251 results on '"Krause EG"'
Search Results
2. Synthesis and cardiotonic activity of 6-substituted 5-cyano-(3,4′-bipyridine)-1′-oxides and related compounds: molecular structure of 5-cyano-6-morpholino-(3,4′-bipyridine)-1′-oxide (AWD 122–239)
- Author
-
Klauschenz, E, primary, Hagen, V, additional, Wiesner, B, additional, Hagen, A, additional, Reck, G, additional, and Krause, EG, additional
- Published
- 1994
- Full Text
- View/download PDF
3. Curating 'the good story': Care as representative performance in Danish veteran rehabilitation.
- Author
-
Krause EG, Christensen U, and Svendsen MN
- Abstract
In this article, we explore the intricacies of veteran care and show how care practices come to incorporate veterans' 'self-performances' to raise political attention and funding for future rehabilitation activities. By bringing into dialogue theories of care and theories of performance and representation, we illustrate how a seemingly classic form of care-veteran rehabilitation-takes the form of representative performance. Drawing on ethnographic fieldwork and interviews with the Danish Invictus Games team, we demonstrate how politics, research and TV documentaries are integrated into veteran care practices. Through this integration, mentally wounded veterans, while performing 'themselves' for shifting audiences with shifting agendas, come to assume the roles of both caregivers and care receivers. Crucially, we highlight that wounded veterans, while undertaking their personal rehabilitation journey, are curated into and (un)willingly positioned as representatives of others. By showing how caring for wounded veterans goes hand in hand with caring for fictive, future wounded veterans and for political, research and media agendas, this article offers new ways of thinking of and with care., (© 2024 The Author(s). Sociology of Health & Illness published by John Wiley & Sons Ltd on behalf of Foundation for the Sociology of Health & Illness.)
- Published
- 2024
- Full Text
- View/download PDF
4. Optical perturbation of Agtr1a-containing neurons and afferents within the caudal nucleus of the solitary tract modulates sodium intake.
- Author
-
Baumer-Harrison C, Patel S, Scott KA, Krause EG, and de Kloet AD
- Subjects
- Animals, Male, Drinking physiology, Drinking drug effects, Neurons, Afferent physiology, Neurons, Afferent metabolism, Optogenetics, Sodium Chloride pharmacology, Solitary Nucleus metabolism, Solitary Nucleus physiology, Solitary Nucleus drug effects, Receptor, Angiotensin, Type 1 metabolism, Neurons metabolism, Neurons physiology
- Abstract
Angiotensin-II (Ang-II) production is driven by deviations in blood volume and osmolality, and serves the role of regulating blood pressure and fluid intake to maintain cardiovascular and hydromineral homeostasis. These actions are mediated by Ang-II acting on its type 1a receptor (AT1aR) within the central nervous system and periphery. Of relevance, AT1aR are expressed on sensory afferents responsible for conveying cardiovascular information to the nucleus of the solitary tract (NTS). We have previously determined that optical excitation of neurons and vagal afferents within the NTS that express AT1aR (referred to as NTS
AT1aR ) mimics the perception of increased vascular stretch and induces compensatory responses to restore blood pressure. Here, we test whether NTSAT1aR are also involved in the modulation of water and sodium intake. We directed the light-sensitive excitatory channelrhodopsin-2 (ChR2) or inhibitory halorhodopsin (Halo) to Agtr1a-containing neurons and measured water and sodium chloride (NaCl) intake in the presence and absence of optical stimulation within the NTS during various challenges to fluid homeostasis. Optical perturbation of NTSAT1aR modulates NaCl intake, such that excitation attenuates, whereas inhibition increases intake. This effect is only observed in the water-deprived condition, suggesting that NTSAT1aR are involved in the regulation of sodium intake during an imbalance in both the intracellular and extracellular fluid compartments. Furthermore, optical excitation of NTSAT1aR increases c-Fos expression within oxytocinergic neurons of the paraventricular nucleus of the hypothalamus (PVN), indicating that the regulation of sodium intake by NTSAT1aR may be mediated by oxytocin. Collectively, these results reveal that NTSAT1aR are sufficient and necessary to modulate sodium intake relative to perceived changes in vascular stretch., (Copyright © 2024. Published by Elsevier Inc.)- Published
- 2024
- Full Text
- View/download PDF
5. Angiotensin-(1-5) is a Potent Endogenous Angiotensin AT 2 -Receptor Agonist.
- Author
-
Souza-Silva IM, Peluso AA, Elsaafien K, Nazarova AL, Assersen KB, Rodrigues-Ribeiro L, Mohammed M, Rodrigues AF, Nawrocki A, Jakobsen LA, Jensen P, de Kloet AD, Krause EG, Borgo MD, Maslov I, Widdop R, Santos RA, Bader M, Larsen M, Verano-Braga T, Katritch V, Sumners C, and Steckelings UM
- Abstract
Background: The renin-angiotensin system involves many more enzymes, receptors and biologically active peptides than originally thought. With this study, we investigated whether angiotensin-(1-5) [Ang-(1-5)], a 5-amino acid fragment of angiotensin II, has biological activity, and through which receptor it elicits effects., Methods: The effect of Ang-(1-5) (1µM) on nitric oxide release was measured by DAF-FM staining in human aortic endothelial cells (HAEC), or Chinese Hamster Ovary (CHO) cells stably transfected with the angiotensin AT
2 -receptor (AT2 R) or the receptor Mas. A potential vasodilatory effect of Ang-(1-5) was tested in mouse mesenteric and human renal arteries by wire myography; the effect on blood pressure was evaluated in normotensive C57BL/6 mice by Millar catheter. These experiments were performed in the presence or absence of a range of antagonists or inhibitors or in AT2 R-knockout mice. Binding of Ang-(1-5) to the AT2 R was confirmed and the preferred conformations determined by in silico docking simulations. The signaling network of Ang-(1-5) was mapped by quantitative phosphoproteomics., Results: Key findings included: (1) Ang-(1-5) induced activation of eNOS by changes in phosphorylation atSer1177 eNOS andTyr657 eNOS and thereby (2) increased NO release from HAEC and AT2 R-transfected CHO cells, but not from Mas-transfected or non-transfected CHO cells. (3) Ang-(1-5) induced relaxation of preconstricted mouse mesenteric and human renal arteries and (4) lowered blood pressure in normotensive mice - effects which were respectively absent in arteries from AT2 R-KO or in PD123319-treated mice and which were more potent than effects of the established AT2 R-agonist C21. (5) According to in silico modelling, Ang-(1-5) binds to the AT2 R in two preferred conformations, one differing substantially from where the first five amino acids within angiotensin II bind to the AT2 R. (6) Ang-(1-5) modifies signaling pathways in a protective RAS-typical way and with relevance for endothelial cell physiology and disease., Conclusions: Ang-(1-5) is a potent, endogenous AT2 R-agonist.- Published
- 2024
- Full Text
- View/download PDF
6. Alleviating Hypertension by Selectively Targeting Angiotensin Receptor-Expressing Vagal Sensory Neurons.
- Author
-
Baumer-Harrison C, Elsaafien K, Johnson DN, Peñaloza Aponte JD, de Araujo A, Patel S, Bruce EB, Harden SW, Frazier CJ, Scott KA, de Lartigue G, Krause EG, and de Kloet AD
- Subjects
- Mice, Male, Female, Animals, Solitary Nucleus physiology, Sensory Receptor Cells, Blood Pressure physiology, Phenylephrine pharmacology, Ion Channels, Desoxycorticosterone Acetate pharmacology, Hypertension, Red Fluorescent Protein
- Abstract
Cardiovascular homeostasis is maintained, in part, by neural signals arising from arterial baroreceptors that apprise the brain of blood volume and pressure. Here, we test whether neurons within the nodose ganglia that express angiotensin type-1a receptors (referred to as NG
AT1aR ) serve as baroreceptors that differentially influence blood pressure (BP) in male and female mice. Using Agtr1a -Cre mice and Cre-dependent AAVs to direct tdTomato to NGAT1aR , neuroanatomical studies revealed that NGAT1aR receive input from the aortic arch, project to the caudal nucleus of the solitary tract (NTS), and synthesize mechanosensitive ion channels, Piezo1/2 To evaluate the functionality of NGAT1aR , we directed the fluorescent calcium indicator (GCaMP6s) or the light-sensitive channelrhodopsin-2 (ChR2) to Agtr1a -containing neurons. Two-photon intravital imaging in Agtr1a -GCaMP6s mice revealed that NGAT1aR couple their firing to elevated BP, induced by phenylephrine (i.v.). Furthermore, optical excitation of NGAT1aR at their soma or axon terminals within the caudal NTS of Agtr1a -ChR2 mice elicited robust frequency-dependent decreases in BP and heart rate, indicating that NGAT1aR are sufficient to elicit appropriate compensatory responses to vascular mechanosensation. Optical excitation also elicited hypotensive and bradycardic responses in ChR2-expressing mice that were subjected to deoxycorticosterone acetate (DOCA)-salt hypertension; however, the duration of these effects was altered, suggestive of hypertension-induced impairment of the baroreflex. Similarly, increased GCaMP6s fluorescence observed after administration of phenylephrine was delayed in mice subjected to DOCA-salt or chronic delivery of angiotensin II. Collectively, these results reveal the structure and function of NGAT1aR and suggest that such neurons may be exploited to discern and relieve hypertension., Competing Interests: The authors declare no competing financial interests., (Copyright © 2024 the authors.)- Published
- 2024
- Full Text
- View/download PDF
7. ACE2 overexpression in corticotropin-releasing-hormone cells offers protection against pulmonary hypertension.
- Author
-
Oliveira AC, Karas MM, Alves M, He J, de Kloet AD, Krause EG, Richards EM, Bryant AJ, and Raizada MK
- Abstract
Background: Pulmonary hypertension (PH), characterized by elevated pulmonary pressure and right heart failure, is a systemic disease involving inappropriate sympathetic activation and an impaired gut-brain-lung axis. Global overexpression of angiotensin converting enzyme 2 (ACE2), a cardiopulmonary protective enzyme of the renin-angiotensin system, attenuates PH induced by chronic hypoxia. Neurons within the paraventricular nucleus of the hypothalamus (PVN) that synthesize corticotropin-releasing hormone (CRH) are activated by stressors, like hypoxia, and this activation augments sympathetic outflow to cardiovascular tissues. These data coupled with our observations that ACE2 overexpression in CRH cells (CRH-ACE2KI mice) decreases anxiety-like behavior via suppression of hypothalamic-pituitary-adrenal (HPA) axis activity by decreasing CRH synthesis, led us to hypothesize that selective ACE2 overexpression in CRH neurons would protect against hypoxia-induced PH., Methods: CRH-ACE2KI and WT male and female mice were exposed to chronic hypoxia (10%O2) or normoxia (21%O2) for 4 weeks in a ventilated chamber with continuous monitoring of oxygen and carbon dioxide concentrations ( n = 7-10/group). Pulmonary hemodynamics were measured with Millar pressure catheters then tissues were collected for histological analyses., Results: Chronic hypoxia induced a significant increase (36.4%) in right ventricular (RV) systolic pressure (RVSP) in WT mice, which was not observed in CRH-ACE2KI mice. No significant differences in RVSP were observed between male and female mice in any of the groups., Conclusion: Overexpression of ACE2 in CRH cells was protective against hypoxia-induced PH. Since the majority of expression of CRH is in brain nuclei such as paraventricular nucleus of the hypothalamus (PVN) and/or central nucleus of the amygdala (CeA) these data indicate that the protective effects of ACE2 are, at least in part, centrally mediated. This contributes to the systemic nature of PH disease and that CRH neurons may play an important role in PH., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Oliveira, Karas, Alves, He, de Kloet, Krause, Richards, Bryant and Raizada.)
