granisetron (a 5-HT3 antagonist) into the nucleus tractus solitarius. These results show that activation of serotonergic cells in the mid-portion of B3 group is critical to trigger baroreflex inhibition occurring during the defense reaction evoked by dPAG stimulation. J. Comp. Neurol. 506:108 –121, 2008. © 2007 Wiley-Liss, Inc. Indexing terms: heart rate; serotonin; c-Fos; tractus solitarius; periaqueductal; ventromedial medulla
- Published
- 2007
17. Cardiac baroreflex facilitation evoked by hypothalamus and prefrontal cortex stimulation: role of the nucleus tractus solitarius 5-HT2A receptors
- Author
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Raul Laguzzi, Caroline Sévoz-Couche, Marie-Anne Comet, Michel Hamon, and Jean-François Bernard
- Subjects
Bradycardia ,Male ,endocrine system ,medicine.medical_specialty ,Baroreceptor ,Microinjections ,Physiology ,Prefrontal Cortex ,Stimulation ,Baroreflex ,Rats, Sprague-Dawley ,Piperidines ,Physiology (medical) ,Internal medicine ,Neural Pathways ,Solitary Nucleus ,Medicine ,Animals ,Receptor, Serotonin, 5-HT2A ,Atropine Derivatives ,Prefrontal cortex ,business.industry ,Brain ,Parasympatholytics ,Heart ,Neural Inhibition ,Preoptic Area ,Electric Stimulation ,Stimulation, Chemical ,Rats ,Fluorobenzenes ,Endocrinology ,medicine.anatomical_structure ,nervous system ,Atenolol ,Hypothalamus ,Sympatholytics ,Serotonin ,Ketanserin ,Serotonin Antagonists ,medicine.symptom ,business ,Nucleus ,Neuroscience ,circulatory and respiratory physiology - Abstract
We previously showed that serotonin (5-HT2) receptor activation in the nucleus of the tractus solitarius (NTS) produced hypotension, bradycardia, and facilitation of the baroreflex bradycardia. Activation of the preoptic area (POA) of the hypothalamus, which is involved in shock-evoked passive behaviors, induces similar modifications. In addition, previous studies showed that blockade of the infralimbic (IL) part of the medial prefrontal cortex, which sends projections to POA, produced an inhibitory influence on the baroreflex cardiac response. Thus, to assess the possible implication of NTS 5-HT2receptors in passive cardiovascular responses, we analyzed in anesthetized rats the effects of NTS inhibition and NTS 5-HT2receptor blockade on the cardiovascular modifications induced by chemical (0.3 M d,l-homocysteic acid) and electrical (50 Hz, 150–200 μA) stimulation of IL or POA. Intra-NTS microinjections of muscimol, a GABAAreceptor agonist, prevented the decreases in blood pressure and heart rate normally evoked by IL or POA activation. In addition, we found that intra-NTS microinjection of R(+)-α-(2,3-dimethoxyphenyl)-1-[2-(4-fluorophenylethyl)]-4-piperidine-methanol, a specific 5-HT2Areceptor antagonist, did not affect the decreases in cardiovascular baseline parameters induced by IL or POA stimulation but prevented the facilitation of the aortic baroreflex bradycardia normally observed during IL (+65 and +60%) or POA (+70 and +69%) electrical and chemical stimulation, respectively. These results show that NTS 5-HT2Areceptors play a key role in the enhancement of the cardiac response of the baroreflex but not in the changes in basal heart rate and blood pressure induced by IL or POA stimulation.
- Published
- 2006
18. 5-HT-mediated inhibition of cardiovagal baroreceptor reflex response during defense reaction in the rat
- Author
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Naïma Hanoun, Marie-Anne Comet, Caroline Sévoz-Couche, Raul Laguzzi, and Michel Hamon
- Subjects
Bradycardia ,Male ,medicine.medical_specialty ,Serotonin ,Baroreceptor ,Microinjections ,Physiology ,Stimulation ,Bicuculline ,Granisetron ,GABA Antagonists ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Phenylephrine ,Physiology (medical) ,Internal medicine ,medicine ,Solitary Nucleus ,Animals ,Neurotransmitter ,5-HT receptor ,Chemistry ,Solitary nucleus ,Fenclonine ,Vagus Nerve ,Baroreflex ,Receptors, GABA-A ,Electric Stimulation ,Rats ,Aggression ,Endocrinology ,nervous system ,cardiovascular system ,Reflex ,Serotonin Antagonists ,medicine.symptom ,Receptors, Serotonin, 5-HT3 ,Cardiology and Cardiovascular Medicine ,Adrenergic alpha-Agonists ,circulatory and respiratory physiology - Abstract
Previous studies showed that the cardiac response of the baroreceptor reflex (bradycardia) is inhibited during the defense reaction evoked by direct electrical or chemical stimulation of the periaqueductal gray (dPAG) in the rat. Whether central serotonin and nucleus tractus solitarius (NTS) serotonin3 (5-HT3) receptors might participate in this inhibition was investigated in urethane-anesthetized and atenolol-pretreated rats. Our results showed that both electrical and chemical stimulation of the dPAG produced a drastic reduction of the cardiovagal component of the baroreceptor reflex triggered by either intravenous administration of phenylephrine or aortic nerve stimulation. This inhibitory effect of dPAG stimulation on the baroreflex bradycardia was not observed in rats that had been pretreated with p-chlorophenylalanine (300 mg/kg ip daily for 3 days) to inhibit serotonin synthesis. Subsequent 5-hydroxytryptophan administration (60 mg/kg ip), which was used to restore serotonin synthesis, allowed the inhibitory effect of dPAG stimulation on both aortic and phenylephrine-induced cardiac reflex responses to be recovered in p-chlorophenylalanine-pretreated rats. On the other hand, in nonpretreated rats, the inhibitory effect of dPAG stimulation on the cardiac baroreflex response could be markedly reduced by prior intra-NTS microinjection of granisetron, a 5-HT3 receptor antagonist, or bicuculline, a GABAA receptor antagonist. These results show that serotonin plays a key role in the dPAG stimulation-induced inhibition of the cardiovagal baroreceptor reflex response. Moreover, they support the idea that 5-HT3 and GABAA receptors in the NTS contribute downstream to the inhibition of the baroreflex response caused by dPAG stimulation.
- Published
- 2004
19. Role of nucleus tractus solitarius 5-HT3 receptors in the defense reaction-induced inhibition of the aortic baroreflex in rats
- Author
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Caroline Sévoz-Couche, Marie-Anne Comet, Raul Laguzzi, and Michel Hamon
- Subjects
Male ,Nucleus tractus solitarius ,Physiology ,General Neuroscience ,Neural Inhibition ,Biology ,Baroreflex ,Granisetron ,Rats ,Rats, Sprague-Dawley ,nervous system ,Escape Reaction ,Solitary Nucleus ,Animals ,Serotonin 5-HT3 Receptor Antagonists ,Receptors, Serotonin, 5-HT3 ,Receptor ,Neuroscience ,Aorta ,circulatory and respiratory physiology - Abstract
Different stressful conditions elicit a typical behavior called the defense reaction. Our aim was to determine whether 5-HT3 receptors in the nucleus tractus solitarius (NTS) are involved in 1) the inhibition of the baroreflex bradycardia and 2) the rise in blood pressure, which are known to occur during the defense reaction. In urethane-anesthetized rats, the defense reaction was elicited by electrical stimulation of the dorsomedial nucleus of the hypothalamus (DMH) or the dorsal part of the periaqueductal gray (dPAG). Direct electrical stimulation of the aortic depressor nerve was used to trigger the typical baroreflex responses. Aortic stimulation at high (100–150 μA) and low (50–90 μA) intensity produced a decrease in heart rate of –39 to –44% (relative to baseline, Group 1 responses, n = 113) and –19 to –24% ( Group 2 responses, n = 43), respectively. In spontaneously breathing rats, Group 1 and Group 2 bradycardiac responses were inhibited during DMH (–75 ± 4% and –96 ± 4%, n = 38 and n = 11, respectively), as well as dPAG (–81 ± 3% and –95 ± 4%, n = 36 and n = 10, respectively) stimulation. The aortic baroreflex bradycardia was hardly affected by DMH or dPAG stimulation when bicuculline (5 pmol), a specific GABAA receptor antagonist, had previously been microinjected into the NTS. Likewise, NTS microinjections of granisetron, a specific 5-HT3 receptor antagonist, prevented, in a dose-dependent manner, the baroreflex bradycardia inhibition. In addition, intra-NTS granisetron did not affect the rise in blood pressure induced by either site stimulation. These data show that 5-HT3 receptors in the NTS are involved in the GABAergic inhibition of the aortic baroreflex bradycardia, but not in the rise in blood pressure, occurring during the defense reaction elicited by DMH or dPAG stimulation.
- Published
- 2003
20. Involvement of NMDA receptors in the pressor response to microinjection of 5-HT3 agonist into the NTS of awake rats
- Author
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Ricardo Vieira Reges, Anne Nosjean, Raul Laguzzi, Benedito H. Machado, Leni G.H. Bonagamba, Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Male ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Blood Pressure ,Sodium Chloride ,MESH: Microinjections ,0302 clinical medicine ,MESH: Animals ,Receptor ,0303 health sciences ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Chemistry ,Tribromoethanol ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Blood Pressure ,MESH: Excitatory Amino Acid Antagonists ,MESH: Glutamic Acid ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,NMDA receptor ,circulatory and respiratory physiology ,Agonist ,Serotonin ,medicine.medical_specialty ,Mean arterial pressure ,MESH: Sodium Chloride ,Microinjections ,MESH: Rats ,medicine.drug_class ,Glutamic Acid ,Receptors, N-Methyl-D-Aspartate ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Internal medicine ,Solitary Nucleus ,medicine ,Animals ,Rats, Wistar ,Microinjection ,5-HT receptor ,030304 developmental biology ,MESH: Receptors, N-Methyl-D-Aspartate ,Endocrine and Autonomic Systems ,MESH: Rats, Wistar ,MESH: Male ,Rats ,Endocrinology ,2-Amino-5-phosphonovalerate ,nervous system ,MESH: 2-Amino-5-phosphonovalerate ,MESH: Serotonin ,Neurology (clinical) ,Excitatory Amino Acid Antagonists ,030217 neurology & neurosurgery - Abstract
International audience; Previous studies have shown that the activation of 5-HT3 receptors in the nucleus tractus solitarii (NTS) increases the baseline mean arterial pressure (MAP). In the present study, we evaluated the possible involvement of NMDA receptors in this pressor response. Four days before the experiments, under tribromoethanol anesthesia, rats received two guide cannulas in the direction of the NTS, and 1 day before the experiments, under tribromoethanol anesthesia, the femoral artery was cannulated for pulsatile arterial pressure (PAP), MAP, and heart rate (HR) measurements. On the day of the experiments, 2-methyl-serotonin, a 5-HT3 agonist, was microinjected into the NTS after microinjection of saline or AP-5, a selective NMDA receptor antagonist. Microinjection of 2-methyl-serotonin (5 nmol/50 nl) into the NTS after the vehicle (saline) produced a significant increase in MAP (+ 20 +/- 5 mm Hg, n = 8) while microinjection of 2-methyl-serotonin after microinjection of AP-5 (10 nmol/50 nl) produced no change in baseline MAP (-1 +/- 3 mm Hg, n = 11). Microinjection of AP-5 into the NTS produced no significant changes in the baseline MAP and HR. The data show that the increase in MAP in response to microinjection of a 5-HT3 agonist into the NTS is dependent on NMDA receptors.
