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Background Dementia patients suffer from the progressive deterioration of cognitive and functional abilities. Instrumental disabilities usually appear in the earlier stages of the disease while basic disabilities appear in the more advanced stages. In order to differentiate between mild, moderate and severe patients both instrumental and basic functional disabilities should be taken into account simultaneously. Objectives The objective of this study was to find a new method for classifying dementia patients based on their disabilities by using a basic and an instrumental Activities of Daily Living (ADL) scale. Methods Functional disability was assessed in a Belgian cohort of dementia patients using the Katz and Lawton Instrumental Activities of Daily Living (IADL) scales. A k-means derived clustering method allocated patients to disability clusters according to their Katz and Lawton scores. In order to validate the classification, we compared socio-demographic, clinical and costs parameters between the groups. Results The clustering method allocated patients between three clusters: dependent, non-dependent with instrumental functional disability (ND-IFD) and non-dependent. Dependence, as defined by these clusters, significantly correlates with age, residential setting, MMSE, patient's quality of life and costs. Conclusion This new classification of patients suffering from dementia will provide better understanding of functional disabilities and will complement the evaluation of disease severity based on cognitive function. Copyright © 2003 John Wiley & Sons, Ltd.

This study was designed to assess the effect of 50 Hz electromagnetic fields (EMFs) on hippocampal cell cultures in the presence or absence of either sodium nitroprusside (SNP, a NO donor) or Fe2+ induced oxidative stress. One week old cultured rat hippocampal cells were exposed to either intermittent EMFs (IEMFs, 50 Hz, 0–5 mT, 1 min ON/OFF cycles, repeated 10 times every 2 h, 6 times/day during 48 h) or continuous EMFs (CEMFs, 50 Hz, 0–5 mT for 48 h). In a second set of experiments, the effect on such EMFs applied in combination with oxidative stress induced by 0.5 μM Fe2+ or SNP was estimated. At the end of both sets of experiments, cell mortality was assessed by lactate dehydrogenase measurements (LDH). Neither type of exposure to EMFs was observed to modify the basal rate of cell mortality. The exposure to CEMFs in presence of either NO or Fe2+ did not induce any significant increase in cell death. However, when cells were exposed to EMFs in the presence of NO, we observed a significant increase in cell death of 11 and 23% (P

Activity-dependent neurotrophic factor (ADNF) and a 14-amino acid fragment of this peptide (sequence VLGGGSALLRSIPA) protect neurons from death associated with an array of toxic conditions, including amyloid β-peptide, N-methyl-d-aspartate, tetrodotoxin, and the neurotoxic HIV envelope coat protein gp120. We report that an even smaller, nine-amino acid fragment (ADNF9) with the sequence SALLRSIPA potently protects cultured embryonic day 18 rat hippocampal neurons from oxidative injury and neuronal apoptosis induced by FeSO4 and trophic factor withdrawal. Among the characteristics of this protection are maintenance of mitochondrial function and a reduction in accumulation of intracellular reactive oxygen species.

The anesthetic propofol (PPF) has been shown to be an antioxidant in acellular experiments. This study was designed to assess the ability of PPF to protect primary-cultured brain cells against iron-mediated toxicity. A comparison with trolox (TX), a hydrosoluble vitamin E analogue, was performed. Rat cortical cells were exposed to 10 microM FeSO(4), PPF and/or TX. After a 4-h incubation, PPF and TX improved cell survival (lactate dehydrogenase measurements) in a concentration-dependent manner. The respective EC(50s) of each substance were 4 and 4.6 microM. The maximal effect was obtained at a 25-microM concentration which is similar to concentrations of PPF used clinically. The combination of both drugs at certain concentrations showed a complete protection of the cells, a significant decrease in intracellular peroxide production (dichloro-fluorescein diacetate (DCF-DA) fluorescence, 4-h incubation), in lipoperoxidation (thiobarbituric acid reactive substances fluorescence, PPF 6.25 microM+TX 12.5 microM) and an additive protective effect. This was true after 4- and 16-h incubation. These data suggest that PPF is neuroprotective. Moreover, the combination with a vitamin E analogue confers long duration protection against oxidative stress.