- Published
- 2023
- Full Text
- View/download PDF
8. Mechanosensation of the heart and gut elicits hypometabolism and vigilance in mice.
- Author
-
Scott KA, Tan Y, Johnson DN, Elsaafien K, Baumer-Harrison C, Eikenberry SA, Sa JM, de Lartigue G, de Kloet AD, and Krause EG
- Abstract
Interoception broadly refers to awareness of one's internal milieu. Vagal sensory afferents monitor the internal milieu and maintain homeostasis by engaging brain circuits that alter physiology and behavior. While the importance of the body-to-brain communication that underlies interoception is implicit, the vagal afferents and corresponding brain circuits that shape perception of the viscera are largely unknown. Here, we use mice to parse neural circuits subserving interoception of the heart and gut. We determine vagal sensory afferents expressing the oxytocin receptor, hereafter referred to as NDG
Oxtr , send projections to the aortic arch or stomach and duodenum with molecular and structural features indicative of mechanosensation. Chemogenetic excitation of NDGOxtr significantly decreases food and water consumption, and remarkably, produces a torpor-like phenotype characterized by reductions in cardiac output, body temperature, and energy expenditure. Chemogenetic excitation of NDGOxtr also creates patterns of brain activity associated with augmented hypothalamic-pituitary-adrenal axis activity and behavioral indices of vigilance. Recurrent excitation of NDGOxtr suppresses food intake and lowers body mass, indicating that mechanosensation of the heart and gut can exert enduring effects on energy balance. These findings suggest that the sensation of vascular stretch and gastrointestinal distention may have profound effects on whole body metabolism and mental health., Competing Interests: Competing interest declaration: The authors declare no competing interests.- Published
- 2023
- Full Text
- View/download PDF
9. Sodium Intake and Disease: Another Relationship to Consider.
- Author
-
Baumer-Harrison C, Breza JM, Sumners C, Krause EG, and de Kloet AD
- Subjects
- Humans, Appetite physiology, Sodium Chloride, Dietary adverse effects, Sodium, Taste physiology, Hypertension etiology
- Abstract
Sodium (Na
+ ) is crucial for numerous homeostatic processes in the body and, consequentially, its levels are tightly regulated by multiple organ systems. Sodium is acquired from the diet, commonly in the form of NaCl (table salt), and substances that contain sodium taste salty and are innately palatable at concentrations that are advantageous to physiological homeostasis. The importance of sodium homeostasis is reflected by sodium appetite, an "all-hands-on-deck" response involving the brain, multiple peripheral organ systems, and endocrine factors, to increase sodium intake and replenish sodium levels in times of depletion. Visceral sensory information and endocrine signals are integrated by the brain to regulate sodium intake. Dysregulation of the systems involved can lead to sodium overconsumption, which numerous studies have considered causal for the development of diseases, such as hypertension. The purpose here is to consider the inverse-how disease impacts sodium intake, with a focus on stress-related and cardiometabolic diseases. Our proposition is that such diseases contribute to an increase in sodium intake, potentially eliciting a vicious cycle toward disease exacerbation. First, we describe the mechanism(s) that regulate each of these processes independently. Then, we highlight the points of overlap and integration of these processes. We propose that the analogous neural circuitry involved in regulating sodium intake and blood pressure, at least in part, underlies the reciprocal relationship between neural control of these functions. Finally, we conclude with a discussion on how stress-related and cardiometabolic diseases influence these circuitries to alter the consumption of sodium.- Published
- 2023
- Full Text
- View/download PDF
10. Intrahypothalamic effects of oxytocin on PVN CRH neurons in response to acute stress.
- Author
-
Pati D, Krause EG, and Frazier CJ
- Abstract
Much of the centrally available oxytocin (OT) is synthesized in magnocellular neurons located in the paraventricular nucleus of the hypothalamus. This same area is home to parvocellular corticotropin-releasing hormone (CRH) synthesizing neurons that regulate activation of the hypothalamic-pituitary-adrenal (HPA) axis. A large body of data indicates that complex interactions between these systems inextricably link central OT signaling with the neuroendocrine response to stress. This review focuses on a small but diverse set of cellular and synaptic mechanisms that have been proposed to underlie intrahypothalamic OT/CRF interactions during the response to acute stress., Competing Interests: Conflict of Interest None declared. Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
- Published
- 2022
- Full Text
- View/download PDF
11. Oxytocin and cardiometabolic interoception: Knowing oneself affects ingestive and social behaviors.
- Author
-
Smith JA, Eikenberry SA, Scott KA, Baumer-Harrison C, de Lartigue G, de Kloet AD, and Krause EG
- Abstract
Maintaining homeostasis while navigating one's environment involves accurately assessing and interacting with external stimuli while remaining consciously in tune with internal signals such as hunger and thirst. Both atypical social interactions and unhealthy eating patterns emerge as a result of dysregulation in factors that mediate the prioritization and attention to salient stimuli. Oxytocin is an evolutionarily conserved peptide that regulates attention to exteroceptive and interoceptive stimuli in a social environment by functioning in the brain as a modulatory neuropeptide to control social behavior, but also in the periphery as a hormone acting at oxytocin receptors (Oxtr) expressed in the heart, gut, and peripheral ganglia. Specialized sensory afferent nerve endings of Oxtr-expressing nodose ganglia cells transmit cardiometabolic signals via the Vagus nerve to integrative regions in the brain that also express Oxtr(s). These brain regions are influenced by vagal sensory pathways and coordinate with external events such as those demanding attention to social stimuli, thus the sensations related to cardiometabolic function and social interactions are influenced by oxytocin signaling. This review investigates the literature supporting the idea that oxytocin mediates the interoception of cardiovascular and gastrointestinal systems, and that the modulation of this awareness likewise influences social cognition. These concepts are then considered in relation to Autism Spectrum Disorder, exploring how atypical social behavior is comorbid with cardiometabolic dysfunction., (Copyright © 2022 Elsevier Ltd. All rights reserved.)
- Published
- 2022
- Full Text
- View/download PDF
12. A Novel Organ-Specific Approach to Selectively Target Sensory Afferents Innervating the Aortic Arch.
- Author
-
Elsaafien K, Harden SW, Johnson DN, Kimball AK, Sheng W, Smith JA, Scott KA, Frazier CJ, de Kloet AD, and Krause EG
- Abstract
The brain maintains cardiovascular homeostasis, in part, via the arterial baroreflex which senses changes in blood pressure (BP) at the level of the aortic arch. Sensory afferents innervating the aortic arch employ baroreceptors to convert stretch exerted on the arterial wall into action potentials carried by the vagus nerve to second order neurons residing within the nucleus of the solitary tract (NTS). Although the baroreflex was described more than 80 years ago, the specific molecular, structural, and functional phenotype of the baroreceptors remain uncharacterized. This is due to the lack of tools that provide the genetic and target organ specificity that is required to selectively characterize baroreceptor afferents. Here, we use a novel approach to selectively target baroreceptors. Male mice on a C57BL/6J background were anesthetized with isoflurane, intubated, and artificially ventilated. Following sternotomy, the aortic arch was exposed, and a retrograde adeno-associated virus was applied to the aortic arch to direct the expression of channelrhoropsin-2 (ChR2) and/or tdTomato (tdTom) to sensory afferents presumably functioning as baroreceptors. Consistent with the structural characteristics of arterial baroreceptors, robust tdTom expression was observed in nerve endings surrounding the aortic arch, within the fibers of the aortic depressor and vagus nerves, cell bodies of the nodose ganglia (NDG), and neural projections to the caudal NTS (cNTS). Additionally, the tdTom labeled cell bodies within the NDG also expressed mRNAs coding for the mechanically gated ion channels, PIEZO-1 and PIEZO-2. In vitro electrophysiology revealed that pulses of blue light evoked excitatory post-synaptic currents in a subset of neurons within the cNTS, suggesting a functional connection between the labeled aortic arch sensory afferents and second order neurons. Finally, the in vivo optogenetic stimulation of the cell bodies of the baroreceptor expressing afferents in the NDG produced robust depressor responses. Together, these results establish a novel approach for selectively targeting sensory neurons innervating the aortic arch. This approach may be used to investigate arterial baroreceptors structurally and functionally, and to assess their role in the etiology or reversal of cardiovascular disease., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Elsaafien, Harden, Johnson, Kimball, Sheng, Smith, Scott, Frazier, de Kloet and Krause.)
- Published
- 2022
- Full Text
- View/download PDF
13. Targeting angiotensin type-2 receptors located on pressor neurons in the nucleus of the solitary tract to relieve hypertension in mice.
- Author
-
Mohammed M, Johnson DN, Wang LA, Harden SW, Sheng W, Spector EA, Elsaafien K, Bader M, Steckelings UM, Scott KA, Frazier CJ, Sumners C, Krause EG, and de Kloet AD
- Subjects
- Animals, Imidazoles, Mice, Neurons metabolism, Sulfonamides, Thiophenes, Hypertension genetics, Hypertension metabolism, Receptor, Angiotensin, Type 2 metabolism, Solitary Nucleus metabolism
- Abstract
Aims: These studies evaluate whether angiotensin type-2 receptors (AT2Rs) that are expressed on γ-aminobutyric acid (GABA) neurons in the nucleus of the solitary tract (NTS) represent a novel endogenous blood pressure-lowering mechanism., Methods and Results: Experiments combined advanced genetic and neuroanatomical techniques, pharmacology, electrophysiology, and optogenetics in mice to define the structure and cardiovascular-related function of NTS neurons that contain AT2R. Using mice with Cre-recombinase directed to the AT2R gene, we discovered that optogenetic stimulation of AT2R-expressing neurons in the NTS increases GABA release and blood pressure. To evaluate the role of the receptor, per se, in cardiovascular regulation, we chronically delivered C21, a selective AT2R agonist, into the brains of normotensive mice and found that central AT2R activation reduces GABA-related gene expression and blunts the pressor responses induced by optogenetic excitation of NTS AT2R neurons. Next, using in situ hybridization, we found that the levels of Agtr2 mRNAs in GABAergic NTS neurons rise during experimentally induced hypertension, and we hypothesized that this increased expression may be exploited to ameliorate the disease. Consistent with this, final experiments revealed that central administration of C21 attenuates hypertension, an effect that is abolished in mice lacking AT2R in GABAergic NTS neurons., Conclusion: These studies unveil novel hindbrain circuits that maintain arterial blood pressure, and reveal a specific population of AT2R that can be engaged to alleviate hypertension. The implication is that these discrete receptors may serve as an access point for activating an endogenous depressor circuit., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)
- Published
- 2022
- Full Text
- View/download PDF
14. Identification and three-dimensional reconstruction of oxytocin receptor expressing astrocytes in the rat and mouse brain.
- Author
-
Althammer F, Krause EG, de Kloet AD, Smith J, Grinevich V, Charlet A, and Stern JE
- Subjects
- Animals, Imaging, Three-Dimensional methods, Immunohistochemistry, Mice, Rats, Receptors, Oxytocin genetics, Astrocytes, Central Amygdaloid Nucleus
- Abstract
Here, we present a step-by-step protocol for three-dimensional reconstruction of astrocyte morphology, applied to the central amygdala oxytocin receptor-expressing astrocytes. This includes RNAse-free perfusion, combination of RNAscope and immunohistochemistry, and confocal imaging. This protocol provides detailed information about tissue handling and a comprehensive description of the RNAScope technique to label rat and mouse oxytocin receptor mRNA. We also describe three-dimensional reconstruction that allows the assessment of more than 70 different cellular parameters, powerful for studying astrocyte morphology and astrocyte-astrocyte interactions. For complete details on the use and execution of this protocol, please refer to Wahis et al. (2021) and Althammer et al. (2020)., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors.)
- Published
- 2022
- Full Text
- View/download PDF
15. Conditioned social preference and reward value of activating oxytocin-receptor-expressing ventral tegmental area neurons following repeated daily binge ethanol intake.
- Author
-
Peris J, Totten K, Montgomery D, Lester H, Weatherington A, Piotrowski B, Sowell S, Doyle K, Scott K, Tan Y, MacFadyen KA, Engle H, de Kloet AD, and Krause EG
- Subjects
- Animals, Female, Humans, Male, Mice, Reward, Sex Factors, Ventral Tegmental Area drug effects, Binge Drinking psychology, Ethanol pharmacology, Oxytocin metabolism, Social Behavior Disorders
- Abstract
Background: Individuals with alcohol use disorder (AUD) exhibit a disruption of social behavior and dysregulation of oxytocin signaling in the brain, possibly reflecting decreased activation of oxytocin receptors (OxTRs) in reward pathways in response to social stimuli. We hypothesize that daily binge ethanol intake causes a deficit in social reward and oxytocin signaling in the ventral tegmental area (VTA)., Methods: After 9 weeks of daily binge ethanol intake (blood ethanol concentration >80 mg%), OxTR-cre mice underwent conditioned place preference for social reward. Separate groups of mice were tested for the effects of binge ethanol on voluntary social interactions, food reward, locomotion, and anxiety-like behaviors. A subset of mice underwent transfection of OxTR-expressing VTA neurons (VTA
Oxtr ) with a light-sensitive opsin, followed by operant training to respond to light delivered to VTA., Results: Ethanol-naïve male mice increased the time spent on the side previously paired with novel mice while ethanol-treated mice did not. Binge ethanol did not affect conditioned place preference for food reward in males, but this response was weakened in ethanol-treated females. Ethanol treatment also caused a sex-specific impairment of voluntary social interactions with novel mice. There were minimal differences between groups in measures of anxiety and locomotion. Ethanol-naïve mice had significantly greater operant responding for activation of VTAOxtr than sham-transfected mice but ethanol-treated mice did not. There was no difference in the number of VTAOxtr after binge ethanol., Conclusions: Daily binge ethanol causes social reward deficits that cannot be explained by nonspecific effects on other behaviors, at least in males. Only ethanol-naïve mice exhibited positive reinforcement caused by activation of VTAOxtr while daily binge ethanol did not alter the number of VTAOxtr in either males or females. Thus, subtle dysregulation of VTAOxtr function may be related to the social reward deficits caused by daily binge ethanol., (© 2022 by the Research Society on Alcoholism.)- Published
- 2022
- Full Text
- View/download PDF
16. Fecal matter transplant from Ace2 overexpressing mice counteracts chronic hypoxia-induced pulmonary hypertension.
- Author
-
Oliveira AC, Yang T, Li J, Sharma RK, Karas MK, Bryant AJ, de Kloet AD, Krause EG, Joe B, Richards EM, and Raizada MK
- Abstract
Recent evidence suggests pulmonary hypertension (PH), a disease of the pulmonary vasculature actually has multiorgan pathophysiology and perhaps etiology. Herein, we demonstrated that fecal matter transplantation from angiotensin-converting enzyme 2 overexpressing mice counteracted the effects of chronic hypoxia to prevent pulmonary hypertension, neuroinflammation, and gut dysbiosis in wild type recipients., Competing Interests: The authors declare that there are no conflict of interests., (© 2021 The Authors. Pulmonary Circulation published by Wiley Periodicals LLC on behalf of the Pulmonary Vascular Research Institute.)