- Published
- 2002
21. Stimulation of 5-HT2 receptors in the nucleus tractus solitarius enhances NMDA receptor-mediated reflex-evoked bradycardiac responses in the rat
- Author
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Raul Laguzzi, Awa N'Diaye, Anne Nosjean, Michel Hamon, Caroline Sévoz-Couche, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,MESH: Phenylephrine ,Ketanserin ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Stimulation ,Blood Pressure ,MESH: Rats, Sprague-Dawley ,MESH: Microinjections ,MESH: Serotonin Antagonists ,MESH: Dose-Response Relationship, Drug ,Rats, Sprague-Dawley ,MESH: Pressoreceptors ,Phenylephrine ,0302 clinical medicine ,Heart Rate ,Anesthesia ,MESH: Animals ,Sympathomimetics ,MESH: Heart Rate ,MESH: Amphetamines ,0303 health sciences ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Chemistry ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Ketanserin ,MESH: Blood Pressure ,MESH: Excitatory Amino Acid Antagonists ,Receptor antagonist ,Chemoreceptor Cells ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,Serotonin Antagonists ,medicine.drug ,Agonist ,medicine.medical_specialty ,Serotonin ,MESH: Receptors, Serotonin ,MESH: Chemoreceptor Cells ,Microinjections ,MESH: Rats ,medicine.drug_class ,MESH: Reflex ,Pressoreceptors ,MESH: Anesthesia ,Receptors, N-Methyl-D-Aspartate ,MESH: Bradycardia ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,Internal medicine ,Reflex ,medicine ,Bradycardia ,Solitary Nucleus ,Animals ,5-HT receptor ,030304 developmental biology ,MESH: Receptors, N-Methyl-D-Aspartate ,Dose-Response Relationship, Drug ,Endocrine and Autonomic Systems ,Solitary nucleus ,Amphetamines ,MESH: Sympathomimetics ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,MESH: Male ,Rats ,Endocrinology ,2-Amino-5-phosphonovalerate ,nervous system ,Receptors, Serotonin ,Reflex bradycardia ,MESH: 2-Amino-5-phosphonovalerate ,MESH: Serotonin ,Neurology (clinical) ,Excitatory Amino Acid Antagonists ,030217 neurology & neurosurgery ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences - Abstract
International audience; The modulation by 5-HT2 receptors in the nucleus tractus solitarius of the reflex bradycardia evoked by stimulation of peripheral baroreceptors and cardiopulmonary chemoreceptors, and their possible functional interactions with local NMDA receptors, were investigated in pentobarbital- and urethane-anaesthetized rats, respectively. Microinjection of the 5-HT2 receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (0.1-0.5 pmol), into the nucleus tractus solitarius elicited a dose-dependent hypotension and bradycardia. Bilateral microinjections at the same site of a subthreshold dose of 2,5-dimethoxy-4-iodoamphetamine (0.05 pmol) significantly enhanced the aforementioned reflex-evoked bradycardiac responses. In contrast, local bilateral microinjections of the NMDA receptor antagonist, 2-amino-5-phosphonopentanoic acid (500 and 1000 pmol), reduced, in a dose-dependent manner, both reflex-evoked responses. The facilitatory effect of 2,5-dimethoxy-4-iodoamphetamine upon these reflex-evoked bradycardiac responses was prevented by prior local microinjection of low doses of either the selective 5-HT2 receptor antagonist, ketanserin (10 pmol), or 2-amino-5-phosphonopentanoic acid (100 pmol), which, on their own, did not affect the reflex-associated bradycardia. These data suggest that 5-HT2 receptors within the nucleus tractus solitarius participate in a facilitatory modulation of the reflex control of heart rate, probably through functional interactions with local NMDA receptors.
- Published
- 2001
22. Microinjection of a 5-HT3 receptor agonist into the NTS of awake rats inhibits the bradycardic response to activation of the von Bezold-Jarisch reflex
- Author
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Raul Laguzzi, Leni G.H. Bonagamba, Anne Nosjean, Daniel M Leal, João Carlos Callera, Benedito H. Machado, Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,Sympathetic Nervous System ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Blood Pressure ,030204 cardiovascular system & hematology ,MESH: Microinjections ,Synaptic Transmission ,0302 clinical medicine ,Nerve Fibers ,Heart Rate ,MESH: Animals ,MESH: Sympathetic Nervous System ,MESH: Heart Rate ,MESH: Solitary Nucleus ,biology ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Chemistry ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Neural Inhibition ,MESH: Blood Pressure ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,MESH: Reflex, Abnormal ,Arousal ,Agonist ,Mean arterial pressure ,medicine.medical_specialty ,Serotonin ,MESH: Receptors, Serotonin ,Microinjections ,MESH: Rats ,medicine.drug_class ,MESH: Receptors, Serotonin, 5-HT3 ,5-HT3 receptor ,MESH: Bradycardia ,03 medical and health sciences ,Parasympathetic Nervous System ,Internal medicine ,MESH: Analysis of Variance ,medicine ,Bradycardia ,Solitary Nucleus ,MESH: Synaptic Transmission ,Animals ,Rats, Wistar ,Microinjection ,MESH: Nerve Fibers ,Analysis of Variance ,Reflex, Abnormal ,Solitary nucleus ,MESH: Arousal ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Neural Inhibition ,MESH: Rats, Wistar ,MESH: Male ,Rats ,Endocrinology ,Bezold–Jarisch reflex ,nervous system ,Receptors, Serotonin ,biology.protein ,Reflex ,MESH: Parasympathetic Nervous System ,MESH: Serotonin ,Receptors, Serotonin, 5-HT3 ,030217 neurology & neurosurgery ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences - Abstract
International audience; In the present study we investigated the effects of bilateral microinjection into the lateral commissural nucleus tractus solitarius (NTS) of 2-methyl-5-HT, a 5-HT3 receptor agonist, on the bradycardic response of the von Bezold-Jarisch reflex of awake rats. We evaluated mainly the bradycardic response because in previous studies we documented that the hypotensive response of the von-Bezold-Jarisch reflex in awake rats is secondary to the intense bradycardic response. The Bezold-Jarisch reflex was activated by intravenous injection of serotonin (8 microg/kg) in awake rats before and 1, 3, 10, 20 and 60 min after bilateral microinjection of 2-methyl-5-HT (5 nmol/50 nl, n = 8) into the NTS. Microinjections of 2-methyl-5-HT into the NTS produced a significant increase in basal mean arterial pressure [(MAP), 97 +/- 4 vs. 114 +/- 4 mmHg), no changes in basal heart rate and a significant reduction in bradycardic (-78 +/- 19; -94 +/- 24 and -107 +/- 21 bpm) and hypotensive (-16 +/- 4; -10 +/- 5 and -17 +/- 4 mmHg) responses to activation of the von Bezold-Jarisch reflex at 3, 10 and 20 min, respectively, when compared with the control value (-231 +/- 13 bpm and -43 +/- 4 mmHg). The data of the present study suggest that serotonin acting on 5-HT3 receptors in the NTS may play an important inhibitory neuromodulatory role in the bradycardic response to activation of the von Bezold-Jarisch reflex.
- Published
- 2001
23. •Bradycardic responses to microinjection of N-methyl-D-aspartate into the nucleus tractus solitarius are inhibited by local activation of 5-HT(3) receptors
- Author
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L.G.H Bonagamba, Michel Hamon, Caroline Sévoz-Couche, João Carlos Callera, Benedito H. Machado, A N'Diaye, Raul Laguzzi, K Uygun-Louvet, Université Pierre et Marie Curie - Paris 6 - UFR de Médecine Pierre et Marie Curie (UPMC), and Université Pierre et Marie Curie - Paris 6 (UPMC)
- Subjects
Agonist ,Male ,medicine.medical_specialty ,Kainic acid ,N-Methylaspartate ,Sympathetic Nervous System ,Microinjections ,medicine.drug_class ,[SDV]Life Sciences [q-bio] ,Biguanides ,Kainate receptor ,AMPA receptor ,Biology ,Bicuculline ,Granisetron ,GABA Antagonists ,Rats, Sprague-Dawley ,Cellular and Molecular Neuroscience ,chemistry.chemical_compound ,Receptors, Kainic Acid ,Heart Rate ,Internal medicine ,medicine ,Excitatory Amino Acid Agonists ,Solitary Nucleus ,Animals ,Microinjection ,alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid ,Pharmacology ,Hemodynamics ,respiratory system ,Baroreflex ,Receptor antagonist ,Rats ,Serotonin Receptor Agonists ,Endocrinology ,nervous system ,chemistry ,Receptors, Serotonin ,NMDA receptor ,Serotonin Antagonists ,Receptors, Serotonin, 5-HT3 ,circulatory and respiratory physiology ,Ionotropic effect - Abstract
Previous reports have described that glutamate ionotropic receptors in the nucleus tractus solitarius (NTS) are involved in the reflex control of heart rate, and that such a control can be inhibited by NTS-5-HT(3) receptor stimulation. In the present study, we examined in urethane anaesthetized rats the effects of intra-NTS microinjection of 1-(m-chlorophenyl)-biguanide (CPBG), a potent and selective 5-HT(3) receptor agonist, on the cardiovascular responses to local administration of glutamate ionotropic receptor agonists. Intra-NTS microinjection of CPBG reduced the atropine-sensitive bradycardia elicited by local microinjection of NMDA without affecting the cardiovascular responses to intra-NTS microinjections of AMPA or kainic acid. The reduction by CPBG of the NMDA-evoked cardiac response was blocked by prior intra-NTS microinjection of granisetron, a 5-HT(3) receptor antagonist, as well as bicuculline, a GABA(A) receptor antagonist. These results suggest that the stimulation of NTS 5-HT(3) receptors specifically reduces, via a GABA-dependent mechanism, the cardiac response to local NMDA administration.