We recently have demonstrated the existence of spontaneous hyperpolarizations in midbrain dopaminergic neurons of neonatal but not adult rats. These events are mediated by the opening of apamin-sensitive K+channels after a rise in the intracellular concentration of Ca2+. They are resistant to tetrodotoxin in most cases and are probably endogenous (i.e., not synaptically activated). Here their mechanism was investigated. Cyclopiazonic acid (10 μM), a specific inhibitor of endoplasmic reticulum Ca2+ATPases, reversibly abolished the events. Caffeine, which promotes Ca2+release from intracellular stores, had concentration-dependent effects. At 1 mM, it markedly and steadily increased the frequency and the amplitude of the hyperpolarizations. At 10 mM, it induced a transient increase in their frequency followed by their cessation. All these effects were quickly reversible. Ryanodine (10 μM), which decreases the conductance of Ca2+release channels, irreversibly blocked the spontaneous hyperpolarizations. Dantrolene (100 μM), a blocker of Ca2+release from sarcoplasmic reticulum of striated muscle, did not affect the events. On the other hand, Cd2+(100–300 μM), a broad antagonist of membrane voltage-gated Ca2+channels, significantly reduced the amplitude and the frequency of the hyperpolarizations. However, when the frequency of the events was increased by 1 mM caffeine, Cd2+affected them to a smaller extent, whereas cyclopiazonic acid still abolished them. We conclude that internal stores are the major source of Ca2+ions that induce the K+channel openings underlying the spontaneous hyperpolarizations of these neurons.

Using in vitro electrophysiological procedures, we confirm the inhibitory effect of 10-(4-methylpiperazin-1-yl)pyrido[4,3-b][1, 4]benzothiazepine (JL 3), on dorsal raphe serotonergic (IC(50)=14 microM) and noradrenergic neurons (IC(50)=4.5 microM). The effect on dorsal raphe neurons was reduced by N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinyl- cyclohexanecarboxamide (WAY-100635), suggesting the importance of 5-HT(1A) receptor stimulation. Yohimbine, and ritanserin, to a lesser extent, blocked the inhibitory effect of JL 3 on locus coeruleus neurons indicating that alpha(2)-adrenoceptors and 5-HT(2A) receptors may be implicated in the effects. Because of its negligible alpha(2)-adrenoceptor affinity, the effect of JL 3 on locus coeruleus neurons, would have to be indirect. JL 3 may interfere with the norepinephrine transporter site (IC(50)=0.34 microM). JL 3 tended to reinforce the hypertensive effect of norepinephrine, while it strongly inhibited the hypertensive effect of tyramine, further indicating an interaction at the norepinephrine transporter site level.

Seutin, Vincent, Laurent Massotte, Jacqueline Scuvée-Moreau, and Albert Dresse. Spontaneous apamin-sensitive hyperpolarizations in dopaminergic neurons of neonatal rats. J. Neurophysiol. 80: 3361–3364, 1998. Intracellular recordings from substantia nigra slices revealed the existence of spontaneous hyperpolarizations (amplitude 2–8 mV, duration 100–400 ms) at −60 mV in most dopaminergic neurons of neonatal (9–15 days) but not adult rats. These events were blocked by apamin (300 nM) and bicuculline methochloride (100–300 μM), which blocks apamin-sensitive currents. They were unaffected by the selective γ-aminobutyric acid-A (GABAA) antagonists SR95531 (100 μM) and picrotoxin (30–50 μM), the GABAB antagonist CGP35348 (300 μM), the D2 antagonist haloperidol (1 μM), and the metabotropic antagonist MCPG (1 mM). The hyperpolarizations were strongly attenuated or abolished when recording electrodes contained 200 mM 1,2-bis(2-aminophenoxy)ethane- N, N, N′, N′-tetraacetic acid. They were resistant to tetrodotoxin in the majority of the cells. They had some voltage dependency and were in some cases transiently potentiated when cells were briefly depolarized by current injection. We conclude that dopaminergic neurons have developmentally regulated physiological properties. These spontaneous hyperpolarizations might affect the firing rate of these cells, which was found to be lower in neonates than in adults.

The interaction with monoamine oxidase A (MAO-A) and B has been shown to be sensitive to the absolute configuration of molecules. Therefore, the aim of this study was to compare the effects of the racemic pirlindole (a selective and reversible MAO-A inhibitor) and its two enantiomers using biochemical techniques (in vitro and ex vivo determination of rat brain MAO-A and MAO-B activity) and behavioural models (forced swimming test and reserpine-induced hypothermia and palpebral ptosis test). In vitro, the MAO-A IC50 of (+/-)-pirlindole, R-(-)-pirlindole and S-(+)-pirlindole were 0.24, 0.43 and 0.18 microM, respectively. Ex vivo, their ID50 were 24.4, 37.8 and 18.7 mg/kg i.p. The differences between the three compounds were not significant, with a ratio between the two enantiomers [R-(-)/S-(+)] of 2.2 in vitro and 2.0 ex vivo. MAO-B was only slightly inhibited. In the forced swimming test and the reserpine-induced hypothermia and ptosis model, the three compounds had an antidepressant profile. In the forced swimming test, the minimal effective dose ratio between the R-(-) and the S-(+) was again around 2.0. The behavioural observations were thus clearly in accordance with the biochemical data.