- Published
- 2022
- Full Text
- View/download PDF
17. Dendritic osmosensors modulate activity-induced calcium influx in oxytocinergic magnocellular neurons of the mouse PVN.
- Author
-
Sheng W, Harden SW, Tan Y, Krause EG, and Frazier CJ
- Subjects
- Action Potentials, Animals, Electric Impedance, Female, Genes, Reporter, Luminescent Proteins genetics, Luminescent Proteins metabolism, Male, Mice, Transgenic, Microscopy, Fluorescence, Multiphoton, Paraventricular Hypothalamic Nucleus cytology, Receptors, GABA-A metabolism, Time Factors, Red Fluorescent Protein, Calcium Signaling, Dendrites metabolism, Osmoregulation, Oxytocin metabolism, Paraventricular Hypothalamic Nucleus metabolism
- Abstract
Hypothalamic oxytocinergic magnocellular neurons have a fascinating ability to release peptide from both their axon terminals and from their dendrites. Existing data indicates that the relationship between somatic activity and dendritic release is not constant, but the mechanisms through which this relationship can be modulated are not completely understood. Here, we use a combination of electrical and optical recording techniques to quantify activity-induced calcium influx in proximal vs. distal dendrites of oxytocinergic magnocellular neurons located in the paraventricular nucleus of the hypothalamus (OT-MCNs). Results reveal that the dendrites of OT-MCNs are weak conductors of somatic voltage changes; however, activity-induced dendritic calcium influx can be robustly regulated by both osmosensitive and non-osmosensitive ion channels located along the dendritic membrane. Overall, this study reveals that dendritic conductivity is a dynamic and endogenously regulated feature of OT-MCNs that is likely to have substantial functional impact on central oxytocin release., Competing Interests: WS, SH, YT, EK, CF No competing interests declared, (© 2021, Sheng et al.)
- Published
- 2021
- Full Text
- View/download PDF
18. Identification of Novel Cross-Talk between the Neuroendocrine and Autonomic Stress Axes Controlling Blood Pressure.
- Author
-
Elsaafien K, Kirchner MK, Mohammed M, Eikenberry SA, West C, Scott KA, de Kloet AD, Stern JE, and Krause EG
- Subjects
- Animals, Autonomic Nervous System physiology, Male, Mice, Neurons physiology, Blood Pressure physiology, Hypothalamo-Hypophyseal System physiology, Paraventricular Hypothalamic Nucleus physiology, Pituitary-Adrenal System physiology, Vasoconstriction physiology
- Abstract
The hypothalamic paraventricular nucleus (PVN) controls neuroendocrine axes and the autonomic nervous system to mount responses that cope with the energetic burdens of psychological or physiological stress. Neurons in the PVN that express the angiotensin Type 1a receptor (PVN
Agtr1a ) are implicated in neuroendocrine and autonomic stress responses; however, the mechanism by which these neurons coordinate activation of neuroendocrine axes with sympathetic outflow remains unknown. Here, we use a multidisciplinary approach to investigate intra-PVN signaling mechanisms that couple the activity of neurons synthesizing corticotropin-releasing-hormone (CRH) to blood pressure. We used the Cre-Lox system in male mice with in vivo optogenetics and cardiovascular recordings to demonstrate that excitation of PVNAgtr1a promotes elevated blood pressure that is dependent on the sympathetic nervous system. Next, neuroanatomical experiments found that PVNAgtr1a synthesize CRH, and intriguingly, fibers originating from PVNAgtr1a make appositions onto neighboring neurons that send projections to the rostral ventrolateral medulla and express CRH type 1 receptor (CRHR1) mRNA. We then used an ex vivo preparation that combined optogenetics, patch-clamp electrophysiology, and Ca2+ imaging to discover that excitation of PVNAgtr1a drives the local, intra-PVN release of CRH, which activates rostral ventrolateral medulla-projecting neurons via stimulation of CRHR1(s). Finally, we returned to our in vivo preparation and found that CRH receptor antagonism specifically within the PVN lowered blood pressure basally and during optogenetic activation of PVNAgtr1a Collectively, these results demonstrate that angiotensin II acts on PVNAgtr1a to conjoin hypothalamic-pituitary-adrenal axis activity with sympathetically mediated vasoconstriction in male mice. SIGNIFICANCE STATEMENT The survival of an organism is dependent on meeting the energetic demands imposed by stressors. This critical function is accomplished by the CNS's ability to orchestrate simultaneous activities of neurosecretory and autonomic axes. Here, we unveil a novel signaling mechanism within the paraventricular nucleus of the hypothalamus that links excitation of neurons producing corticotropin-releasing-hormone with excitation of neurons controlling sympathetic nervous system activity and blood pressure. The implication is that chronic stress exposure may promote cardiometabolic disease by dysregulating the interneuronal cross-talk revealed by our experiments., (Copyright © 2021 the authors.)- Published
- 2021
- Full Text
- View/download PDF
19. An Angiotensin-Responsive Connection from the Lamina Terminalis to the Paraventricular Nucleus of the Hypothalamus Evokes Vasopressin Secretion to Increase Blood Pressure in Mice.
- Author
-
Frazier CJ, Harden SW, Alleyne AR, Mohammed M, Sheng W, Smith JA, Elsaafien K, Spector EA, Johnson DN, Scott KA, Krause EG, and de Kloet AD
- Subjects
- Animals, Basal Nucleus of Meynert drug effects, Basal Nucleus of Meynert metabolism, Drinking drug effects, Genes, fos drug effects, Glutamic Acid physiology, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Optogenetics, Receptor, Angiotensin, Type 1 drug effects, Receptors, Vasopressin drug effects, Sodium, Dietary, Angiotensins pharmacology, Arginine Vasopressin metabolism, Blood Pressure drug effects, Hypothalamus drug effects, Neural Pathways drug effects, Paraventricular Hypothalamic Nucleus drug effects, Vasoconstrictor Agents pharmacology
- Abstract
Blood pressure is controlled by endocrine, autonomic, and behavioral responses that maintain blood volume and perfusion pressure at levels optimal for survival. Although it is clear that central angiotensin type 1a receptors (AT1aR; encoded by the Agtr1a gene) influence these processes, the neuronal circuits mediating these effects are incompletely understood. The present studies characterize the structure and function of AT1aR neurons in the lamina terminalis (containing the median preoptic nucleus and organum vasculosum of the lamina terminalis), thereby evaluating their roles in blood pressure control. Using male Agtr1a -Cre mice, neuroanatomical studies reveal that AT1aR neurons in the area are largely glutamatergic and send projections to the paraventricular nucleus of the hypothalamus (PVN) that appear to synapse onto vasopressin-synthesizing neurons. To evaluate the functionality of these lamina terminalis AT1aR neurons, we virally delivered light-sensitive opsins and then optogenetically excited or inhibited the neurons while evaluating cardiovascular parameters or fluid intake. Optogenetic excitation robustly elevated blood pressure, water intake, and sodium intake, while optogenetic inhibition produced the opposite effects. Intriguingly, optogenetic excitation of these AT1aR neurons of the lamina terminalis also resulted in Fos induction in vasopressin neurons within the PVN and supraoptic nucleus. Further, within the PVN, selective optogenetic stimulation of afferents that arise from these lamina terminalis AT1aR neurons induced glutamate release onto magnocellular neurons and was sufficient to increase blood pressure. These cardiovascular effects were attenuated by systemic pretreatment with a vasopressin-1a-receptor antagonist. Collectively, these data indicate that excitation of lamina terminalis AT1aR neurons induces neuroendocrine and behavioral responses that increase blood pressure. SIGNIFICANCE STATEMENT Hypertension is a widespread health problem and risk factor for cardiovascular disease. Although treatments exist, a substantial percentage of patients suffer from "drug-resistant" hypertension, a condition associated with increased activation of brain angiotensin receptors, enhanced sympathetic nervous system activity, and elevated vasopressin levels. The present study highlights a role for angiotensin Type 1a receptor expressing neurons located within the lamina terminalis in regulating endocrine and behavioral responses that are involved in maintaining cardiovascular homeostasis. More specifically, data presented here reveal functional excitatory connections between angiotensin-sensitive neurons in the lamina terminals and vasopressin neurons in the paraventricular nucleus of the hypothalamus, and further indicate that activation of this circuit raises blood pressure. These neurons may be a promising target for antihypertensive therapeutics., (Copyright © 2021 the authors.)
- Published
- 2021
- Full Text
- View/download PDF
20. Overexpression of angiotensin converting enzyme 2 reduces anxiety-like behavior in female mice.
- Author
-
de Kloet AD, Cahill KM, Scott KA, and Krause EG
- Subjects
- Angiotensin II, Angiotensin-Converting Enzyme 2, Animals, Anxiety, Female, Male, Mice, Mice, Knockout, Peptide Fragments metabolism, Pituitary-Adrenal System metabolism, Renin-Angiotensin System genetics, Hypothalamo-Hypophyseal System metabolism, Peptidyl-Dipeptidase A genetics, Peptidyl-Dipeptidase A metabolism
- Abstract
Accumulating evidence has revealed an intricate role for the renin-angiotensin system (RAS) in the progression or alleviation of stress-related disorders. Along these lines, the 'pro-stress' actions of angiotensin-II (Ang-II) are largely thought to be mediated by the angiotensin type-1a receptor (AT1aR). On the other hand, a counter regulatory limb of the RAS that depends on the conversion of Ang-II to angiotensin-(1-7) by angiotensin-converting enzyme 2 (ACE2) has been postulated to exert stress-dampening actions. We have previously found that augmenting ACE2 activity is potently anxiolytic and blunts stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis in male mice. Whether increasing ACE2 activity also relieves stress and anxiety in females has not yet been determined. Consequently, this series of experiments tests the hypothesis that augmenting ACE2 expression is anxiolytic and dampens the activity of the HPA axis in female mice. Using the Cre-LoxP system, we generated female mice that were homo-, heterozygous or wild-type for a mutated allele resulting in ubiquitous overexpression of ACE2. Next, we used qPCR to determine that levels of ACE2 mRNA isolated from central and peripheral tissues was dependent on genotype. That is, mice homo- and heterozygous for the ACE2 overexpression had significantly greater levels of ACE2 mRNA relative to littermate matched wild-type controls. Interestingly, anxiety-like behavior as determined by the elevated plus maze, light-dark box and novelty-induced hypophagia tests was also affected by genotype. Specifically, ACE2 overexpression significantly decreased anxiety-like behavior in paradigms dependent on approach-avoidance conflict and novelty; however, locomotor activity was similar amongst the genotypes. Final experiments measured plasma corticosterone to evaluate whether increasing ACE2 alters basal and/or stress-induced HPA axis activity. In contrast to what was previously found in males, increasing ACE2 expression had no effect on plasma corticosterone under basal conditions or subsequent to an acute restraint challenge. Collectively, these results suggest that increasing ACE2 expression potently elicits anxiolysis in female mice without altering HPA axis activity., (Copyright © 2020. Published by Elsevier Inc.)
- Published
- 2020
- Full Text
- View/download PDF
21. Brain Angiotensin Type-1 and Type-2 Receptors in Physiological and Hypertensive Conditions: Focus on Neuroinflammation.
- Author
-
Elsaafien K, de Kloet AD, Krause EG, and Sumners C
- Subjects
- Angiotensin I, Brain metabolism, Humans, Receptor, Angiotensin, Type 1 metabolism, Receptors, Angiotensin, Hypertension, Receptor, Angiotensin, Type 2 metabolism
- Abstract
Purpose of Review: To review recent data that suggest opposing effects of brain angiotensin type-1 (AT
1 R) and type-2 (AT2 R) receptors on blood pressure (BP). Here, we discuss recent studies that suggest pro-hypertensive and pro-inflammatory actions of AT1 R and anti-hypertensive and anti-inflammatory actions of AT2 R. Further, we propose mechanisms for the interplay between brain angiotensin receptors and neuroinflammation in hypertension., Recent Findings: The renin-angiotensin system (RAS) plays an important role in regulating cardiovascular physiology. This includes brain AT1 R and AT2 R, both of which are expressed in or adjacent to brain regions that control BP. Activation of AT1 R within those brain regions mediate increases in BP and cause neuroinflammation, which augments the BP increase in hypertension. The fact that AT1 R and AT2 R have opposing actions on BP suggests that AT1 R and AT2 R may have similar opposing actions on neuroinflammation. However, the mechanisms by which brain AT1 R and AT2 R mediate neuroinflammatory responses remain unclear. The interplay between brain angiotensin receptor subtypes and neuroinflammation exacerbates or protects against hypertension.- Published