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- 2000
24. Activation of GABA receptors in the NTS of awake rats reduces the gain of baroreflex bradycardia
- Author
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Anne Nosjean, Raul Laguzzi, João Carlos Callera, Benedito H. Machado, Leni G.H. Bonagamba, Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP, Brazil, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,Baclofen ,MESH: Phenylephrine ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Blood Pressure ,030204 cardiovascular system & hematology ,Phenylephrine ,chemistry.chemical_compound ,0302 clinical medicine ,Heart Rate ,MESH: Baroreflex ,MESH: Animals ,MESH: Heart Rate ,MESH: Receptors, GABA-B ,MESH: Receptors, GABA-A ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Muscimol ,GABAA receptor ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Blood Pressure ,MESH: Baclofen ,medicine.drug ,Nitroprusside ,Mean arterial pressure ,medicine.medical_specialty ,Cardiotonic Agents ,MESH: Rats ,Baroreflex ,MESH: Bradycardia ,03 medical and health sciences ,Cellular and Molecular Neuroscience ,MESH: GABA Agonists ,Internal medicine ,Bradycardia ,Solitary Nucleus ,medicine ,Animals ,Rats, Wistar ,GABA Agonists ,Microinjection ,Antihypertensive Agents ,MESH: Antihypertensive Agents ,Endocrine and Autonomic Systems ,Solitary nucleus ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,MESH: Rats, Wistar ,MESH: Cardiotonic Agents ,Receptors, GABA-A ,Atenolol ,MESH: Nitroprusside ,MESH: Male ,Rats ,Endocrinology ,Receptors, GABA-B ,chemistry ,nervous system ,Neurology (clinical) ,030217 neurology & neurosurgery ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Muscimol - Abstract
International audience; In the present study we evaluated the effects of bilateral microinjection of muscimol (a GABA(A) receptor agonist) and baclofen (a GABA(B) receptor agonist) into the lateral commissural nucleus tractus solitarii (NTS) of awake rats on the gain of the baroreflex (BG) activated by a short duration (10-15 s) infusion of phenylephrine (Phe, 2.5 microg/0.05 ml, i.v.). Microinjection of muscimol (50 pmol/50 nl, n=8) into the NTS produced a significant increase in baseline mean arterial pressure ((MAP) 122+/-6 vs. 101+/-2 mmHg), no changes in baseline heart rate (HR) and a reduction in BG (-1.59+/-0. 1 vs. -0.69+/-0.1 beats/mmHg). Microinjection of baclofen (6.25 pmol/50 nl, n=6) into the NTS also produced a significant increase in baseline MAP (138+/-5 vs. 103+/-2 mmHg), no changes in baseline HR and a reduction in BG (-1.54+/-0.3 vs. -0.53+/-0.2 beats/mmHg). Considering that the reduction in BG could be secondary to the increase in MAP in response to microinjection of muscimol (n=6) or baclofen (n=7) into the NTS, in these two groups of rats we brought the MAP back to baseline by infusion of sodium nitroprusside (NP, 3.0 microg/0.05 ml, i.v.). Under these conditions, we verified that the BG remained significantly reduced after muscimol (-1.49+/-0.2 vs. -0.35+/-0.2 beats/mmHg) and after baclofen (-1.72+/-0.2 vs. -0.33+/-0.2 beats/mmHg) when compared to control. Reflex tachycardia was observed during the normalization of MAP by NP infusion and, in order to prevent the autonomic imbalance from affecting BG, we used another group of rats treated with atenolol (5 mg/kg, i.v.), a beta1 receptor antagonist. In rats previously treated with atenolol and submitted to NP infusion, we verified that BG remained reduced after microinjection of muscimol or baclofen into the NTS. The data show that activation of GABA(A) and GABA(B) receptors, independently of the changes in the baseline MAP or HR, inhibited the neurons of the NTS involved in the parasympathetic component of the baroreflex.
- Published
- 2000
25. Dorsal medullary 5-HT 3 receptors and sympathetic premotor neurones in the rat
- Author
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Caroline Sévoz-Couche, Anne Nosjean, Bernard Franc, Michel Hamon, Raul Laguzzi, Université Pierre et Marie Curie - Paris 6 - UFR de Médecine Pierre et Marie Curie (UPMC), Université Pierre et Marie Curie - Paris 6 (UPMC), Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,MESH: Phenylephrine ,Sympathetic Nervous System ,Baroreceptor ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV]Life Sciences [q-bio] ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Biguanides ,MESH: Aorta, Abdominal ,Action Potentials ,Blood Pressure ,Stimulation ,MESH: Rats, Sprague-Dawley ,MESH: Microinjections ,MESH: Carbon Dioxide ,Cardiovascular System ,Rats, Sprague-Dawley ,Phenylephrine ,chemistry.chemical_compound ,0302 clinical medicine ,MESH: Baroreflex ,MESH: Animals ,Aorta, Abdominal ,Glutamate receptor antagonist ,MESH: Sympathetic Nervous System ,Lung ,MESH: Action Potentials ,Motor Neurons ,Carotid Body ,0303 health sciences ,education.field_of_study ,MESH: Electrophysiology ,MESH: Solitary Nucleus ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Chemistry ,Respiration ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Rostral ventrolateral medulla ,MESH: Blood Pressure ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,Electrophysiology ,Medulla oblongata ,MESH: Motor Neurons ,circulatory and respiratory physiology ,MESH: Carotid Body ,medicine.medical_specialty ,MESH: Receptors, Serotonin ,Cardiotonic Agents ,Microinjections ,MESH: Rats ,MESH: Receptors, Serotonin, 5-HT3 ,Population ,Baroreflex ,03 medical and health sciences ,Internal medicine ,Solitary Nucleus ,medicine ,Animals ,MESH: Lung ,education ,Ligation ,030304 developmental biology ,MESH: Respiration ,MESH: Cardiovascular System ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Original Articles ,MESH: Cardiotonic Agents ,Carbon Dioxide ,MESH: Ligation ,MESH: Male ,MESH: Biguanides ,Rats ,Endocrinology ,nervous system ,Receptors, Serotonin ,Reflex ,Receptors, Serotonin, 5-HT3 ,Neuroscience ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,030217 neurology & neurosurgery - Abstract
Our aim was to determine whether the cardiovascular neurones in the rostro-ventrolateral medulla (CV-RVLM neurones) were involved in the sympathoexcitation induced by stimulation of 5-HT3 receptors in the region of the nucleus tractus solitarii (NTS). Experiments were performed in pentobarbitone-anaesthetized rats, artificially ventilated and paralysed with pancuronium bromide. Using extracellular recordings, different types of RVLM neurones were characterized: cardiovascular (CV), ventilation-related and baroreflex-insensitive (unidentified) neurones. The CV-RVLM cells were further subdivided into three populations according to their axonal conduction velocities: A (1.2 ± 0.1 m s−1), B (2.5 ± 0.2 m s−1) and C (6.8 ± 1.1 m s−1). Only the CV-RVLM neurones of the A and B categories were partially inhibited (−30 %) by a hypotensive dose (2.5 μg kg−1 i.v.) of clonidine. Microinjections into the region of the commissural NTS of 1-(m-chlorophenyl)-biguanide (CPBG, 2 nmol), a selective 5-HT3 receptor agonist, elicited an increase in both lumbar sympathetic nerve discharge (SND) and arterial pressure. In addition, this treatment produced a marked excitation of CV-RVLM neurones of the A and B categories, without affecting those of the C type, as well as ventilation-related and unidentified RVLM cells. The activity of the CV neurones in the caudo-ventrolateral part of the medulla oblongata (CV-CVLM) was not modified by 5-HT3 receptor stimulation in the NTS. Prior intra-NTS microinjections of ondansetron (300 pmol, a selective 5-HT3 receptor antagonist) into the region of the commissural NTS prevented the excitation of A and B CV-RVLM neurones induced by CPBG. Intracarotid administration of saline saturated with CO2 (chemoreceptor activation) elicited both an increase in the SND and an excitation of the clonidine-insensitive CV-RVLM neurones of the C type, without affecting A and B neurones. In conclusion, the sympathoexcitation elicited following 5-HT3 receptor stimulation in the region of the commissural NTS of pentobarbitone-anaesthetized rats seems to result from the excitation of two different pools of clonidine-sensitive CV-RVLM neurones. These neurones are apparently not involved in the sympathetic component of the chemoreceptor reflex. The rostro-ventrolateral medulla (RVLM) and nucleus tractus solitarii (NTS) are critically involved in the reflex control of sympathetic activity (Guyenet, Filtz & Donaldson, 1987; Sun & Guyenet, 1987; Spyer, 1994). The RVLM contains neurones that receive a number of inputs both peripheral and central in origin that influence sympathetic nerve activity (Sun & Guyenet, 1987; Spyer, 1994). Previous reports have described two populations of cardiovascular (CV)-RVLM neurones that project to the thoracic spinal cord (Brown & Guyenet, 1985; Sun & Guyenet, 1985). The first population consists of clonidine-sensitive cells with slow-conducting axons. The second population corresponds to cells that do not respond to hypotensive doses of clonidine, and are characterized by a much higher conduction velocity (Sun & Guyenet, 1986). The NTS is the site of termination of afferent fibres arising from arterial baroreceptors (baroreflex), cardiopulmonary chemoreceptors (Bezold-Jarisch reflex) and carotid chemoreceptors (chemoreflex) (Palkovits & Zaborsky, 1977; Kalia & Mesulam, 1980; Jordan & Spyer, 1986). For baro- and Bezold-Jarisch reflexes, which seem to share the same integrating mechanisms and pathways in the brain (Verberne & Guyenet, 