- 2020
- Full Text
- View/download PDF
22. Gut Pathology and Its Rescue by ACE2 (Angiotensin-Converting Enzyme 2) in Hypoxia-Induced Pulmonary Hypertension.
- Author
-
Sharma RK, Oliveira AC, Yang T, Karas MM, Li J, Lobaton GO, Aquino VP, Robles-Vera I, de Kloet AD, Krause EG, Bryant AJ, Verma A, Li Q, Richards EM, and Raizada MK
- Subjects
- Angiotensin-Converting Enzyme 2 genetics, Animals, Dysbiosis enzymology, Dysbiosis microbiology, Dysbiosis therapy, Fecal Microbiota Transplantation, Gene Knock-In Techniques, Hemodynamics, Hypertension, Pulmonary enzymology, Hypertension, Pulmonary etiology, Hypertension, Pulmonary prevention & control, Hypertrophy, Right Ventricular etiology, Hypertrophy, Right Ventricular prevention & control, Hypoxia microbiology, Inflammation, Lung enzymology, Lung physiopathology, Mice, Microglia pathology, Paraventricular Hypothalamic Nucleus pathology, Sympathetic Nervous System physiopathology, Angiotensin-Converting Enzyme 2 physiology, Dysbiosis etiology, Gastrointestinal Microbiome, Hypertension, Pulmonary microbiology, Hypoxia complications
- Abstract
Therapeutic advances for pulmonary hypertension (PH) have been incremental because of the focus on the pulmonary vasculature in PH pathology. Here, we evaluate the concept that PH is, rather, a systemic disorder involving interplay among multiorgan systems, including brain, gut, and lungs. Therefore, the objective of this study was to evaluate the hypothesis that PH is associated with a dysfunctional brain-gut-lung axis and that global overexpression of ACE2 (angiotensin-converting enzyme 2) rebalances this axis and protects against PH. ACE2 knockin and wild-type (WT; C57BL/6) mice were subjected to chronic hypoxia (10% FIO2) or room air for 4 weeks. Cardiopulmonary hemodynamics, histology, immunohistochemistry, and fecal 16S rRNA microbial gene analyses were evaluated. Hypoxia significantly increased right ventricular systolic pressure, sympathetic activity as well as the number and activation of microglia in the paraventricular nucleus of the hypothalamus in WT mice. This was associated with a significant increase in muscularis layer thickening and decreases in both villi length and goblet cells and altered gut microbiota. Global overexpression of ACE2 prevented changes in hypoxia-induced pulmonary and gut pathophysiology and established distinct microbial communities from WT hypoxia mice. Furthermore, WT mice subjected to fecal matter transfer from ACE2 knockin mice were resistant to hypoxia-induced PH compared with their controls receiving WT fecal matter transfer. These observations demonstrate that ACE2 ameliorates these hypoxia-induced pathologies and attenuates PH. The data implicate dysfunctional brain-gut-lung communication in PH and provide novel avenues for therapeutic interventions.
- Published
- 2020
- Full Text
- View/download PDF
23. Oxytocin treatment for alcoholism: Potential neurocircuitry targets.
- Author
-
Peris J, Steck MR, and Krause EG
- Subjects
- Alcoholism physiopathology, Animals, Dopaminergic Neurons drug effects, Humans, Nerve Net physiopathology, Signal Transduction drug effects, Alcoholism drug therapy, Nerve Net drug effects, Oxytocin therapeutic use
- Abstract
Oxytocin (OT) has gained considerable interest in recent years as a potential treatment for alcoholism and other substance use disorders. Evidence continues to mount that OT administered either centrally, peripherally or intranasally can decrease ethanol intake in both humans and animal models. The potential mechanisms for the ability of OT to decrease ethanol reward, and importantly, cue- and stress-induced ethanol relapse, are explored by reviewing the specific neuronal circuits involved in mediating these actions and their sensitivity to OT. In addition to dopamine neurons that project from ventral tegmental area (VTA) to nucleus accumbens (NAc) to signal positively reinforcing events, OT receptors (OxTR) are also expressed by dopamine neurons that project from VTA to brain regions that can convey aversive properties of a stimulus. Moreover, OxTR are expressed by non-dopaminergic neurons in the VTA, such as GABA and glutamate neurons, which can both modulate the activity of dopamine VTA neurons locally (in opposite directions) or can project to other brain regions, including the NAc, where it can alter either positive reinforcement or aversion caused by ethanol. The ability of OT to regulate limbic circuitry and the hypothalamic-pituitary-adrenal axis is discussed as a potential mechanism for the ability of OT to inhibit ethanol-induced negative reinforcement. Together, understanding the diversity and complexity of OT regulation of ethanol reward may contribute to more effective use of OT as pharmacotherapy for alcohol use disorder. This article is part of the special issue on Neuropeptides., (Copyright © 2020 Elsevier Ltd. All rights reserved.)
- Published
- 2020
- Full Text
- View/download PDF
24. Brain angiotensin type-1 and type-2 receptors: cellular locations under normal and hypertensive conditions.
- Author
-
Sumners C, Alleyne A, Rodríguez V, Pioquinto DJ, Ludin JA, Kar S, Winder Z, Ortiz Y, Liu M, Krause EG, and de Kloet AD
- Subjects
- Animals, Blood Pressure physiology, Mice, Rats, Rats, Inbred SHR, Rats, Sprague-Dawley, Rats, Wistar, Astrocytes metabolism, Brain metabolism, Hypertension metabolism, Microglia metabolism, Neurons metabolism, Receptor, Angiotensin, Type 1 metabolism, Receptor, Angiotensin, Type 2 metabolism
- Abstract
Brain angiotensin-II (Ang-II) type-1 receptors (AT1Rs), which exert profound effects on normal cardiovascular, fluid, and metabolic homeostasis, are overactivated in and contribute to chronic sympathoexcitation and hypertension. Accumulating evidence indicates that the activation of Ang-II type-2 receptors (AT2Rs) in the brain exerts effects that are opposite to those of AT1Rs, lowering blood pressure, and reducing hypertension. Thus, it would be interesting to understand the relative cellular localization of AT1R and AT2R in the brain under normal conditions and whether this localization changes during hypertension. Here, we developed a novel AT1aR-tdTomato reporter mouse strain in which the location of brain AT1aR was largely consistent with that determined in the previous studies. This AT1aR-tdTomato reporter mouse strain was crossed with our previously described AT2R-eGFP reporter mouse strain to yield a novel dual AT1aR/AT2R reporter mouse strain, which allowed us to determine that AT1aR and AT2R are primarily localized to different populations of neurons in brain regions controlling cardiovascular, fluid, and metabolic homeostasis. Using the individual AT1aR-tdTomato reporter mice, we also demonstrated that during hypertension induced by the administration of deoxycorticosterone acetate-salt, there was no shift in the expression of AT1aR from neurons to microglia or astrocytes in the paraventricular nucleus, a brain area important for sympathetic regulation. Using AT2R-eGFP reporter mice under similar hypertensive conditions, we demonstrated that the same was true of AT2R expression in the nucleus of the solitary tract (NTS), an area critical for baroreflex control. Collectively, these findings provided a novel means to assess the colocalization of AT1R and AT2R in the brain and a novel view of their cellular localization in hypertension.
- Published
- 2020
- Full Text
- View/download PDF
25. Endogenous oxytocin inhibits hypothalamic corticotrophin-releasing hormone neurones following acute hypernatraemia.
- Author
-
Pati D, Harden SW, Sheng W, Kelly KB, de Kloet AD, Krause EG, and Frazier CJ
- Subjects
- Animals, Hypothalamo-Hypophyseal System metabolism, Male, Mice, Mice, Knockout, Mice, Transgenic, Pituitary-Adrenal System metabolism, Receptors, Oxytocin genetics, Receptors, Oxytocin metabolism, Corticotropin-Releasing Hormone metabolism, Hypernatremia metabolism, Hypothalamus metabolism, Neurons metabolism, Oxytocin metabolism
- Abstract
Significant prior evidence indicates that centrally acting oxytocin robustly modulates stress responsiveness and anxiety-like behaviour, although the neural mechanisms behind these effects are not entirely understood. A plausible neural basis for oxytocin-mediated stress reduction is via inhibition of corticotrophin-releasing hormone (CRH) neurones in the paraventricular nucleus of the hypothalamus (PVN) that regulate activation of the hypothalamic-pituitary-adrenal axis. Previously, we have shown that, following s.c. injection of 2.0 mol L
-1 NaCl, oxytocin synthesising neurones are activated in the rat PVN, an oxytocin receptor (Oxtr)-dependent inhibitory tone develops on a subset of parvocellular neurones and stress-mediated increases in plasma corticosterone levels are blunted. In the present study, we utilised transgenic male CRH-reporter mice to selectively target PVN CRH neurones for whole-cell recordings. These experiments reveal that acute salt loading produces tonic inhibition of PVN CRH neurones through a mechanism that is largely independent of synaptic activity. Further studies reveal that a subset of CRH neurones within the PVN synthesise mRNA for Oxtr(s). Salt induced Oxtr-dependent inhibitory tone was eliminated in individual PVN CRH neurones filled with GDP-β-S. Additional electrophysiological studies suggest that reduced excitability of PVN CRH neurones in salt-loaded animals is associated with increased activation of inwardly rectifying potassium channels. Nevertheless, substantial effort to recapitulate the core effects of salt loading by activating Oxtr(s) with an exogenous agonist produced mixed results. Collectively, these results enhance our understanding of how oxytocin receptor-mediated signalling modulates the function of CRH neurones in the PVN., (© 2020 British Society for Neuroendocrinology.)- Published
- 2020
- Full Text
- View/download PDF
26. An anti-CRF antibody suppresses the HPA axis and reverses stress-induced phenotypes.
- Author
-
Futch HS, McFarland KN, Moore BD, Kuhn MZ, Giasson BI, Ladd TB, Scott KA, Shapiro MR, Nosacka RL, Goodwin MS, Ran Y, Cruz PE, Ryu DH, Croft CL, Levites Y, Janus C, Chakrabarty P, Judge AR, Brusko TM, de Kloet AD, Krause EG, and Golde TE
- Subjects
- Animals, Antibodies, Monoclonal immunology, Cell Line, Tumor, Corticosterone immunology, Corticosterone metabolism, Corticotropin-Releasing Hormone immunology, Gene Expression Profiling methods, Humans, Hypothalamo-Hypophyseal System immunology, Hypothalamo-Hypophyseal System metabolism, Mice, Inbred BALB C, Mice, Inbred C57BL, Phenotype, Pituitary-Adrenal System immunology, Pituitary-Adrenal System metabolism, Signal Transduction drug effects, Signal Transduction genetics, Stress, Physiological immunology, Antibodies, Monoclonal pharmacology, Corticotropin-Releasing Hormone antagonists & inhibitors, Hypothalamo-Hypophyseal System drug effects, Pituitary-Adrenal System drug effects, Stress, Physiological drug effects
- Abstract
Hypothalamic-pituitary-adrenal (HPA) axis dysfunction contributes to numerous human diseases and disorders. We developed a high-affinity monoclonal antibody, CTRND05, targeting corticotropin-releasing factor (CRF). In mice, CTRND05 blocks stress-induced corticosterone increases, counteracts effects of chronic variable stress, and induces other phenotypes consistent with suppression of the HPA axis. CTRND05 induces skeletal muscle hypertrophy and increases lean body mass, effects not previously reported with small-molecule HPA-targeting pharmacologic agents. Multiorgan transcriptomics demonstrates broad HPA axis target engagement through altering levels of known HPA-responsive transcripts such as Fkbp5 and Myostatin and reveals novel HPA-responsive pathways such as the Apelin-Apelin receptor system. These studies demonstrate the therapeutic potential of CTRND05 as a suppressor of the HPA axis and serve as an exemplar of a potentially broader approach to target neuropeptides with immunotherapies, as both pharmacologic tools and novel therapeutics., (© 2019 Futch et al.)
- Published
- 2019
- Full Text
- View/download PDF
27. Oxytocin Receptors Are Expressed by Glutamatergic Prefrontal Cortical Neurons That Selectively Modulate Social Recognition.
- Author
-
Tan Y, Singhal SM, Harden SW, Cahill KM, Nguyen DM, Colon-Perez LM, Sahagian TJ, Thinschmidt JS, de Kloet AD, Febo M, Frazier CJ, and Krause EG
- Subjects
- Animals, Male, Mice, Mice, Transgenic, Optogenetics, Receptors, Oxytocin genetics, Glutamic Acid metabolism, Neurons metabolism, Prefrontal Cortex metabolism, Receptors, Oxytocin metabolism, Recognition, Psychology physiology, Social Behavior
- Abstract
Social recognition, the ability to recognize individuals that were previously encountered, requires complex integration of sensory inputs with previous experience. Here, we use a variety of approaches to discern how oxytocin-sensitive neurons in the PFC exert descending control over a circuit mediating social recognition in mice. Using male mice with Cre-recombinase directed to the oxytocin receptor gene ( Oxtr ), we revealed that oxytocin receptors (OXTRs) are expressed on glutamatergic neurons in the PFC, optogenetic stimulation of which elicited activation of neurons residing in several mesolimbic brain structures. Optogenetic stimulation of axons in the BLA arising from OXTR-expressing neurons in the PFC eliminated the ability to distinguish novel from familiar conspecifics, but remarkably, distinguishing between novel and familiar objects was unaffected. These results suggest that an oxytocin-sensitive PFC to BLA circuit is required for social recognition. The implication is that impaired social memory may manifest from dysregulation of this circuit. SIGNIFICANCE STATEMENT Using mice, we demonstrate that optogenetic activation of the neurons in the PFC that express the oxytocin receptor gene ( Oxtr ) impairs the ability to distinguish between novel and familiar conspecifics, but the ability to distinguish between novel and familiar objects remains intact. Subjects with autism spectrum disorders (ASDs) have difficulty identifying a person based on remembering facial features; however, ASDs and typical subjects perform similarly when remembering objects. In subjects with ASD, viewing the same face increases neural activity in the PFC, which may be analogous to the optogenetic excitation of oxytocin receptor (OXTR) expressing neurons in the PFC that impairs social recognition in mice. The implication is that overactivation of OXTR-expressing neurons in the PFC may contribute to ASD symptomology., (Copyright © 2019 the authors.)
- Published
- 2019
- Full Text
- View/download PDF
28. Stress-induced corticosterone secretion covaries with working memory in aging.
- Author
-
McQuail JA, Krause EG, Setlow B, Scheuer DA, and Bizon JL
- Subjects
- Animals, Choice Behavior, Hypothalamo-Hypophyseal System metabolism, Male, Pituitary-Adrenal System metabolism, Prefrontal Cortex physiology, Rats, Inbred F344, Restraint, Physical, Aging, Corticosterone blood, Memory, Short-Term physiology, Stress, Psychological blood, Stress, Psychological psychology
- Abstract
A substantial literature details the relationship between age-related changes to the hypothalamic-pituitary-adrenal axis and deterioration of mnemonic functions that depend on the hippocampus. The relationship between adrenocortical status and other forms of memory that depend on the prefrontal cortex is less well understood in the context of advanced age. Here, we characterized performance of young adult and aged F344 rats on a prefrontal cortex-dependent working memory task and subsequently measured corticosterone (CORT) levels over the diurnal cycle and during exposure to an acute stressor. Our analyses revealed that aged rats with better working memory mounted a greater CORT response during acute stress exposure than either young adults or age-matched rats with impaired working memory. We also observed that age-related elevation of basal CORT levels is not associated with working memory performance. Jointly, these data reveal that the hypothalamic-pituitary-adrenal axis-mediated response to acute stress is positively associated with working memory in aging., (Copyright © 2018 Elsevier Inc. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
29. A novel rat model of comorbid PTSD and addiction reveals intersections between stress susceptibility and enhanced cocaine seeking with a role for mGlu5 receptors.
- Author
-
Schwendt M, Shallcross J, Hadad NA, Namba MD, Hiller H, Wu L, Krause EG, and Knackstedt LA
- Subjects
- Animals, Anxiety, Behavior, Animal, Brain drug effects, Brain metabolism, Cocaine administration & dosage, Cocaine-Related Disorders metabolism, Comorbidity, Extinction, Psychological drug effects, Fear, Male, Phenotype, Rats, Sprague-Dawley, Resilience, Psychological, Stress Disorders, Post-Traumatic metabolism, Stress, Psychological chemically induced, Stress, Psychological metabolism, Thiazoles administration & dosage, Cocaine-Related Disorders complications, Disease Models, Animal, Drug-Seeking Behavior, Receptor, Metabotropic Glutamate 5 metabolism, Stress Disorders, Post-Traumatic complications, Stress, Psychological complications
- Abstract
PTSD is highly comorbid with cocaine use disorder (CUD), and cocaine users with PTSD + CUD are more resistant to treatment. Here we sought to develop a rat model of PTSD + CUD in order to identify the neurobiological changes underlying such comorbidity and screen potential medications for reducing cocaine seeking in the PTSD population. We utilized a predator scent stress model of PTSD, wherein rats received a single exposure to the fox pheromone 2,5-dihydro-2,4,5-trimethylthiazoline (TMT). One week after TMT exposure, stress-susceptible (susceptible), intermediate, and resilient phenotypes were detected and were consistent with behavioral, corticosterone, and gene expression profiles 3 weeks post TMT. We assessed phenotypic differences in cocaine self-administration, extinction, and cue-primed reinstatement. Susceptible rats exhibited deficits in extinction learning and increased cue-primed reinstatement that was not prevented by Ceftriaxone, an antibiotic that consistently attenuates the reinstatement of cocaine seeking. TMT-exposed resilient rats displayed increased mGlu5 gene expression in the amygdala and medial prefrontal cortex and did not display the enhanced cocaine seeking observed in susceptible rats. Combined treatment with the mGlu5 positive allosteric modulator 3-Cyano-N-(1,3-diphenyl-1 H-pyrazol-5-yl)benzamide (CDPPB), fear extinction, and ceftriaxone prevented the reinstatement of cocaine seeking in susceptible rats with fear extinction an important mediating condition. These results highlight the need for animal models of PTSD to consider stress-responsivity, as only a subset of trauma-exposed individuals develop PTSD and these individuals likely exhibit distinct neurobiological changes compared with trauma-exposed populations who are resilient to stress. This work further identifies glutamate homeostasis and mGlu5 as a target for treating relapse in comorbid PTSD-cocaine addiction.
- Published
- 2018
- Full Text
- View/download PDF
30. Macrophage angiotensin II type 2 receptor triggers neuropathic pain.
- Author
-
Shepherd AJ, Mickle AD, Golden JP, Mack MR, Halabi CM, de Kloet AD, Samineni VK, Kim BS, Krause EG, Gereau RW 4th, and Mohapatra DP
- Subjects
- Allografts, Animals, Chronic Pain genetics, Chronic Pain pathology, Hematopoietic Stem Cell Transplantation, Macrophages pathology, Mice, Neuralgia genetics, Neuralgia pathology, Receptor, Angiotensin, Type 2 genetics, Chronic Pain metabolism, Macrophages metabolism, Neuralgia metabolism, Receptor, Angiotensin, Type 2 metabolism
- Abstract
Peripheral nerve damage initiates a complex series of structural and cellular processes that culminate in chronic neuropathic pain. The recent success of a type 2 angiotensin II (Ang II) receptor (AT2R) antagonist in a phase II clinical trial for the treatment of postherpetic neuralgia suggests angiotensin signaling is involved in neuropathic pain. However, transcriptome analysis indicates a lack of AT2R gene ( Agtr2 ) expression in human and rodent sensory ganglia, raising questions regarding the tissue/cell target underlying the analgesic effect of AT2R antagonism. We show that selective antagonism of AT2R attenuates neuropathic but not inflammatory mechanical and cold pain hypersensitivity behaviors in mice. Agtr2 -expressing macrophages (MΦs) constitute the predominant immune cells that infiltrate the site of nerve injury. Interestingly, neuropathic mechanical and cold pain hypersensitivity can be attenuated by chemogenetic depletion of peripheral MΦs and AT2R-null hematopoietic cell transplantation. Our study identifies AT2R on peripheral MΦs as a critical trigger for pain sensitization at the site of nerve injury, and therefore proposes a translatable peripheral mechanism underlying chronic neuropathic pain., Competing Interests: The authors declare no conflict of interest.
- Published
- 2018
- Full Text
- View/download PDF
31. Angiotensin II Triggers Peripheral Macrophage-to-Sensory Neuron Redox Crosstalk to Elicit Pain.
- Author
-
Shepherd AJ, Copits BA, Mickle AD, Karlsson P, Kadunganattil S, Haroutounian S, Tadinada SM, de Kloet AD, Valtcheva MV, McIlvried LA, Sheahan TD, Jain S, Ray PR, Usachev YM, Dussor G, Krause EG, Price TJ, Gereau RW 4th, and Mohapatra DP
- Subjects
- Angiotensin II toxicity, Angiotensin Receptor Antagonists pharmacology, Animals, Cell Communication physiology, Cells, Cultured, Female, Ganglia, Spinal cytology, Genes, Reporter, Humans, Hyperalgesia chemically induced, Hyperalgesia drug therapy, Imidazoles pharmacology, Macrophage Activation, Macrophages, Peritoneal drug effects, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Neuralgia drug therapy, Neutrophil Activation, Oxidation-Reduction, Pyridines pharmacology, Receptor, Angiotensin, Type 2 genetics, Sensory Receptor Cells chemistry, Skin cytology, TRPA1 Cation Channel deficiency, Tacrolimus analogs & derivatives, Tacrolimus pharmacology, Angiotensin II physiology, Hyperalgesia physiopathology, Macrophages, Peritoneal metabolism, Neuralgia physiopathology, Receptor, Angiotensin, Type 2 physiology, Sensory Receptor Cells physiology, TRPA1 Cation Channel physiology
- Abstract
Injury, inflammation, and nerve damage initiate a wide variety of cellular and molecular processes that culminate in hyperexcitation of sensory nerves, which underlies chronic inflammatory and neuropathic pain. Using behavioral readouts of pain hypersensitivity induced by angiotensin II (Ang II) injection into mouse hindpaws, our study shows that activation of the type 2 Ang II receptor (AT2R) and the cell-damage-sensing ion channel TRPA1 are required for peripheral mechanical pain sensitization induced by Ang II in male and female mice. However, we show that AT2R is not expressed in mouse and human dorsal root ganglia (DRG) sensory neurons. Instead, expression/activation of AT2R on peripheral/skin macrophages (MΦs) constitutes a critical trigger of mouse and human DRG sensory neuron excitation. Ang II-induced peripheral mechanical pain hypersensitivity can be attenuated by chemogenetic depletion of peripheral MΦs. Furthermore, AT2R activation in MΦs triggers production of reactive oxygen/nitrogen species, which trans -activate TRPA1 on mouse and human DRG sensory neurons via cysteine modification of the channel. Our study thus identifies a translatable immune cell-to-sensory neuron signaling crosstalk underlying peripheral nociceptor sensitization. This form of cell-to-cell signaling represents a critical peripheral mechanism for chronic pain and thus identifies multiple druggable analgesic targets. SIGNIFICANCE STATEMENT Pain is a widespread health problem that is undermanaged by currently available analgesics. Findings from a recent clinical trial on a type II angiotensin II receptor (AT2R) antagonist showed effective analgesia for neuropathic pain. AT2R antagonists have been shown to reduce neuropathy-, inflammation- and bone cancer-associated pain in rodents. We report that activation of AT2R in macrophages (MΦs) that infiltrate the site of injury, but not in sensory neurons, triggers an intercellular redox communication with sensory neurons via activation of the cell damage/pain-sensing ion channel TRPA1. This MΦ-to-sensory neuron crosstalk results in peripheral pain sensitization. Our findings provide an evidence-based mechanism underlying the analgesic action of AT2R antagonists, which could accelerate the development of efficacious non-opioid analgesic drugs for multiple pain conditions., (Copyright © 2018 the authors 0270-6474/18/387033-26$15.00/0.)
- Published
- 2018
- Full Text
- View/download PDF
32. Coupling corticotropin-releasing-hormone and angiotensin converting enzyme 2 dampens stress responsiveness in male mice.
- Author
-
Wang LA, de Kloet AD, Smeltzer MD, Cahill KM, Hiller H, Bruce EB, Pioquinto DJ, Ludin JA, Katovich MJ, Raizada MK, and Krause EG
- Subjects
- Adrenocorticotropic Hormone pharmacology, Angiotensin-Converting Enzyme 2, Animals, Anxiety drug therapy, Anxiety etiology, Corticotropin-Releasing Hormone blood, Corticotropin-Releasing Hormone genetics, Diminazene analogs & derivatives, Diminazene therapeutic use, Disease Models, Animal, Dose-Response Relationship, Drug, Enzyme Activators therapeutic use, Hormones pharmacology, Hypothalamo-Hypophyseal System drug effects, Hypothalamo-Hypophyseal System metabolism, Injections, Intraventricular, Male, Maze Learning drug effects, Mice, Mice, Inbred C57BL, Mice, Knockout, Peptidyl-Dipeptidase A genetics, Pituitary Gland metabolism, Pituitary-Adrenal System diagnostic imaging, Pituitary-Adrenal System metabolism, Pro-Opiomelanocortin genetics, Pro-Opiomelanocortin metabolism, RNA, Messenger metabolism, Stress, Psychological drug therapy, Stress, Psychological genetics, Corticotropin-Releasing Hormone metabolism, Corticotropin-Releasing Hormone therapeutic use, Peptidyl-Dipeptidase A metabolism, Stress, Psychological metabolism
- Abstract
This study used mice to evaluate whether coupling expression of corticotropin-releasing hormone (CRH) and angiotensin converting enzyme 2 (ACE2) creates central interactions that blunt endocrine and behavioral responses to psychogenic stress. Central administration of diminazene aceturate, an ACE2 activator, had no effect on restraint-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis; however, mice that ubiquitously overexpress ACE2 had reduced plasma corticosterone (CORT) and pituitary expression of POMC mRNA. The Cre-LoxP system was used to restrict ACE2 overexpression to CRH synthesizing cells and probe whether HPA axis suppression was the result of central ACE2 and CRH interactions. Within the paraventricular nucleus of the hypothalamus (PVN), mice with ACE2 overexpression directed to CRH had a ≈2.5 fold increase in ACE2 mRNA, which co-localized with CRH mRNA. Relative to controls, mice overexpressing ACE2 in CRH cells had a decreased CORT response to restraint as well as decreased CRH mRNA in the PVN and CEA and POMC mRNA in the pituitary. Administration of ACTH similarly increased plasma CORT, indicating that the blunted HPA axis activation that accompanies ACE2 overexpression in CRH cells is centrally mediated. Anxiety-like behavior was assessed to determine whether the decreased HPA axis activation was predictive of anxiolysis. Mice with ACE2 overexpression directed to CRH cells displayed decreased anxiety-like behavior in the elevated plus maze and open field when compared to that of controls. Collectively, these results suggest that exogenous ACE2 suppresses CRH synthesis, which alters the central processing of psychogenic stress, thereby blunting HPA axis activation and attenuating anxiety-like behavior., (Copyright © 2018 Elsevier Ltd. All rights reserved.)