1992), second-order neurones project from the NTS to the caudal ventrolateral part of the medulla (CVLM) (Gordon 1987; Guyenet et al. 1987; Verberne & Guyenet, 1992). These neurones exert an excitatory action on the GABAergic CVLM neurones that project to the RVLM where they inhibit the CV-RVLM neurones of this pressor area (Brown & Guyenet, 1985; Sun & Guyenet, 1985; Jeske, Reis & Milner, 1995). Some of the CV-RVLM neurones additionally constitute an efferent link in the sympathetic component of the chemoreflex (Guyenet & Brown, 1986; Sun & Reis, 1995). Indeed, it has been demonstrated that some NTS chemosensitive neurones have axonal projections to the RVLM (Koshiya & Guyenet, 1996). Within the NTS, serotonin (5-hydroxytryptamine, 5-HT) seems to be involved in the reflex control of blood pressure. Studies in both anaesthetized and conscious rats have shown that 5-HT2 receptor stimulation in the NTS elicits the typical CV responses of baroreceptor activation (Merahi, Orer & Laguzzi, 1992a; Callera, Bonagamba, Sevoz, Laguzzi & Machado, 1997a). On the other hand, stimulation of NTS 5-HT3 receptors elicits a chemoreceptor-like increase in arterial pressure and lumbar sympathetic activity (Merahi, Orer, Laporte, Gozlan, Hamon & Laguzzi, 1992b; Callera, Sevoz, Laguzzi & Machado, 1997b). In experiments aimed at analysing the mechanism (s) responsible for this sympatho-excitatory effect, we observed that stimulation of 5-HT3 receptors in the NTS did not inhibit the sympathetic component of the baroreflex (Nosjean, Franc & Laguzzi, 1995). Accordingly, it can be inferred that 5-HT3 receptor-mediated sympathoexcitation is not the consequence of the disruption of tonic baroreceptor sympathoinhibitory messages. However, our finding is compatible with the idea that CV-RVLM neurones may be involved in the sympathoexcitatory effect of 5-HT3 receptor stimulation in the NTS. In other experiments, we also observed that prior microinjections of pressor (nanomolar) doses of 5-HT3 receptor agonists into the NTS did not increase the sympathetic chemoreflex response (Sevoz, Callera, Machado, Hamon & Laguzzi, 1997). However, this observation does not rule out the possibility that under some physiological conditions, 5-HT released in the NTS may excite the NTS-RVLM sympathetic chemoreflex pathway (Koshiya & Guyenet, 1996), and the CV-RVLM neurones involved in this reflex. Indeed, as previously observed with the pressor chemoreflex response (Sun & Reis, 1995), we recently found that the microinjection of kynurenic acid, a glutamate receptor antagonist, into the RVLM blocked the pressor effects elicited by 5-HT3 receptor stimulation in this area (Sevoz, Hamon & Laguzzi, 1996b). In order to elucidate the possible role of CV-RVLM neurones in the sympathetic response to 5-HT3 receptor stimulation in the NTS, we have analysed the effects of intra-NTS microinjections of a potent and selective 5-HT3 receptor agonist, 1-(m-chlorophenyl)-biguanide (CPBG), as well as the effects of chemoreflex activation, on the activity of the different categories of RVLM neurones. In addition, the possible effects of intra-NTS administration of CPBG on the CV-CVLM neurones were also investigated.
- Published
- 1998
26. Microinjection of a serotonin3 receptor agonist into the NTS of unanesthetized rats inhibits the bradycardia evoked by activation of the baro- and chemoreflexes
- Author
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João Carlos Callera, Benedito H. Machado, C. Sevoz, Raul Laguzzi, Université Pierre et Marie Curie - Paris 6 - UFR de Médecine Pierre et Marie Curie (UPMC), and Université Pierre et Marie Curie - Paris 6 (UPMC)
- Subjects
Male ,Agonist ,Bradycardia ,Serotonin ,Mean arterial pressure ,medicine.medical_specialty ,Microinjections ,Physiology ,medicine.drug_class ,[SDV]Life Sciences [q-bio] ,Blood Pressure ,Pressoreceptors ,Baroreflex ,Heart Rate ,Internal medicine ,medicine ,Animals ,Rats, Wistar ,Phenylephrine ,Microinjection ,Chemistry ,General Neuroscience ,Solitary nucleus ,Chemoreceptor Cells ,Rats ,Serotonin Receptor Agonists ,Endocrinology ,nervous system ,Reflex bradycardia ,cardiovascular system ,Neurology (clinical) ,medicine.symptom ,human activities ,circulatory and respiratory physiology ,medicine.drug - Abstract
In the present study we investigated the effects of microinjection into the commissural nucleus tractus solitarius (NTS) of unanesthetized rats of 2-methylserotonin (2-methyl-5-HT), a 5-HT3 receptor agonist, on the cardiac component of the baro- and chemoreflexes. The study was performed in conscious freely moving rats in order to avoid the possible effects of anesthetics on the cardiovascular responses to microinjection of neuroactive substances into the NTS. The baroreflex (phenylephrine, 0.5-2.0 micrograms/kg, i.v.) and the chemoreflex (potassium cyanide, 40 micrograms/rat, i.v) were activated in different groups of rats before and after bilateral microinjection of 2-methyl-5-HT into the NTS. Microinjections of 2-methyl-5-HT (5 nmol/50 nl) into the NTS produced a significant increase in basal mean arterial pressure (101 +/- 3 versus 125 +/- 8 mmHg), no changes in basal HR and a significant reduction in the reflex bradycardia triggered by baroreflex activation at 3 (-28 +/- 7 bpm), 10 (-35 +/- 4 bpm) and 20 min (-34 +/- 5 bpm) in comparison with the control value (-68 +/- 9 bpm). A similar reduction in the bradycardic response to chemoreflex activation was observed at 3 (-94 +/- 35 bpm), 10 (-98 +/- 38 bpm) and 20 min (-110 +/- 29 bpm) after 2-methyl-5-HT in comparison with the control value (-178 +/- 19 bpm). The effect of 2-methyl-5-HT on the basal mean arterial pressure and on the bradycardia evoked by stimulation of the baro- and chemoreflexes was blocked by pretreatment with granisetron bilaterally microinjected (500 pmol/50 nl) into the NTS. The data show that the stimulation of 5-HT3 receptors in the NTS of unanesthetized rats elicits a significant increase in basal mean arterial pressure and decreases the bradycardic response to baro- or chemoreflex activation.
- Published
- 1997
27. Stimulation of 5-HT3 receptors in the NTS inhibits the cardiac Bezold-Jarisch reflex response
- Author
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C. Sevoz, Anne Nosjean, Raul Laguzzi, Michel Hamon, J. C. Callera, Benedito H. Machado, Université Pierre et Marie Curie - Paris 6 - UFR de Médecine Pierre et Marie Curie (UPMC), Université Pierre et Marie Curie - Paris 6 (UPMC), Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Male ,Sympathetic Nervous System ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV]Life Sciences [q-bio] ,Biguanides ,Blood Pressure ,Stimulation ,MESH: Rats, Sprague-Dawley ,Pharmacology ,MESH: Microinjections ,MESH: GABA Antagonists ,MESH: Serotonin Antagonists ,GABA Antagonists ,Rats, Sprague-Dawley ,MESH: Heart Conduction System ,MESH: Pressoreceptors ,0302 clinical medicine ,MESH: Vagus Nerve ,Medicine ,MESH: Animals ,MESH: Sympathetic Nervous System ,0303 health sciences ,MESH: Solitary Nucleus ,biology ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Heart ,Vagus Nerve ,MESH: Neural Inhibition ,MESH: Blood Pressure ,MESH: Serotonin Receptor Agonists ,Serotonin Receptor Agonists ,medicine.anatomical_structure ,Anesthesia ,Serotonin Antagonists ,Cardiology and Cardiovascular Medicine ,Serotonin ,MESH: Receptors, Serotonin ,Microinjections ,MESH: Rats ,MESH: Reflex ,Central nervous system ,Pressoreceptors ,5-HT3 receptor ,03 medical and health sciences ,Heart Conduction System ,Physiology (medical) ,Reflex ,Solitary Nucleus ,Animals ,030304 developmental biology ,business.industry ,Solitary nucleus ,Neural Inhibition ,MESH: Biguanides ,MESH: Male ,Rats ,Vagus nerve ,MESH: Heart ,Bezold–Jarisch reflex ,nervous system ,Receptors, Serotonin ,Reflex bradycardia ,biology.protein ,MESH: Serotonin ,business ,030217 neurology & neurosurgery ,Phenylbiguanide - Abstract
International audience; Intra-atrial administration of phenylbiguanide has been shown to trigger, through the stimulation of vagal afferent C-fibers, reflex bradycardia, hypotension, and sympathoinhibition classically known as the Bezold-Jarisch (B-J) reflex (O. Krayer. Naunyn-Schmiedeberg's Arch. Exp. Pathol. Pharmacol. 240: 361-368, 1961). The effects of microinjections, into the nucleus tractus solitarius (NTS), of serotonin (5-HT) and 1-(m-chlorophenyl)-biguanide (CPBG), a potent 5-HT3 receptor agonist, on these reflex responses were studied in urethananesthetized rats. 5-HT (600 and 900 pmol) and CPBG (10-150 pmol) produced a dose-dependent inhibition of the atropine-sensitive bradycardiac component of the B-J reflex. The effect of both agonists was reversed by prior local microinjection of the 5-HT3 receptor antagonists zacopride (100 pmol) and ondansetron (100 pmol), but not by that of the 5-HT2 receptor antagonist ketanserin (10 pmol) or the mixed 5-HT1/5-HT2 receptor antagonist methysergide (100 pmol). In contrast, CPBG (150 pmol) did not affect the B-J reflex inhibition of lumbar sympathetic nerve discharge. These results show that stimulation of NTS 5-HT3 receptors produced an inhibition of the cardiovagal component of the B-J reflex without affecting its sympathetic component. Because the stimulation of these receptors also inhibits the cardiac component of the baroreflex, the present data suggest the participation of NTS 5-HT3 receptors in the mechanisms that modulate cardiac reflex responses elicited by messages from different vagal afferents.