- Published
- 2018
- Full Text
- View/download PDF
33. Ischemia-responsive protein 94 is a key mediator of ischemic neuronal injury-induced microglial activation.
- Author
-
Tikamdas R, Singhal S, Zhang P, Smith JA, Krause EG, Stevens SM Jr, Song S, and Liu B
- Abstract
Neuroinflammation, especially activation of microglia, the key immune cells in the brain, has been proposed to contribute to the pathogenesis of ischemic stroke. However, the dynamics and the potential mediators of microglial activation following ischemic neuronal injury are not well understood. In this study, using oxygen/glucose deprivation and reoxygenation with neuronal and microglial cell cultures as an in vitro model of ischemic neuronal injury, we set out to identify neuronal factors released from injured neurons that are capable of inducing microglial activation. Conditioned media (CM) from hippocampal and cortical neurons exposed to oxygen/glucose deprivation and reoxygenation induced significant activation of microglial cells as well as primary microglia, evidenced by up-regulation of inducible nitric oxide synthase, increased production of nitrite and reactive oxygen species, and increased expression of microglial markers. Mechanistically, neuronal ischemia-responsive protein 94 (Irp94) was a key contributor to microglial activation since significant increase in Irp94 was detected in the neuronal CM following ischemic insult and immunodepletion of Irp94 rendered ischemic neuronal CM ineffective in inducing microglial activation. Ischemic insult-augmented oxidative stress was a major facilitator of neuronal Irp94 release, and pharmacological inhibition of NADPH oxidase significantly reduced the ischemic injury-induced neuronal reactive oxygen species production and Irp94 release. Taken together, these results indicate that neuronal Irp94 may play a pivotal role in the propagation of ischemic neuronal damage. Continued studies may help identify Irp94 and/or related proteins as potential therapeutic targets and/or diagnostic/prognostic biomarkers for managing ischemia-associated brain disorders., (© 2017 International Society for Neurochemistry.)
- Published
- 2017
- Full Text
- View/download PDF
34. Susceptibility or resilience? Prenatal stress predisposes male rats to social subordination, but facilitates adaptation to subordinate status.
- Author
-
Scott KA, de Kloet AD, Smeltzer MD, Krause EG, Flak JN, Melhorn SJ, Foster MT, Tamashiro KLK, and Sakai RR
- Subjects
- Adrenal Glands pathology, Animals, Behavior, Animal physiology, Brain metabolism, Brain pathology, Corticosterone blood, Depression etiology, Female, Housing, Animal, Male, Organ Size, Pregnancy, Prenatal Exposure Delayed Effects pathology, Psychological Tests, RNA, Messenger metabolism, Rats, Long-Evans, Stress, Psychological complications, Stress, Psychological pathology, Testosterone blood, Thymus Gland pathology, Adaptation, Psychological, Dominance-Subordination, Prenatal Exposure Delayed Effects metabolism, Prenatal Exposure Delayed Effects psychology, Resilience, Psychological, Stress, Psychological metabolism
- Abstract
Mood disorders such as major depressive disorder (MDD) affect a significant proportion of the population. Although progress has been made in the development of therapeutics, a large number of individuals do not attain full remission of symptoms and adverse side effects affect treatment compliance for some. In order to develop new therapies, there is a push for new models that better reflect the multiple risk factors that likely contribute to the development of depressive illness. We hypothesized that early life stress would exacerbate the depressive-like phenotype that we have previously observed in socially subordinate (SUB) adult male rats in the visible burrow system (VBS), a semi-natural, ethologically relevant environment in which males in a colony form a dominance hierarchy. Dams were exposed to chronic variable stress (CVS) during the last week of gestation, resulting in a robust and non-habituating glucocorticoid response that did not alter maternal food intake, body weight or litter size and weight. As adults, one prenatal CVS (PCVS) and one non-stressed (NS) male were housed in the VBS with adult females. Although there were no overt differences between PCVS and NS male offspring prior to VBS housing, a greater percentage of PCVS males became SUB. However, the depressive-like phenotype of SUB males was not exacerbated in PCVS males; rather, they appeared to better cope with SUB status than NS SUB males. They had lower basal plasma corticosterone than NS SUB males at the end of VBS housing. In situ hybridization for CRH in the PVN and CeA did not reveal any prenatal treatment or status effects, while NPY expression was higher within the MeA of dominant and subordinate males exposed to the VBS in comparison with controls, but with no effect of prenatal treatment. These data suggest that prenatal chronic variable stress may confer resilience to offspring when exposed to social stress in adulthood., (Copyright © 2017 Elsevier Inc. All rights reserved.)
- Published
- 2017
- Full Text
- View/download PDF
35. Editorial.
- Author
-
Krause EG, Reagan LP, and Tamashiro KL
- Subjects
- Behavior physiology, History, 20th Century, History, 21st Century, Humans, Obesity metabolism, Sodium Chloride, Dietary administration & dosage, Stress, Physiological, United States, Neurosciences history, Obesity etiology, Sodium Chloride, Dietary adverse effects
- Published
- 2017
- Full Text
- View/download PDF
36. A Single Angiotensin II Hypertensive Stimulus Is Associated with Prolonged Neuronal and Immune System Activation in Wistar-Kyoto Rats.
- Author
-
Zubcevic J, Santisteban MM, Perez PD, Arocha R, Hiller H, Malphurs WL, Colon-Perez LM, Sharma RK, de Kloet A, Krause EG, Febo M, and Raizada MK
- Abstract
Activation of autonomic neural pathways by chronic hypertensive stimuli plays a significant role in pathogenesis of hypertension. Here, we proposed that even a single acute hypertensive stimulus will activate neural and immune pathways that may be important in initiation of memory imprinting seen in chronic hypertension. We investigated the effects of acute angiotensin II (Ang II) administration on blood pressure, neural activation in cardioregulatory brain regions, and central and systemic immune responses, at 1 and 24 h post-injection. Administration of a single bolus intra-peritoneal (I.P.) injection of Ang II (36 μg/kg) resulted in a transient increase in the mean arterial pressure (MAP) (by 22 ± 4 mmHg vs saline), which returned to baseline within 1 h. However, in contrast to MAP, neuronal activity, as measured by manganese-enhanced magnetic resonance (MEMRI), remained elevated in several cardioregulatory brain regions over 24 h. The increase was predominant in autonomic regions, such as the subfornical organ (SFO; ~20%), paraventricular nucleus of the hypothalamus (PVN; ~20%) and rostral ventrolateral medulla (RVLM; ~900%), among others. Similarly, systemic and central immune responses, as evidenced by circulating levels of CD4
+ /IL17+ T cells, and increased IL17 levels and activation of microglia in the PVN, respectively, remained elevated at 24 h following Ang II challenge. Elevated Fos expression in the PVN was also present at 24 h (by 73 ± 11%) following Ang II compared to control saline injections, confirming persistent activation of PVN. Thus, even a single Ang II hypertensive stimulus will initiate changes in neuronal and immune cells that play a role in the developing hypertensive phenotype.- Published
- 2017
- Full Text
- View/download PDF
37. Post-stroke angiotensin II type 2 receptor activation provides long-term neuroprotection in aged rats.
- Author
-
Bennion DM, Isenberg JD, Harmel AT, DeMars K, Dang AN, Jones CH, Pignataro ME, Graham JT, Steckelings UM, Alexander JC, Febo M, Krause EG, de Kloet AD, Candelario-Jalil E, and Sumners C
- Subjects
- Animals, Female, Male, Mice, Rats, Rats, Sprague-Dawley, Neuroprotective Agents pharmacology, Receptor, Angiotensin, Type 2 agonists, Stroke physiopathology
- Abstract
Activation of the angiotensin II type 2 receptor (AT2R) by administration of Compound 21 (C21), a selective AT2R agonist, induces neuroprotection in models of ischemic stroke in young adult animals. The mechanisms of this neuroprotective action are varied, and may include direct and indirect effects of AT2R activation. Our objectives were to assess the long-term protective effects of post-stroke C21 treatments in a clinically-relevant model of stroke in aged rats and to characterize the cellular localization of AT2Rs in the mouse brain of transgenic reporter mice following stroke. Intraperitoneal injections of C21 (0.03mg/kg) after ischemic stroke induced by transient monofilament middle cerebral artery occlusion resulted in protective effects that were sustained for up to at least 3-weeks post-stroke. These included improved neurological function across multiple assessments and a significant reduction in infarct volume as assessed by magnetic resonance imaging. We also found AT2R expression to be on neurons, not astrocytes or microglia, in normal female and male mouse brains. Stroke did not induce altered cellular localization of AT2R when assessed at 7 and 14 days post-stroke. These findings demonstrate that the neuroprotection previously characterized only during earlier time points using stroke models in young animals is sustained long-term in aged rats, implying even greater clinical relevance for the study of AT2R agonists for the acute treatment of ischemic stroke in human disease. Further, it appears that this sustained neuroprotection is likely due to a mix of both direct and indirect effects stemming from selective activation of AT2Rs on neurons or other cells besides astrocytes and microglia.
- Published
- 2017
- Full Text
- View/download PDF
38. Chronic salt-loading reduces basal excitatory input to CRH neurons in the paraventricular nucleus and accelerates recovery from restraint stress in male mice.
- Author
-
Krause EG, Pati D, and Frazier CJ
- Subjects
- Animals, Area Under Curve, Corticotropin-Releasing Hormone genetics, Drinking drug effects, Electric Stimulation, Excitatory Amino Acid Antagonists pharmacology, Excitatory Postsynaptic Potentials drug effects, Luminescent Proteins genetics, Luminescent Proteins metabolism, Male, Mice, Mice, Transgenic, Mutation genetics, Neurons physiology, Patch-Clamp Techniques, Quinoxalines pharmacology, RNA, Messenger metabolism, Restraint, Physical, Sodium blood, Time Factors, Valine analogs & derivatives, Valine pharmacology, Corticotropin-Releasing Hormone metabolism, Neurons drug effects, Paraventricular Hypothalamic Nucleus cytology, Recovery of Function drug effects, Salts pharmacology
- Abstract
Neurons synthesizing corticotrophin-releasing hormone (CRH) in the paraventricular nucleus of the hypothalamus (PVN) are activated during acute stress and act via the hypothalamic-pituitary-adrenal (HPA) axis to increase systemic levels of corticosterone (CORT). Recent data indicates that CRH neurons in the PVN are inhibited by acute salt-loading, and that this inhibition blunts the response to restraint stress as measured by increases in plasma CORT. The current study evaluates the effects of chronic rather than acute salt-loading on stress-induced activation of the HPA axis. Relative to euhydrated controls, chronic salt-loading over a 5-day period elevated plasma sodium and fluid intake without eliciting hypovolemia or substantial alterations in food intake or body weight. Chronic salt-loading also decreased expression of CRH mRNA in the anterior but not posterior portion of the PVN. Similarly, whole cell patch clamp recordings revealed that salt-loading effectively decreases spontaneous excitatory input to CRH neurons in the PVN without altering spontaneous inhibitory input. Generally consistent with these observations, chronic salt attenuated HPA axis activation as indicated by a significant reduction of plasma CORT during recovery from restraint stress., (Copyright © 2017. Published by Elsevier Inc.)
- Published
- 2017
- Full Text
- View/download PDF
39. Targeting psychologic stress signaling pathways in Alzheimer's disease.
- Author
-
Futch HS, Croft CL, Truong VQ, Krause EG, and Golde TE
- Subjects
- Animals, Disease Models, Animal, Humans, Signal Transduction physiology, Alzheimer Disease metabolism, Amyloid beta-Peptides metabolism, Neurons metabolism, Stress, Psychological metabolism
- Abstract
Alzheimer's Disease (AD) is the most prevalent progressive neurodegenerative disease; to date, no AD therapy has proven effective in delaying or preventing the disease course. In the search for novel therapeutic targets in AD, it has been shown that increased chronic psychologic stress is associated with AD risk. Subsequently, biologic pathways underlying psychologic stress have been identified and shown to be able to exacerbate AD relevant pathologies. In this review, we summarize the literature relevant to the association between psychologic stress and AD, focusing on studies investigating the effects of stress paradigms on transgenic mouse models of Amyloid-β (Aβ) and tau pathologies. In recent years, a substantial amount of research has been done investigating a key stress-response mediator, corticotropin-releasing hormone (CRH), and its interactions with AD relevant processes. We highlight attempts to target the CRH signaling pathway as a therapeutic intervention in these transgenic mouse models and discuss how targeting this pathway is a promising avenue for further investigation.
- Published
- 2017
- Full Text
- View/download PDF
40. Oxytocin receptors are expressed on dopamine and glutamate neurons in the mouse ventral tegmental area that project to nucleus accumbens and other mesolimbic targets.
- Author
-
Peris J, MacFadyen K, Smith JA, de Kloet AD, Wang L, and Krause EG
- Subjects
- Animals, Dopamine metabolism, Glutamic Acid metabolism, Image Processing, Computer-Assisted, Immunohistochemistry, In Situ Hybridization, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Neural Pathways metabolism, Neurons metabolism, Nucleus Accumbens metabolism, Receptors, Oxytocin biosynthesis, Ventral Tegmental Area metabolism
- Abstract
The mesolimbic dopamine (DA) circuitry determines which behaviors are positively reinforcing and therefore should be encoded in the memory to become a part of the behavioral repertoire. Natural reinforcers, like food and sex, activate this pathway, thereby increasing the likelihood of further consummatory, social, and sexual behaviors. Oxytocin (OT) has been implicated in mediating natural reward and OT-synthesizing neurons project to the ventral tegmental area (VTA) and nucleus accumbens (NAc); however, direct neuroanatomical evidence of OT regulation of DA neurons within the VTA is sparse. To phenotype OT-receptor (OTR) expressing neurons originating within the VTA, we delivered Cre-inducible adeno-associated virus that drives the expression of fluorescent marker into the VTA of male mice that had Cre-recombinase driven by OTR gene expression. OTR-expressing VTA neurons project to NAc, prefrontal cortex, the extended amygdala, and other forebrain regions but less than 10% of these OTR-expressing neurons were identified as DA neurons (defined by tyrosine hydroxylase colocalization). Instead, almost 50% of OTR-expressing cells in the VTA were glutamate (GLU) neurons, as indicated by expression of mRNA for the vesicular GLU transporter (vGluT). About one-third of OTR-expressing VTA neurons did not colocalize with either DA or GLU phenotypic markers. Thus, OTR expression by VTA neurons implicates that OT regulation of reward circuitry is more complex than a direct action on DA neurotransmission. J. Comp. Neurol. 525:1094-1108, 2017. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)
- Published
- 2017
- Full Text
- View/download PDF
41. A Unique "Angiotensin-Sensitive" Neuronal Population Coordinates Neuroendocrine, Cardiovascular, and Behavioral Responses to Stress.
- Author
-
de Kloet AD, Wang L, Pitra S, Hiller H, Smith JA, Tan Y, Nguyen D, Cahill KM, Sumners C, Stern JE, and Krause EG
- Subjects
- Animals, Female, Hormones metabolism, Male, Mice, Mice, Inbred C57BL, Behavior, Animal physiology, Blood Pressure physiology, Neurons physiology, Neurosecretory Systems physiology, Paraventricular Hypothalamic Nucleus physiology, Receptor, Angiotensin, Type 1 metabolism, Stress, Physiological physiology
- Abstract
Stress elicits neuroendocrine, autonomic, and behavioral responses that mitigate homeostatic imbalance and ensure survival. However, chronic engagement of such responses promotes psychological, cardiovascular, and metabolic impairments. In recent years, the renin-angiotensin system has emerged as a key mediator of stress responding and its related pathologies, but the neuronal circuits that orchestrate these interactions are not known. These studies combine the use of the Cre-recombinase/loxP system in mice with optogenetics to structurally and functionally characterize angiotensin type-1a receptor-containing neurons of the paraventricular nucleus of the hypothalamus, the goal being to determine the extent of their involvement in the regulation of stress responses. Initial studies use neuroanatomical techniques to reveal that angiotensin type-1a receptors are localized predominantly to the parvocellular neurosecretory neurons of the paraventricular nucleus of the hypothalamus. These neurons are almost exclusively glutamatergic and send dense projections to the exterior portion of the median eminence. Furthermore, these neurons largely express corticotrophin-releasing hormone or thyrotropin-releasing hormone and do not express arginine vasopressin or oxytocin. Functionally, optogenetic stimulation of these neurons promotes the activation of the hypothalamic-pituitary-adrenal and hypothalamic-pituitary-thyroid axes, as well as a rise in systolic blood pressure. When these neurons are optogenetically inhibited, the activity of these neuroendocrine axes are suppressed and anxiety-like behavior in the elevated plus maze is dampened. Collectively, these studies implicate this neuronal population in the integration and coordination of the physiological responses to stress and may therefore serve as a potential target for therapeutic intervention for stress-related pathology. SIGNIFICANCE STATEMENT Chronic stress leads to an array of physiological responses that ultimately rouse psychological, cardiovascular, and metabolic impairments. As a consequence, there is an urgent need for the development of novel therapeutic approaches to prevent or dampen deleterious aspects of "stress." While the renin-angiotensin system has received some attention in this regard, the neural mechanisms by which this endocrine system may impact stress-related pathologies and consequently serve as targets for therapeutic intervention are not clear. The present studies provide substantial insight in this regard. That is, they reveal that a distinct population of angiotensin-sensitive neurons is integral to the coordination of stress responses. The implication is that this neuronal phenotype may serve as a target for stress-related disease., (Copyright © 2017 the authors 0270-6474/17/373479-13$15.00/0.)
- Published
- 2017
- Full Text
- View/download PDF
42. Angiotensin type 1a receptors in the paraventricular nucleus of the hypothalamus control cardiovascular reactivity and anxiety-like behavior in male mice.
- Author
-
Wang L, Hiller H, Smith JA, de Kloet AD, and Krause EG
- Subjects
- Animals, Blood Pressure physiology, Corticotropin-Releasing Hormone metabolism, Heart Rate physiology, Male, Mice, Mice, Knockout, Pituitary-Adrenal System metabolism, RNA, Messenger metabolism, Stress, Physiological physiology, Sympathetic Nervous System metabolism, Anxiety metabolism, Cardiovascular System metabolism, Hypothalamo-Hypophyseal System metabolism, Paraventricular Hypothalamic Nucleus metabolism, Receptor, Angiotensin, Type 1 metabolism
- Abstract
This study tested the hypothesis that deletion of angiotensin type 1a receptors (AT1a) from the paraventricular nucleus of hypothalamus (PVN) attenuates anxiety-like behavior, hypothalamic-pituitary-adrenal (HPA) axis activity, and cardiovascular reactivity. We used the Cre/LoxP system to generate male mice with AT1a specifically deleted from the PVN. Deletion of the AT1a from the PVN reduced anxiety-like behavior as indicated by increased time spent in the open arms of the elevated plus maze. In contrast, PVN AT1a deletion had no effect on HPA axis activation subsequent to an acute restraint challenge but did reduce hypothalamic mRNA expression for corticotropin-releasing hormone (CRH). To determine whether PVN AT1a deletion inhibits cardiovascular reactivity, we measured systolic blood pressure, heart rate, and heart rate variability (HRV) using telemetry and found that PVN AT1a deletion attenuated restraint-induced elevations in systolic blood pressure and elicited changes in HRV indicative of reduced sympathetic nervous activity. Consistent with the decreased HRV, PVN AT1a deletion also decreased adrenal weight, suggestive of decreased adrenal sympathetic outflow. Interestingly, the altered stress responsivity of mice with AT1a deleted from the PVN was associated with decreased hypothalamic microglia and proinflammatory cytokine expression. Collectively, these results suggest that deletion of AT1a from the PVN attenuates anxiety, CRH gene transcription, and cardiovascular reactivity and reduced brain inflammation may contribute to these effects., (Copyright © 2016 the American Physiological Society.)
- Published
- 2016
- Full Text
- View/download PDF
43. Angiotensin Type-2 Receptors Influence the Activity of Vasopressin Neurons in the Paraventricular Nucleus of the Hypothalamus in Male Mice.
- Author
-
de Kloet AD, Pitra S, Wang L, Hiller H, Pioquinto DJ, Smith JA, Sumners C, Stern JE, and Krause EG
- Subjects
- Animals, GABAergic Neurons cytology, GABAergic Neurons metabolism, Green Fluorescent Proteins genetics, Green Fluorescent Proteins metabolism, Male, Mice, Mice, Inbred C57BL, Mice, Transgenic, Receptor, Angiotensin, Type 2 genetics, Synapses metabolism, Arginine Vasopressin metabolism, Neurons metabolism, Paraventricular Hypothalamic Nucleus cytology, Paraventricular Hypothalamic Nucleus metabolism, Receptor, Angiotensin, Type 2 physiology
- Abstract
It is known that angiotensin-II acts at its type-1 receptor to stimulate vasopressin (AVP) secretion, which may contribute to angiotensin-II-induced hypertension. Less well known is the impact of angiotensin type-2 receptor (AT2R) activation on these processes. Studies conducted in a transgenic AT2R enhanced green fluorescent protein reporter mouse revealed that although AT2R are not themselves localized to AVP neurons within the paraventricular nucleus of the hypothalamus (PVN), they are localized to neurons that extend processes into the PVN. In the present set of studies, we set out to characterize the origin, phenotype, and function of nerve terminals within the PVN that arise from AT2R-enhanced green fluorescent protein-positive neurons and synapse onto AVP neurons. Initial experiments combined genetic and neuroanatomical techniques to determine that γ-aminobutyric acid (GABA)ergic neurons derived from the peri-PVN area containing AT2R make appositions onto AVP neurons within the PVN, thereby positioning AT2R to negatively regulate neuroendocrine secretion. Subsequent patch-clamp electrophysiological experiments revealed that selective activation of AT2R in the peri-PVN area using compound 21 facilitates inhibitory (ie, GABAergic) neurotransmission and leads to reduced activity of AVP neurons within the PVN. Final experiments determined the functional impact of AT2R activation by testing the effects of compound 21 on plasma AVP levels. Collectively, these experiments revealed that AT2R expressing neurons make GABAergic synapses onto AVP neurons that inhibit AVP neuronal activity and suppress baseline systemic AVP levels. These findings have direct implications in the targeting of AT2R for disorders of AVP secretion and also for the alleviation of high blood pressure.
- Published
- 2016
- Full Text
- View/download PDF
44. Conditioned stress prevents cue-primed cocaine reinstatement only in stress-responsive rats.
- Author
-
Hadad NA, Wu L, Hiller H, Krause EG, Schwendt M, and Knackstedt LA
- Subjects
- Amygdala drug effects, Animals, Cocaine-Related Disorders genetics, Cocaine-Related Disorders metabolism, Cocaine-Related Disorders physiopathology, Corticosterone blood, Corticotropin-Releasing Hormone genetics, Corticotropin-Releasing Hormone metabolism, Cues, Disease Models, Animal, Hippocampus drug effects, Hippocampus physiopathology, Male, Rats, Rats, Sprague-Dawley, Reflex, Startle drug effects, Self Administration, Stress, Psychological genetics, Stress, Psychological metabolism, Cocaine pharmacology, Dopamine Uptake Inhibitors pharmacology, Extinction, Psychological drug effects, Stress, Psychological physiopathology
- Abstract
Neurobiological mechanisms underlying comorbid posttraumatic stress disorder (PTSD) and cocaine use disorder (CUD) are unknown. We aimed to develop an animal model of PTSD + CUD to examine the neurobiology underlying cocaine-seeking in the presence of PTSD comorbidity. Rats were exposed to cat urine once for 10-minutes and tested for anxiety-like behaviors one week later. Subsequently, rats underwent long-access (LgA) cocaine self-administration and extinction training. Rats were re-exposed to the trauma context and then immediately tested for cue-primed reinstatement of cocaine-seeking. Plasma and brains were collected afterwards for corticosterone assays and real-time qPCR analysis. Urine-exposed (UE; n = 23) and controls not exposed to urine (Ctrl; n = 11) did not differ in elevated plus maze behavior, but UE rats displayed significantly reduced habituation of the acoustic startle response (ASR) relative to Ctrl rats. A median split of ASR habituation scores was used to classify stress-responsive rats. UE rats (n = 10) self-administered more cocaine on Day 1 of LgA than control rats (Ctrl + Coc; n = 8). Re-exposure to the trauma context prevented cocaine reinstatement only in stress-responsive rats. Ctrl + Coc rats had lower plasma corticosterone concentrations than Ctrls, and decreased gene expression of corticotropin releasing hormone (CRH) and Glcci1 in the hippocampus. Rats that self-administered cocaine displayed greater CRH expression in the amygdala that was independent of urine exposure. While we did not find that cat urine exposure induced a PTSD-like phenotype in our rats, the present study underscores the need to separate stressed rats into cohorts based on anxiety-like behavior in order to study individual vulnerability to PTSD + CUD.
- Published
- 2016
- Full Text
- View/download PDF
45. Increasing brain angiotensin converting enzyme 2 activity decreases anxiety-like behavior in male mice by activating central Mas receptors.