- Published
- 1996
28. Medullary pathways of cardiovascular responses to 5-HT2 and 5-HT3 receptor stimulation in the rat nucleus tractus solitarius
- Author
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C. Sevoz, Raul Laguzzi, Michel Hamon, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Male ,Agonist ,medicine.medical_specialty ,Baroreceptor ,Microinjections ,medicine.drug_class ,[SDV]Life Sciences [q-bio] ,Blood Pressure ,Bicuculline ,5-HT3 receptor ,Rats, Sprague-Dawley ,chemistry.chemical_compound ,Kynurenic acid ,Heart Rate ,Internal medicine ,Solitary Nucleus ,medicine ,Animals ,Glutamate receptor antagonist ,biology ,General Neuroscience ,Solitary nucleus ,Rats ,Serotonin Receptor Agonists ,Amphetamine ,Endocrinology ,nervous system ,chemistry ,biology.protein ,Medulla oblongata ,circulatory and respiratory physiology - Abstract
As previously found for the baroreceptor reflex, microinjection of kynurenic acid (KYN, 2 nmol), a glutamate receptor antagonist, into the caudal ventrolateral medulla (CVL) blocked the hypotension and bradycardia elicited by microinjections of a 5-HT 2 receptor agonist, 2,5-dimethoxy-4-iodoamphetamine (DOI, 0.5 pmol) into the nucleus tractus solitarius (NTS). In addition, as previously observed with the sympathetic chemoreflex response, microinjections of KYN into the RVL blocked the increase in blood pressure elicited by microinjections of 1-m-(chlorophenyl)-biguanide (1200 pmol), a 5-HT 3 receptor agonist, into the NTS. These results suggest that medullary pathways involved in the responses to 5-HT 2 and 5-HT 3 receptor stimulation in the NTS are similar to those that mediate the baroceptor and chemoreceptor reflex responses, respectively.
- Published
- 1996
29. Cardiovascular effects of 5HT2 and 5HT3 receptor stimulation in the nucleus tractus solitarius of spontaneously hypertensive rats
- Author
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Raul Laguzzi and Nacera Merahi
- Subjects
Agonist ,Male ,medicine.medical_specialty ,Ketanserin ,medicine.drug_class ,Blood Pressure ,Rats, Inbred WKY ,5-HT3 receptor ,Heart Rate ,Internal medicine ,Rats, Inbred SHR ,medicine ,Solitary Nucleus ,Animals ,Molecular Biology ,Microinjection ,5-HT receptor ,biology ,Dose-Response Relationship, Drug ,business.industry ,General Neuroscience ,Solitary nucleus ,Receptor antagonist ,Rats ,Serotonin Receptor Agonists ,Amphetamine ,Endocrinology ,Receptors, Serotonin ,Hypertension ,biology.protein ,Neurology (clinical) ,business ,Developmental Biology ,Phenylbiguanide ,medicine.drug - Abstract
The effects of local application of 5-HT 2 - and 5-HT 3 -receptor agonists in the nucleus tractus solitarius (NTS) on the cardiovascular parameters were investigated in anaesthetized spontaneously hypertensive (SH) rats and their genetically normotensive precursors (WKY). Unilateral microinjection of picomolar doses of a 5HT 2 receptor agonist, 2,5-dimethoxy-3-bromo-amphetamine (DOB, 0.025 – 0.5 pmol), produced a dose-dependent hypotension and bradycardia in both SH and WKY rats. These effects could be prevented by prior local microinjection of a 5-HT 2 receptor antagonist, ketanserin (10 pmol). However, for both cardiovascular parameters, DOB was more potent in SH than in WKY rats. Thus, the dose-related responses to DOB were shifted to the left in SH as compared to WKY rats. Bilateral microinjection of the 5-HT 3 receptor agonist, phenylbiguanide (1.7 – 5 nmol), produced an increase in blood pressure and reduced the cardiovagal component of the baroreflex. These effects were not significantly different in SH and WKY rats. These data suggest that 5-HT 2 receptors, but not 5-HT 3 receptors, are supersensitive in the NTS of SH rats.
- Published
- 1995
30. Sleep changes induced by the local application of 5,7-dihydroxytryptamine into the nodose ganglia and aortic denervation in the rat
- Author
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Henri Gozlan, Hakan S. Orer, Raul Laguzzi, Anne Nosjean, Nacera Merahi, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,Baroreceptor ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Clinical Biochemistry ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,0302 clinical medicine ,MESH: Behavior, Animal ,Nervous System Physiological Phenomena ,MESH: Animals ,Aorta ,Denervation ,0303 health sciences ,MESH: Nervous System Physiological Phenomena ,Behavior, Animal ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Nodose Ganglion ,MESH: Aorta ,MESH: Rats, Inbred Strains ,MESH: 5,7-Dihydroxytryptamine ,Wakefulness ,Sleep Stages ,Sleep onset ,medicine.medical_specialty ,MESH: Sleep ,MESH: Rats ,5,7-Dihydroxytryptamine ,Serotonergic ,03 medical and health sciences ,MESH: Nodose Ganglion ,Physiology (medical) ,Internal medicine ,medicine ,Animals ,Circadian rhythm ,MESH: Denervation ,030304 developmental biology ,business.industry ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Rats, Inbred Strains ,MESH: Sleep Stages ,medicine.disease ,MESH: Male ,Rats ,Endocrinology ,business ,Sleep ,030217 neurology & neurosurgery ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Narcolepsy - Abstract
International audience; The effects of a bilateral microinjection of 5,7-dihydroxytryptamine (5,7-DHT) into the nodose ganglia and aortic denervation on the daily amounts of sleep/wake states were studied in rats. Both lesions produced an increase in paradoxical sleep and provoked the onset of paradoxical sleep episodes without slow-wave-sleep transition ("narcolepsy-like" paradoxical sleep episodes). The increase in paradoxical sleep observed after 5,7-DHT injection was more important than that of the aortic denervation. In addition, both 5,7-DHT-treated and aortic-denervated animals exhibited a delayed decrease in slow-wave sleep associated with an increase in wakefulness. These results show that the peripheral messages coming from aortic serotonergic afferent fibres to the nucleus tractus solitarius play a modulatory role in the daily expression of paradoxical sleep in rats.
- Published
- 1991
31. Cardiovascular effects of the local injection of 5,7-dihydroxytryptamine into the nodose ganglia and nucleus tractus solitarius in awake freely moving rats
- Author
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Nacera Merahi, Raul Laguzzi, C. M. Fattaccini, Anne Nosjean, Hakan S. Orer, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,Baroreceptor ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Blood Pressure ,MESH: Microinjections ,MESH: Nerve Degeneration ,MESH: Pressoreceptors ,chemistry.chemical_compound ,0302 clinical medicine ,Heart Rate ,MESH: Animals ,MESH: Heart Rate ,Medulla Oblongata ,0303 health sciences ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Chemistry ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Electroencephalography ,MESH: Blood Pressure ,Hydroxyindoleacetic Acid ,MESH: Electrooculography ,MESH: Rats, Inbred Strains ,MESH: 5,7-Dihydroxytryptamine ,Electrodes, Implanted ,Nodose Ganglion ,medicine.drug ,circulatory and respiratory physiology ,Serotonin ,medicine.medical_specialty ,MESH: Hemodynamics ,Microinjections ,MESH: Rats ,MESH: Reflex ,5,7-Dihydroxytryptamine ,Pressoreceptors ,Baroreflex ,Serotonergic ,MESH: Hydroxyindoleacetic Acid ,Injections ,MESH: Electromyography ,03 medical and health sciences ,MESH: Nodose Ganglion ,Internal medicine ,MESH: Medulla Oblongata ,Reflex ,MESH: Electroencephalography ,medicine ,Animals ,MESH: Injections ,Molecular Biology ,Microinjection ,Phenylephrine ,030304 developmental biology ,Electromyography ,Solitary nucleus ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Hemodynamics ,Rats, Inbred Strains ,MESH: Male ,Rats ,Electrooculography ,Endocrinology ,nervous system ,Nerve Degeneration ,MESH: Serotonin ,MESH: Electrodes, Implanted ,Neurology (clinical) ,Neuroscience ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,030217 neurology & neurosurgery ,Developmental Biology - Abstract
International audience; The role of the nucleus tractus solitarius (NTS) serotonergic afferents in cardiovascular (CV) regulation is yet to be established. However, several findings suggest that in this nucleus the serotonergic endings coming from the nodose ganglia (NG) are involved in the control of blood pressure (BP). The purpose of the present study was to identify the CV effects of the destruction of this NG-NTS serotonergic pathway. For that, the BP, BP variability (BPV) and heart rate (HR) effects of the local microinjection of 5,7-dihydroxytryptamine (5,7-DHT), into the NG and NTS were investigated in awake freely moving rats. The local degeneration of serotonergic elements was associated with a significant decrease in the 5-HT and 5-hydroxyindole acetic acid levels within the NG and NTS in 5,7-DHT treated rats. In addition, the microinjection of the neurotoxin in both structures produced a transient and significant increase in BP. This effect was of greater amplitude and associated with an increase in BPV in NG lesioned rats. These results may indicate that the NG-NTS serotonergic pathway participates in the transfer of the messages arising from the aortic baroreceptors. However, the vagal component of the baroreflex assessed with the phenylephrine test was not significantly modified in NG lesioned animals as compared to controls. Consequently, if the present data suggest that the NG-NTS serotonergic pathway plays a depressor role in BP regulation, its involvement in the reflex CV responses triggered by the stimulation of the aortic baroreceptors has yet to be established.
- Published
- 1991
32. Serotonergic projections from the nodose ganglia to the nucleus tractus solitarius: an immunohistochemical and double labeling study in the rat
- Author
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Anne Nosjean, Nacera Merahi, Jean-Jacques Puizillout, Catherine Buisseret-Delmas, Raul Laguzzi, Claude Compoint, Hakan S. Orer, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire de physiologie de la motricité, Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), CNRS LNB EI, Laboratoire de Neurobiologie (LNB), Centre National de la Recherche Scientifique (CNRS), and PERIGNON, Alain
- Subjects
Male ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,MESH: Neurons ,Axonal Transport ,0302 clinical medicine ,MESH: Vagus Nerve ,MESH: Axonal Transport ,MESH: Animals ,Horseradish Peroxidase ,Neurons ,0303 health sciences ,Medulla Oblongata ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Vagus Nerve ,Commissure ,MESH: Rats, Inbred Strains ,Immunohistochemistry ,medicine.anatomical_structure ,Medulla oblongata ,MESH: Gold ,Nodose Ganglion ,circulatory and respiratory physiology ,Serotonin ,MESH: Rats ,Central nervous system ,Biology ,Serotonergic ,03 medical and health sciences ,MESH: Nodose Ganglion ,MESH: Medulla Oblongata ,medicine ,Animals ,MESH: Horseradish Peroxidase ,030304 developmental biology ,Solitary nucleus ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,MESH: Immunohistochemistry ,Rats, Inbred Strains ,MESH: Male ,Rats ,nervous system ,Axoplasmic transport ,MESH: Serotonin ,Gold ,Neuroscience ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,030217 neurology & neurosurgery - Abstract
International audience; Possible projections of serotonin (5-HT)-immunoreactive neurons in the nodose ganglia (NG) to the nucleus tractus solitarius (NTS) were investigated in the rat using a double labeling method combining retrograde transport and 5-HT immunohistochemistry. After injection of a complex of colloidal gold-apo-horseradish peroxidase into the medio-caudal and commissural parts of the NTS, most of the 5-HT-immunoreactive neurons were found to be labelled by the gold complex. The present study provides direct evidence for the existence, in the rat, of a serotonergic NG-NTS system. This system may be involved in the regulation of blood pressure and vigilance states.
- Published
- 1990
33. MEDULLARY PATHWAYS OF CARDIOVASCULAR RESPONSES TO 5-HT2 AND 5-HT3 RECEPTOR STIMULATION IN THE RAT NUCLEUS TRACTUS SOLITARIUS
- Author
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Raul Laguzzi, C. Sevoz, Michel Hamon, and J B Lecharny
- Subjects
Pharmacology ,medicine.medical_specialty ,Nucleus tractus solitarius ,Endocrinology ,biology ,Medullary cavity ,Chemistry ,Internal medicine ,medicine ,biology.protein ,Pharmacology (medical) ,Stimulation ,5-HT3 receptor - Published
- 1997
34. Serotonin[sub 2] Receptors in the Nucleus Tractus Solitarius: Characterization and Role in the Baroreceptor Reflex Arc.
- Author
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Raul, Laguzzi
- Subjects
SEROTONIN ,SOLITARY nucleus ,SEROTONINERGIC mechanisms ,BAROREFLEXES - Abstract
Focuses on serotonin and the possible facilitatory influence of nucleus tractus solitarius (NTS) serotonergic afferents and receptors on the baroreceptor reflex arc. Effects of selective lesion of NTS serotonergic terminals; Cardiovascular effects of serotonin microinjection into the NTS.
- Published
- 2003
35. Cardiovascular effects of the microinjection of serotonin into the nucleus tractus solitarius involve 5-HT2 and 5-HT3 receptors, in the rat
- Author
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Hakan S. Orer, Raul Laguzzi, and Nacera Merahi
- Subjects
Pharmacology ,medicine.medical_specialty ,Endocrinology ,Nucleus tractus solitarius ,Chemistry ,Internal medicine ,medicine ,Serotonin ,Receptor ,Microinjection - Published
- 1990
36. Serotonin2Receptors in the Nucleus Tractus Solitarius: Characterization and Role in the Baroreceptor Reflex Arc
- Author
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Raul, Laguzzi
- Abstract
1. There is a general agreement concerning the key role of the baroreceptor reflex in blood pressure homeostasis. It is also well accepted that baroreceptor afferent messages are first integrated within the nucleus tractus solitarius (NTS) and that an excitatory amino acid, probably glutamate, is the principal neurotransmitter of corresponding afferents fibers. However, important points concerning the processing of baroreceptor messages within the NTS remain to be clarified, in particular the possible modulatory role of other neuroactive substances at this particular level in the medulla oblongata. 2. In this context, the present review focuses on serotonin, and the possible facilitatory influence of NTS serotonergic afferents and receptors on the baroreceptor reflex arc. Relevant pharmacological, electrophysiological, immunohistochemical, and biochemical data, are presented and discussed. They can be summarized as follows. 3. The selective destruction of the nodose ganglion-NTS serotonergic pathway produces a long-term increase in blood pressure variability, similar to that caused by baroreceptor denervation. 4. Microinjection of picomolar doses of 5-HT into the NTS elicits the typical responses of baroreceptor activation. 5. The cardiovascular effects elicited by local microinjections of specific agonists and antagonists into the NTS of intact rats and of animals that underwent nodose ganglionectomy indicate that the baroreceptor-like effects of locally administered 5-HT are mediated by the activation of postsynaptic 5-HT2receptors. 6. The medullary pathways which mediate NTS 5-HT2receptor-evoked responses are similar to those involved in the baroreceptor reflex arc. 7. Pharmacological and electrophysiological studies suggest that the cardiovascular effects of intra-NTS 5-HT involve the 5-HT2Areceptor subtype expressed by NTS barosensitive neurons that receive polysynaptic vagal afferents. 8. Intra-NTS microinjection of a subthreshold dose of DOI, a 5-HT2receptor agonist, which, on its own, does not produce any cardiovascular changes, significantly enhances the bradycardiac component of the baroreflex. 9. Altogether, the data summarized above show that, in the NTS, 5-HT acting at 5-HT2Areceptors exerts a facilitatory influence on the baroreceptor reflex, especially on the cardiac component of this reflex. 10. Convergent pharmacological and electrophysiological data indicate that, in the NTS, functional interactions between NMDA- and 5-HT2A-receptors coexpressed by the same neurons probably underlie the facilitatory influence of 5-HT upon the baroreceptor reflex. 11. Under physiological conditions, the 5-HT2Areceptor-mediated facilitatory modulation of the cardiovagal component of the baroreflex might be triggered by 5-HT released from nodose ganglion-NTS serotoninergic afferent neurons and/or for serotoninergic projections originating in raphe nuclei. The latter possibility might notably occur during recovery after physical exercise and/or during the “freezing” reaction in stressed animals.
- Published
- 2003
- Full Text
- View/download PDF
37. Effects of intraventricular injection of 6-hydroxydopamine in the developing kitten. 1. On the sleepwaking cycles
- Author
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Joëlle Adrien, Michel Hamon, Sylvie Bourgoin, and Raul Laguzzi
- Subjects
Serotonin ,medicine.medical_specialty ,animal structures ,Dopamine ,Sleep, REM ,Kitten ,Hydroxydopamines ,Norepinephrine ,Internal medicine ,biology.animal ,medicine ,Animals ,Receptors, Cholinergic ,Juvenile animal ,Wakefulness ,Molecular Biology ,Injections, Intraventricular ,Catecholaminergic ,Hydroxydopamine ,Behavior, Animal ,biology ,General Neuroscience ,Body Weight ,Age Factors ,Brain ,Organ Size ,Sleep in non-human animals ,Monoamine neurotransmitter ,Endocrinology ,Animals, Newborn ,nervous system ,Clomipramine ,Forebrain ,Cats ,Sleep Stages ,Neurology (clinical) ,Psychology ,Developmental Biology - Abstract
Summary Intraventricular 6-OHDA was injected in kittens at different stages of development, and the subsequent sleep polygram was analyzed, in order to determine the role of the catecholaminergic system in the ontogenesis of sleep regulations during the first and the second postnatal months. 6-OHDA, used with or without previous chlorimipramine treatment, led within a 10-day period to drastic reductions of the endogenous monoamines in the forebrain of all age groups. Although the neurotoxicity of 6-OHDA was almost constant among the different age groups, the effects on sleep depended on the age of the animals at the time of the injection. In the 5-week-old injected kittens, 6-OHDA affected PS according to an adult-like pattern. In the 3-week-old kittens, 6-OHDA alone (leading to both catecholamines and serotonin decreases) induced the same PS deficit as in the adult cat. In the 1- and 2-week-old kittens, neither 6-OHDA alone, nor 6-OHDA with previous chlorimipramine treatment, distrubed the sleep regulations. These data are compared to similar experiments performed in the adult cat. They are discussed in terms of sleep control ontogenesis. It is concluded that the catecholaminergic system plays no important role in the mechanisms of sleep regulation in the early postnatal period in the kitten, whereas its regulatory influence on PS is confirmed in the juvenile animal. The functional maturation of the catecholaminergic system in terms of sleep regulation is achieved between the third and the fifth week of postnatal life.