- Author
-
Wang L, de Kloet AD, Pati D, Hiller H, Smith JA, Pioquinto DJ, Ludin JA, Oh SP, Katovich MJ, Frazier CJ, Raizada MK, and Krause EG
- Subjects
- Angiotensin II administration & dosage, Angiotensin II analogs & derivatives, Angiotensin-Converting Enzyme 2, Animals, Basolateral Nuclear Complex drug effects, Inhibitory Postsynaptic Potentials, Male, Mice, Mice, Inbred C57BL, Neurons drug effects, Peptide Fragments administration & dosage, Proto-Oncogene Mas, Proto-Oncogene Proteins antagonists & inhibitors, Proto-Oncogene Proteins c-fos metabolism, RNA, Messenger metabolism, Receptors, G-Protein-Coupled antagonists & inhibitors, Septal Nuclei drug effects, gamma-Aminobutyric Acid metabolism, Anxiety enzymology, Basolateral Nuclear Complex enzymology, Neurons enzymology, Peptidyl-Dipeptidase A metabolism, Proto-Oncogene Proteins metabolism, Receptors, G-Protein-Coupled metabolism, Septal Nuclei enzymology
- Abstract
Over-activation of the brain renin-angiotensin system (RAS) has been implicated in the etiology of anxiety disorders. Angiotensin converting enzyme 2 (ACE2) inhibits RAS activity by converting angiotensin-II, the effector peptide of RAS, to angiotensin-(1-7), which activates the Mas receptor (MasR). Whether increasing brain ACE2 activity reduces anxiety by stimulating central MasR is unknown. To test the hypothesis that increasing brain ACE2 activity reduces anxiety-like behavior via central MasR stimulation, we generated male mice overexpressing ACE2 (ACE2 KI mice) and wild type littermate controls (WT). ACE2 KI mice explored the open arms of the elevated plus maze (EPM) significantly more than WT, suggesting increasing ACE2 activity is anxiolytic. Central delivery of diminazene aceturate, an ACE2 activator, to C57BL/6 mice also reduced anxiety-like behavior in the EPM, but centrally administering ACE2 KI mice A-779, a MasR antagonist, abolished their anxiolytic phenotype, suggesting that ACE2 reduces anxiety-like behavior by activating central MasR. To identify the brain circuits mediating these effects, we measured Fos, a marker of neuronal activation, subsequent to EPM exposure and found that ACE2 KI mice had decreased Fos in the bed nucleus of stria terminalis but had increased Fos in the basolateral amygdala (BLA). Within the BLA, we determined that ∼62% of GABAergic neurons contained MasR mRNA and expression of MasR mRNA was upregulated by ACE2 overexpression, suggesting that ACE2 may influence GABA neurotransmission within the BLA via MasR activation. Indeed, ACE2 overexpression was associated with increased frequency of spontaneous inhibitory postsynaptic currents (indicative of presynaptic release of GABA) onto BLA pyramidal neurons and central infusion of A-779 eliminated this effect. Collectively, these results suggest that ACE2 may reduce anxiety-like behavior by activating central MasR that facilitate GABA release onto pyramidal neurons within the BLA., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
46. Reporter mouse strain provides a novel look at angiotensin type-2 receptor distribution in the central nervous system.
- Author
-
de Kloet AD, Wang L, Ludin JA, Smith JA, Pioquinto DJ, Hiller H, Steckelings UM, Scheuer DA, Sumners C, and Krause EG
- Subjects
- Animals, Brain metabolism, GABAergic Neurons metabolism, Hypothalamus metabolism, Immunohistochemistry, Male, Mice, Mice, Transgenic, Models, Animal, Paraventricular Hypothalamic Nucleus metabolism, Preoptic Area metabolism, RNA, Messenger metabolism, Tyrosine 3-Monooxygenase metabolism, Vesicular Glutamate Transport Protein 2 metabolism, Central Nervous System metabolism, Receptor, Angiotensin, Type 2 metabolism
- Abstract
Angiotensin-II acts at its type-1 receptor (AT1R) in the brain to regulate body fluid homeostasis, sympathetic outflow and blood pressure. However, the role of the angiotensin type-2 receptor (AT2R) in the neural control of these processes has received far less attention, largely because of limited ability to effectively localize these receptors at a cellular level in the brain. The present studies combine the use of a bacterial artificial chromosome transgenic AT2R-enhanced green fluorescent protein (eGFP) reporter mouse with recent advances in in situ hybridization (ISH) to circumvent this obstacle. Dual immunohistochemistry (IHC)/ISH studies conducted in AT2R-eGFP reporter mice found that eGFP and AT2R mRNA were highly co-localized within the brain. Qualitative analysis of eGFP immunoreactivity in the brain then revealed localization to neurons within nuclei that regulate blood pressure, metabolism, and fluid balance (e.g., NTS and median preoptic nucleus [MnPO]), as well as limbic and cortical areas known to impact stress responding and mood. Subsequently, dual IHC/ISH studies uncovered the phenotype of specific populations of AT2R-eGFP cells. For example, within the NTS, AT2R-eGFP neurons primarily express glutamic acid decarboxylase-1 (80.3 ± 2.8 %), while a smaller subset express vesicular glutamate transporter-2 (18.2 ± 2.9 %) or AT1R (8.7 ± 1.0 %). No co-localization was observed with tyrosine hydroxylase in the NTS. Although AT2R-eGFP neurons were not observed within the paraventricular nucleus (PVN) of the hypothalamus, eGFP immunoreactivity is localized to efferents terminating in the PVN and within GABAergic neurons surrounding this nucleus. These studies demonstrate that central AT2R are positioned to regulate blood pressure, metabolism, and stress responses.
- Published
- 2016
- Full Text
- View/download PDF
47. Cross talk between AT1 receptors and Toll-like receptor 4 in microglia contributes to angiotensin II-derived ROS production in the hypothalamic paraventricular nucleus.
- Author
-
Biancardi VC, Stranahan AM, Krause EG, de Kloet AD, and Stern JE
- Subjects
- Angiotensin II immunology, Angiotensin II Type 1 Receptor Blockers pharmacology, Animals, Anti-Bacterial Agents pharmacology, Immunity, Innate immunology, Inflammation, Losartan pharmacology, Male, Mice, Mice, Inbred C3H, Mice, Knockout, Microglia drug effects, Microglia immunology, Minocycline pharmacology, Oxidative Stress genetics, Oxidative Stress immunology, Paraventricular Hypothalamic Nucleus drug effects, Paraventricular Hypothalamic Nucleus immunology, Rats, Rats, Wistar, Reactive Oxygen Species immunology, Receptor, Angiotensin, Type 1 metabolism, Renin-Angiotensin System genetics, Renin-Angiotensin System immunology, Toll-Like Receptor 4 immunology, Angiotensin II metabolism, Microglia metabolism, Paraventricular Hypothalamic Nucleus metabolism, Reactive Oxygen Species metabolism, Receptor, Angiotensin, Type 1 genetics, Toll-Like Receptor 4 metabolism
- Abstract
ANG II is thought to increase sympathetic outflow by increasing oxidative stress and promoting local inflammation in the paraventricular nucleus (PVN) of the hypothalamus. However, the relative contributions of inflammation and oxidative stress to sympathetic drive remain poorly understood, and the underlying cellular and molecular targets have yet to be examined. ANG II has been shown to enhance Toll-like receptor (TLR)4-mediated signaling on microglia. Thus, in the present study, we aimed to determine whether ANG II-mediated activation of microglial TLR4 signaling is a key molecular target initiating local oxidative stress in the PVN. We found TLR4 and ANG II type 1 (AT1) receptor mRNA expression in hypothalamic microglia, providing molecular evidence for the potential interaction between these two receptors. In hypothalamic slices, ANG II induced microglial activation within the PVN (∼65% increase, P < 0.001), an effect that was blunted in the absence of functional TLR4. ANG II increased ROS production, as indicated by dihydroethidium fluorescence, within the PVN of rats and mice (P < 0.0001 in both cases), effects that were also dependent on the presence of functional TLR4. The microglial inhibitor minocycline attenuated ANG II-mediated ROS production, yet ANG II effects persisted in PVN single-minded 1-AT1a knockout mice, supporting the contribution of a non-neuronal source (likely microglia) to ANG II-driven ROS production in the PVN. Taken together, these results support functional interactions between AT1 receptors and TLR4 in mediating ANG II-dependent microglial activation and oxidative stress within the PVN. More broadly, our results support a functional interaction between the central renin-angiotensin system and innate immunity in the regulation of neurohumoral outflows from the PVN., (Copyright © 2016 the American Physiological Society.)
- Published
- 2016
- Full Text
- View/download PDF
48. Role of neurons and glia in the CNS actions of the renin-angiotensin system in cardiovascular control.
- Author
-
de Kloet AD, Liu M, Rodríguez V, Krause EG, and Sumners C
- Subjects
- Angiotensin II metabolism, Animals, Cardiovascular System innervation, Cell Communication, Central Nervous System physiopathology, Humans, Hypertension physiopathology, Receptor, Angiotensin, Type 1 metabolism, Blood Pressure, Cardiovascular System metabolism, Central Nervous System metabolism, Hypertension metabolism, Neuroglia metabolism, Neurons metabolism, Renin-Angiotensin System
- Abstract
Despite tremendous research efforts, hypertension remains an epidemic health concern, leading often to the development of cardiovascular disease. It is well established that in many instances, the brain plays an important role in the onset and progression of hypertension via activation of the sympathetic nervous system. Further, the activity of the renin-angiotensin system (RAS) and of glial cell-mediated proinflammatory processes have independently been linked to this neural control and are, as a consequence, both attractive targets for the development of antihypertensive therapeutics. Although it is clear that the predominant effector peptide of the RAS, ANG II, activates its type-1 receptor on neurons to mediate some of its hypertensive actions, additional nuances of this brain RAS control of blood pressure are constantly being uncovered. One of these complexities is that the RAS is now thought to impact cardiovascular control, in part, via facilitating a glial cell-dependent proinflammatory milieu within cardiovascular control centers. Another complexity is that the newly characterized antihypertensive limbs of the RAS are now recognized to, in many cases, antagonize the prohypertensive ANG II type 1 receptor (AT1R)-mediated effects. That being said, the mechanism by which the RAS, glia, and neurons interact to regulate blood pressure is an active area of ongoing research. Here, we review the current understanding of these interactions and present a hypothetical model of how these exchanges may ultimately regulate cardiovascular function., (Copyright © 2015 the American Physiological Society.)
- Published
- 2015
- Full Text
- View/download PDF
49. Neuroendocrine Function After Hypothalamic Depletion of Glucocorticoid Receptors in Male and Female Mice.
- Author
-
Solomon MB, Loftspring M, de Kloet AD, Ghosal S, Jankord R, Flak JN, Wulsin AC, Krause EG, Zhang R, Rice T, McKlveen J, Myers B, Tasker JG, and Herman JP
- Subjects
- Animals, Circadian Rhythm genetics, Feedback, Physiological, Female, Gene Knockdown Techniques, Hypothalamo-Hypophyseal System physiology, Male, Mice, Mice, Inbred C57BL, Mice, Knockout, Pituitary-Adrenal System physiology, Receptors, Glucocorticoid metabolism, Stress, Psychological genetics, Stress, Psychological metabolism, Gene Deletion, Hypothalamus metabolism, Neurosecretory Systems physiology, Receptors, Glucocorticoid genetics
- Abstract
Glucocorticoids act rapidly at the paraventricular nucleus (PVN) to inhibit stress-excitatory neurons and limit excessive glucocorticoid secretion. The signaling mechanism underlying rapid feedback inhibition remains to be determined. The present study was designed to test the hypothesis that the canonical glucocorticoid receptors (GRs) is required for appropriate hypothalamic-pituitary-adrenal (HPA) axis regulation. Local PVN GR knockdown (KD) was achieved by breeding homozygous floxed GR mice with Sim1-cre recombinase transgenic mice. This genetic approach created mice with a KD of GR primarily confined to hypothalamic cell groups, including the PVN, sparing GR expression in other HPA axis limbic regulatory regions, and the pituitary. There were no differences in circadian nadir and peak corticosterone concentrations between male PVN GR KD mice and male littermate controls. However, reduction of PVN GR increased ACTH and corticosterone responses to acute, but not chronic stress, indicating that PVN GR is critical for limiting neuroendocrine responses to acute stress in males. Loss of PVN GR induced an opposite neuroendocrine phenotype in females, characterized by increased circadian nadir corticosterone levels and suppressed ACTH responses to acute restraint stress, without a concomitant change in corticosterone responses under acute or chronic stress conditions. PVN GR deletion had no effect on depression-like behavior in either sex in the forced swim test. Overall, these findings reveal pronounced sex differences in the PVN GR dependence of acute stress feedback regulation of HPA axis function. In addition, these data further indicate that glucocorticoid control of HPA axis responses after chronic stress operates via a PVN-independent mechanism.
- Published
- 2015
- Full Text
- View/download PDF
50. Adipocyte glucocorticoid receptors mediate fat-to-brain signaling.
- Author
-
de Kloet AD, Krause EG, Solomon MB, Flak JN, Scott KA, Kim DH, Myers B, Ulrich-Lai YM, Woods SC, Seeley RJ, and Herman JP
- Subjects
- Adrenocorticotropic Hormone blood, Animals, Body Composition, Body Weight, Diet, Diet, High-Fat, Eating, Energy Metabolism physiology, Female, Hydrocortisone blood, Hypothalamo-Hypophyseal System metabolism, Male, Mice, Mice, Inbred C57BL, Neuropeptides metabolism, Obesity metabolism, Pituitary-Adrenal System metabolism, Receptors, Glucocorticoid genetics, Stress, Psychological metabolism, Adipocytes physiology, Adipose Tissue physiology, Brain physiology, Receptors, Glucocorticoid metabolism, Signal Transduction physiology
- Abstract
Stress-related (e.g., depression) and metabolic pathologies (e.g., obesity) are important and often co-morbid public health concerns. Here we identify a connection between peripheral glucocorticoid receptor (GR) signaling originating in fat with the brain control of both stress and metabolism. Mice with reduced adipocyte GR hypersecrete glucocorticoids following acute psychogenic stress and are resistant to diet-induced obesity. This hypersecretion gives rise to deficits in responsiveness to exogenous glucocorticoids, consistent with reduced negative feedback via adipocytes. Increased stress reactivity occurs in the context of elevated hypothalamic expression of hypothalamic-pituitary-adrenal (HPA) axis-excitatory neuropeptides and in the absence of altered adrenal sensitivity, consistent with a central cite of action. Our results identify a novel mechanism whereby activation of the adipocyte GR promotes peripheral energy storage while inhibiting the HPA axis, and provide functional evidence for a fat-to-brain regulatory feedback network that serves to regulate not just homeostatic energy balance but also responses to psychogenic stimuli., (Copyright © 2015 Elsevier Ltd. All rights reserved.)
- Published
- 2015
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.