- Published
- 1979
38. Modulation of cardiovascular and electrocortical activity through serotonergic mechanisms in the nucleus tractus solitarius of the rat
- Author
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Donald J. Reis, William T. Talman, and Raul Laguzzi
- Subjects
Male ,Serotonin ,medicine.medical_specialty ,Metergoline ,Mean arterial pressure ,Baroreceptor ,Blood Pressure ,Baroreflex ,Serotonergic ,Cardiovascular Physiological Phenomena ,chemistry.chemical_compound ,Heart Rate ,Internal medicine ,Neural Pathways ,Heart rate ,Animals ,Medicine ,Molecular Biology ,Cerebral Cortex ,Brain Mapping ,Medulla Oblongata ,business.industry ,General Neuroscience ,Solitary nucleus ,Electroencephalography ,Rats, Inbred Strains ,Rats ,Endocrinology ,Blood pressure ,nervous system ,chemistry ,Anesthesia ,Neurology (clinical) ,business ,circulatory and respiratory physiology ,Developmental Biology - Abstract
The nucleus tractus solitarius (NTS) is an integral part of the baroreceptor reflex arc. Thus, stimulation of the NTS elicits changes in arterial pressure and heart rate as well as in numerous other physiologic parameters including electrocortical activity. Serotonin (5-HT), which has been implicated in cardiovascular and electrocortical control, is present in nerve terminals within the NTS. Therefore, this study was designed to determine whether 5-HT may effect that control within the NTS. Serotonin injected into the NTS of anesthetized rats produced marked changes in the EEG, arterial pressure, and heart rate. EEG activity changed from irregular 1-5 Hz, 350-500 microV waves with an overlying 13-15 Hz, low voltage rhythm to a regular, 5 Hz, 250-300 microV rhythm. The dose-dependent cardiovascular changes were maximal at a dose of 400 pmol which produced a fall of mean arterial pressure of 48 +/- 2 mm Hg from a baseline of 96 +/- 4 mm Hg and of heart rate of 90 +/- 9 bpm from a baseline of 400 +/- 18 bpm (n = 6; P less than 0.001). Both the cardiovascular and EEG effects of 5-HT injected into the NTS were blocked by the prior injection of the 5-HT antagonist metergoline at the same site. However, the bilateral microinjection of metergoline into the NTS did not affect the baroreceptor reflex. Thus, although serotonergic mechanisms in the NTS may be involved in the modulation of electrocortical and cardiovascular activity, they are not integral to the baroreceptor reflex arc.
- Published
- 1984
39. Effects of intraventricular injection of 6-hydroxydopamine in the developing kitten. II. On the central monoaminergic innervation
- Author
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Michel Hamon, Annette Dolphin, Joëlle Adrien, Raul Laguzzi, Sylvie Bourgoin, Joël Bockaert, and Francis Hery
- Subjects
Male ,Serotonin ,medicine.medical_specialty ,Dopamine ,Hypothalamus ,Caudate nucleus ,Hippocampus ,Kitten ,Hydroxydopamines ,Norepinephrine ,biology.animal ,Internal medicine ,Piriform cortex ,medicine ,Animals ,Receptors, Cholinergic ,Molecular Biology ,Injections, Intraventricular ,Cerebral Cortex ,biology ,General Neuroscience ,Olfactory tubercle ,Age Factors ,Brain ,Anatomy ,Receptors, Adrenergic ,medicine.anatomical_structure ,Endocrinology ,Animals, Newborn ,nervous system ,Cerebral cortex ,Forebrain ,Cats ,Raphe Nuclei ,Locus coeruleus ,Female ,Neurology (clinical) ,Adenylyl Cyclases ,Brain Stem ,Synaptosomes ,Developmental Biology - Abstract
Summary The intraventricular administration of 6-hydroxydopamine (6-OHDA) to kittens between 5 days and 4 months of age induced marked changes in the endogenous levels of DA, NE and 5-HT in various brain areas. In contrast to the well-known selective effect of 6-OHDA against catecholaminergic neurones in the rat, serotoninergic neurones were also markedly affected by 6-OHDA treatment in kittens; particularly in the hippocampus and the colliculi, 5-HT levels were markedly and permanently decreased after the intraventricular administration of 6-OHDA. A significant but less pronounced reduction in 5-HT levels was also noted in other areas such as the piriform cortex, the cerebral neocortex, the cerebellum and the septum. Only very discrete changes were detected in the caudate nucleus, the olfactory tubercle and the raphe area. The administration of chlorimipramine (10 mg/kg, i.p.) 1 h before 6-OHDA treatment completely prevented the effects of the neurotoxic agent on serotoninergic innervation. Marked regional differences were also noted concerning the effects of 6-OHDA treatment on dopaminergic neurones. Whereas DA levels in the raphe area and the hypothalamus were almost unaffected, they were permanently reduced by about 50% in the caudate nucleus and the olfactory tubercle after the intraventricular administration of 6-OHDA. In the caudate nucleus, the reduction was even much more pronounced (−90%) when 6-OHDA was administered during the first 3 postnatal weeks. In most forebrain areas (hippocampus, piriform cortex and cerebral neocortex) and in the cerebellum, NE levels were permanently reduced to about 10% of those of control kittens as soon as the third day following the intraventricular injection of 6-OHDA. In contrast, after a transient drop, NE levels in the lateral brain stem (containing the locus coeruleus) of 6-OHDA-treated kittens returned and even surpassed (+100%) those found in age-paired controls. Analyses of the characteristics of l -[ 3 H]NE uptake in synaptosomes indicated that 6-OHDA treatment resulted in both a striking loss of specific uptake sites in forebrain areas and a significant increase in the V max of the NE uptake process in synaptosomes from the lateral brain stem. However, in contrast to the rapid increase in NE levels, this change in V max occurred much later, since it was first detected at more than one month after 6-OHDA treatment. This delay suggests that the doubling in NE levels occurring for the first month following the intraventricular administration of 6-OHDA simply resulted from an increased accumulation of the catecholamine in noradrenergic terminals in the lateral brain stem. Later on, the change in V max might indicate a sprouting of new noradrenergic terminals in the vicinity of the locus coeruleus area. The intraventricular administration of 6-OHDA resulted in a significant increase in the maximal stimulatory effect of l -isoproterenol on adenylate cyclase activity in homogenates of the cerebral cortex and the lateral brain stem. Therefore, not only the degeneration (in the cerebral cortex) but also the proliferation (in the lateral brain stem) of noradrenergic terminals were associated with an increase in the density of beta-adrenergic receptors. These results are discussed in relation to the possible function of the noradrenergic sprouts in the lateral brain stem.
- Published
- 1979
40. Serotonergic Mechanisms in the Nucleus Tractus Solitarius May Regulate Blood Pressure and Behaviour in the Rat
- Author
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Donald J. Reis, William T. Talman, and Raul Laguzzi
- Subjects
medicine.medical_specialty ,Metergoline ,Baroreceptor ,business.industry ,General Medicine ,Serotonergic ,chemistry.chemical_compound ,Blood pressure ,Endocrinology ,nervous system ,chemistry ,Anesthesia ,Internal medicine ,Microinjections ,medicine ,Serotonin ,business ,Microinjection ,Acetylcholine ,medicine.drug - Abstract
1. Highly localized microinjections of serotonin into the nucleus tractus solitarius in rats produced dose-dependent hypotension and bradycardia and electroencephalogram (EEG) changes consistent with an alerting response. 2. Microinjection of the serotinin antagonist metergoline blocked the cardiovascular and EEG effects of serotonin but did not affect the same responses elicited by the microinjection of l-glutamate. 3. Microinjections of l-glutamate produced similar effects; acetylcholine, which lowered arterial pressure and heart rate, did not affect the EEG. 4. Bilateral injections of metergoline into the nucleus tractus solitarius occasionally produced a rise in arterial pressure but did not affect the baroreceptor reflex. 5. Serotonin may integrate cardiovascular and behavioural responses mediated by the nucleus tractus solitarius. 6. Neuronal populations within the nucleus tractus solitarius may be neurochemically and functionally differentiated.
- Published
- 1982
41. Effects of serotonin synthesis inhibition on sleep in hippocampectomized rats
- Author
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Raul Laguzzi
- Subjects
Male ,Serotonin ,medicine.medical_specialty ,Serotonin synthesis ,Sleep, REM ,Hippocampus ,Internal medicine ,medicine ,Insomnia ,Animals ,Motor activity ,Molecular Biology ,Sleep Stages ,Dose-Response Relationship, Drug ,business.industry ,General Neuroscience ,Fenclonine ,Sleep in non-human animals ,Rats ,Endocrinology ,Serotonin Antagonists ,Neurology (clinical) ,medicine.symptom ,Sleep ,business ,Developmental Biology - Abstract
In adult rats an anterodorsal bilateral hippocampectomy produced an increase in motor activity without modification of the amount of the different sleep stages. In hippocampectomized ratsp-chlorophenylalanine produced an insomnia which can be reversed by 5-HTP. These results show that the insomnia produced by brain serotonin depletion is not a result of the hyperactivity produced by the treatments which cause such depletion.
- Published
- 1982
42. Cardiovascular changes induced by the local application of glutamate-related drugs in the rat nucleus tractus solitarii
- Author
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Eric Le Galloudec, Nacera Merahi, and Raul Laguzzi
- Subjects
Male ,Glutamic Acid ,Kainate receptor ,Blood Pressure ,Pharmacology ,Kynurenic Acid ,Cardiovascular System ,Receptors, N-Methyl-D-Aspartate ,Cardiovascular Physiological Phenomena ,chemistry.chemical_compound ,Glutamatergic ,Kynurenic acid ,Glutamates ,Heart Rate ,Medicine ,Animals ,Molecular Biology ,Medulla Oblongata ,Vagovagal reflex ,business.industry ,General Neuroscience ,Solitary nucleus ,Glutamate receptor ,Rats, Inbred Strains ,Rats ,Receptors, Neurotransmitter ,nervous system ,chemistry ,2-Amino-5-phosphonovalerate ,Anesthesia ,Reflex ,NMDA receptor ,Neurology (clinical) ,business ,circulatory and respiratory physiology ,Developmental Biology - Abstract
The effects of the local application of drugs acting on glutamatergic receptors in the nucleus tractus solitarii (NTS) were investigated in anesthetized rats. Unilateral microinjection of agonists ( l -glutamate, l -aspartate, N- methyl - d - aspartate (NMDA) and quisqualate) produced a dose-dependent hypotension and bradycardia. The effects of NMDA were prevented by low doses of the selective NMDA-receptor antagonist, 2-amino-5-phosphonovalerate (2-APV), or by the mixed NMDA/kainate antagonist, γ- d -glutamylglycine. The response to all agonists and the bradycardia which was elicited in response to the intravenous administration of phenyleprine (vagal reflex response) could be prevented by the local microinjection of the glutamate antagonists kynurenic acid (3 nmol) and 2-APV (10 nmol) into the NTS. The present data suggest that in the NTS, NMDA and quisqualate receptors are implicated in blood pressure reflex regulation.
- Published
- 1989
43. Increase in paradoxical sleep after destruction of serotoninergic innervation in the nucleus tractus solitarius of the rat
- Author
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A. Nosjean, Raul Laguzzi, Michel Arluison, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), Laboratoire de Cytologie, Institut des Neurosciences, URA CNRS 1488, Universite Paris VI, France, Institut des Neurosciences (IDN), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), and PERIGNON, Alain
- Subjects
Male ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Blood Pressure ,0302 clinical medicine ,MESH: Animals ,Medulla Oblongata ,0303 health sciences ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,General Neuroscience ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Blood Pressure ,Immunohistochemistry ,Sleep in non-human animals ,MESH: Rats, Inbred Strains ,MESH: 5,7-Dihydroxytryptamine ,Circadian Rhythm ,medicine.anatomical_structure ,Sleep Stages ,medicine.symptom ,Sleep onset ,Serotonin ,MESH: Rats ,5,7-Dihydroxytryptamine ,Sleep, REM ,Serotonergic ,Lesion ,03 medical and health sciences ,MESH: Medulla Oblongata ,medicine ,Animals ,Circadian rhythm ,MESH: Circadian Rhythm ,Wakefulness ,5-HT receptor ,030304 developmental biology ,business.industry ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Rats, Inbred Strains ,MESH: Immunohistochemistry ,MESH: Sleep Stages ,MESH: Sleep, REM ,MESH: Male ,Rats ,MESH: Wakefulness ,nervous system ,MESH: Serotonin ,business ,Nucleus ,Neuroscience ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,030217 neurology & neurosurgery - Abstract
International audience; The evolution of paradoxical sleep, slow-wave sleep and arterial pressure was studied following microinjection of 5,7-dihydroxytryptamine in the nucleus tractus solitarius in rats. The extent of the lesions was assessed using immunohistochemistry for serotonin. Global lesions of serotoninergic nerve terminals of the intermediate and commissural regions of the nucleus produced an important and long-lasting increase in paradoxical sleep (+50-70%), a decrease in slow-wave sleep (-20%) and a moderate increase of arterial pressure during all states of the sleep-wake cycle. In addition, more discrete lesions indicated that only the lesion of the area near the obex produced the longer term increase of paradoxical sleep whereas only the lesion of the commissural region of the nucleus produced the long-term decrease of slow-wave sleep. These data demonstrate that serotoninergic projections to the nucleus tractus solitarius exert a regulatory influence upon the specific mechanisms responsible for paradoxical sleep and slow-wave sleep in rats. Furthermore, they suggest that serotonin within the nucleus tractus solitarius plays an important role in the homeostatic cardiovascular and sleep-wake-cycle regulation in rats.
- Published
- 1987
44. Cardiovascular changes during the sleep-wake cycle in spontaneous hypertensive rats and in their genetically normotensive precursors
- Author
-
Jean M. Meunier, Raul Laguzzi, J. Lacombe, Anne Nosjean, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM), and PERIGNON, Alain
- Subjects
Male ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Clinical Biochemistry ,MESH: Rats, Inbred SHR ,[SDV.NEU.PC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,Hemodynamics ,Blood Pressure ,030204 cardiovascular system & hematology ,Rats, Inbred WKY ,0302 clinical medicine ,Heart Rate ,Rats, Inbred SHR ,Heart rate variability ,MESH: Animals ,MESH: Heart Rate ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,MESH: Blood Pressure ,MESH: Rats, Inbred Strains ,medicine.anatomical_structure ,Wakefulness ,psychological phenomena and processes ,MESH: Rats, Inbred WKY ,Blood vessel ,medicine.medical_specialty ,MESH: Rats ,MESH: Sleep ,Arousal ,03 medical and health sciences ,Species Specificity ,Physiology (medical) ,Internal medicine ,Heart rate ,medicine ,Animals ,MESH: Species Specificity ,Circadian rhythm ,business.industry ,[SDV.NEU.NB] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,Rats, Inbred Strains ,MESH: Male ,Rats ,MESH: Wakefulness ,Blood pressure ,Endocrinology ,Sleep ,business ,030217 neurology & neurosurgery ,[SDV.NEU.SC] Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences - Abstract
International audience; Blood pressure and heart rate were recorded in spontaneously hypertensive rats (SH) and in their genetically normotensive precursors (WKY) during the sleep-wake cycle using a computer-assisted method. Similar results were obtained in both strains: (a) No significant difference was observed in blood pressure values between slow-wave-sleep (SWS) and the last 2 min of the preceding wakefulness (W) episode within the complete cycle; blood pressure then increased during PS. (b) Heart rate values during SWS were significantly lower than those computed for W; a further fall of heart rate was observed during paradoxical sleep (PS) only in hypertensive rats. (c) During SWS the blood pressure and heart rate variability was significantly lower than during W and PS. In addition, blood pressure variability values during the three sleep-wake states were lower in hypertensive than in normotensive rats. These data suggest that there are no qualitative differences in the mechanisms that control circulation during sleep in normotensive and spontaneous hypertensive rats.
- Published
- 1988
45. Effects of intraventricular injection of 6-hydroxydopamine in the developing kitten. III. Histochemical fluorescence and radioautographic studies of the noradrenaline hyperinnervation in the pons
- Author
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Sylvie Bourgoin, Iroudayanadin S. de la Manche, Raul Laguzzi, Michel Arluison, Joe¨lle Adrien, and Michel Hamon
- Subjects
medicine.medical_specialty ,Aging ,Biology ,Kitten ,Norepinephrine ,Hydroxydopamines ,Internal medicine ,biology.animal ,Pons ,medicine ,Neurotoxin ,Animals ,Molecular Biology ,Injections, Intraventricular ,Cerebral Cortex ,Neurons ,Hydroxydopamine ,General Neuroscience ,Anatomy ,Axons ,Nerve Regeneration ,Endocrinology ,Monoamine neurotransmitter ,medicine.anatomical_structure ,nervous system ,Microscopy, Fluorescence ,Cerebral cortex ,Cats ,Locus coeruleus ,Autoradiography ,Neurology (clinical) ,Developmental Biology ,medicine.drug - Abstract
In the present study, using neonatal intraventricular injections of 6-hydroxydopamine (6-OHDA) and the fluorescence histochemical method for monoamines, it is observed that an extensive plexus of noradrenaline (NA) fibres develops in the pontine region of the cat brain subsequently to the neonatal destruction of the ascending NA bundles and of the NA innervation in the cerebral cortex by the neurotoxin. This plexus is only partly conserved 10 months after the 6-OHDA treatment. Generally, only a limited number of NA perikarya degenerate in the region of the locus coeruleus, the others (nucleus subcoeruleus senso lato) exhibiting the same strong fluorescence as the new NA fibres. Using the radioautographic method after intraventricular injections of [3H]NA, our work demonstrates also the transient disappearance (at least one month) of the uptake of [3H]NA in the pons, whose NA cell bodies and nerve terminals are no longer labeled in the same number as in control animals. The possibility of again labeling significantly NA perikarya and numerous nerve terminals occurred between 3 and 5 months of age, probably indicating both a re-establishment of normal uptake properties in the preserved NA perikarya and nerve terminals and some maturation of the uptake mechanisms in the abnormal NA fibres of the pons. This last observation is at variance with data from newborn animals showing that the uptake of NA develops in parallel with the accumulation of endogenous NA in catecholamine nerve terminals. The present results, however, do corroborate and complement previous biochemical data obtained in the cat after neonatal injection of 6-OHDA.
- Published
- 1980
46. Computer analysis of cardiovascular changes during sleep-wake cycle in Sprague-Dawley rats
- Author
-
J. Lacombe, J. M. Meunier, Anne Nosjean, Raul Laguzzi, Neuropsychopharmacologie moléculaire, cellulaire et fonctionnelle, and Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut National de la Santé et de la Recherche Médicale (INSERM)
- Subjects
Male ,Periodicity ,MESH: Periodicity ,Physiology ,[SDV.NEU.NB]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Neurobiology ,MESH: Monitoring, Physiologic ,Blood Pressure ,MESH: Signal Processing, Computer-Assisted ,0302 clinical medicine ,Heart Rate ,Reference Values ,MESH: Animals ,MESH: Heart Rate ,Slow-wave sleep ,0303 health sciences ,education.field_of_study ,CATS ,[SDV.NEU.PC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Psychology and behavior ,MESH: Reference Values ,[SDV.NEU.SC]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC]/Cognitive Sciences ,Signal Processing, Computer-Assisted ,MESH: Blood Pressure ,MESH: Rats, Inbred Strains ,Wakefulness ,Cardiology and Cardiovascular Medicine ,medicine.medical_specialty ,MESH: Sleep ,MESH: Rats ,Population ,Rapid eye movement sleep ,Biology ,MESH: Cardiovascular Physiological Phenomena ,Cardiovascular Physiological Phenomena ,MESH: Electromyography ,03 medical and health sciences ,Physiology (medical) ,Internal medicine ,Heart rate ,medicine ,Animals ,Circadian rhythm ,education ,Monitoring, Physiologic ,030304 developmental biology ,Electromyography ,Rats, Inbred Strains ,MESH: Male ,Rats ,Surgery ,MESH: Wakefulness ,Endocrinology ,Blood pressure ,Sleep ,030217 neurology & neurosurgery - Abstract
International audience; Blood pressure (BP) and heart rate (HR) were recorded in seven Sprague-Dawley rats during a total of 491 normal sleep-wake cycles with the use of a computer-assisted method developed for this study. Significant changes of BP, HR, and BP variability (BPV) were found between the three states within the cycle, i.e., wakefulness (W), slow-wave sleep (SWS), and paradoxical sleep (PS). The highest BP, BPV, and HR values were found during W. Then all cardiovascular (CV) variables fell during SWS, whereas BP and BPV rose again during PS. The fall of BPV observed during SWS was the most important CV change observed within the cycle. These state-dependent CV changes suggest that, in the rat, circulation during the sleep-wake cycle is controlled by the same central factors that operate in cats. In addition, significant BP and HR modifications between different cycles have been found. On the other hand, BP and HR differences between animals were also observed. The latter differences were found to be stable across the states, but no significant relation was found between BP and HR within any state. Thus the present data also suggest that BP and HR measurements are influenced not only by state-dependent factors but also by at least three different factors that are each independent of the state: one leads to BP and HR values that are influenced by the cycle the animal is in and the other two influence, respectively, the ranking of the individual's BP and HR levels within the population.
- Published
- 1988
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