Intracellular recordings were made from neurones, presumed to be dopaminergic, in the rat midbrain slice preparation. Bicuculline methiodide (BMI) and methochloride (BMC) reversibly blocked the slow, apamin-sensitive component of the afterhyperpolarization in these cells. The IC50 for this effect was about 26 microM. In comparison, BMC antagonized the input resistance decrease evoked by muscimol (3 microM) with an IC50 of 7 microM. The base of bicuculline was less potent in blocking the slow afterhyperpolarization. SR95531 (2-[carboxy-3'-propyl]-3-amino-6-paramethoxy-phenyl-pyridaziniu m bromide), another competitive GABA(A) antagonist, and picrotoxin, a non-competitive GABA(A) antagonist, also blocked the action of muscimol (IC50s: 2 and 12 microM respectively), but had no effect on the afterhyperpolarization at a concentration of up to 100 microM. Moreover, 100 microM SR95531 did not affect the blockade of the afterhyperpolarization by BMC. This blockade persisted in the presence of tetrodotoxin and was apparently not due to a reduction of calcium entry, suggesting that it involved a direct action on the channels which mediate this afterhyperpolarization. These results strongly suggest that quaternary salts of bicuculline act on more than one target in the central nervous system. Thus, the involvement of GABA(A) receptors in a given effect cannot be proven solely on the basis of its blockade by these agents.

The effect of four KATP channel openers (KCOs) on the firing rate of CA1 pyramidal cells and A10 dopaminergic neurons was investigated using extracellular recording techniques in rat brain slices. Pinacidil, lemakalim, diazoxide and a new compound, BPDZ44, had an inhibitory effect on the electrical activity of CA1 pyramidal cells. They all had a similar potency. Only BPDZ44 and diazoxide inhibited the firing rate of A10 dopamine neurons. The sulfonylurea glipizide (1 microM) antagonized the effect of BPDZ44 and diazoxide on A10 neurons but failed to antagonize the effect of KCOs on CA1 pyramidal cells. These results show that differences exist among KCOs in their ability to decrease the electrical activity of various populations of central neurons.

JL3, 10-(4-methylpiperazin-1-yl)pyrido[4,3-b][1,4]benzothiazepine, has potent antidepressant-like activity in Porsolt's test in mice. Therefore, its influence on the electrical activity of central monoaminergic neurons was investigated in rats anaesthetized with chloral hydrate. JL3 induced a marked decrease of the firing rate of dorsal raphe serotonergic neurons (ID50 = 3.87 +/- 0.57 mg kg-1) and of locus coeruleus noradrenergic neurons (ID50 = 2.63 +/- 0.35 mg kg-1). The drug did not modify the electrical activity of A10 dopaminergic neurons. JL3 does not block amine uptake but it has affinity for 5-HT1A and 5-HT2 receptors. It is speculated that serotonergic mechanisms could play a role in the electrophysiological effects of JL3.

It has been suggested that hydrogen peroxide is involved in cascades of pathological events affecting neural cells. The aim of this study was therefore to examine whether this molecule is able by itself to modify membrane properties of pyramidal neurons in the CA1 region of the rat hippocampus. Intracellular recordings in the slice preparation showed that 3.3 mM hydrogen peroxide hyperpolarized all neurons tested (n = 41) by 11 +/- 3 mV. This effect persisted in the presence of tetrodotoxin. It developed slowly, was reversible and reproducible. In the presence of tetrodotoxin, the extrapolated reversal potential of this effect was -95 +/- 5 mV in 2.5 mM external potassium. This value was not significantly different from the one obtained with the GABAB agonist baclofen (10 microM) (-98 +/- 5 mV). It shifted when the concentration of external potassium was increased to 10.5 mM (from -96 +/- 5 to -62 +/- 4 mV), in close agreement with the Nernst equation potassium ions. The hyperpolarization was significantly reduced (by 65 +/- 22%) by the potassium channel blocker barium (100 microM). We suggest that hydrogen peroxide is able to induce an increase in potassium conductance in rat CA1 pyramidal neurons. The exact mechanism by which it produces this effect (direct action on channels or indirect effect) remains to be determined.

After heart disease, cancer and stroke, Alzheimer's disease (AD) is the fourth major cause of death in the developed countries. Due to demographic changes, this situation will further worsen in the future. With the use of molecular biology techniques, important progress has recently been made in the understanding of the molecular changes leading to some forms of this disabling illness. The first step was the partial sequencing of the amyloid protein accumulating in the senile plaques and vascular deposits characteristic of AD. This allowed the cloning of a cDNA coding for a long amyloid precursor protein (APP). During the last few years, independent reports have described the presence of several reproducible point mutations in specific codons of APP in early onset familial Alzheimer patients. These mutations are responsible for an abnormal processing of APP, leading to the formation of pathological beta/A4 amyloid deposits. beta/A4 has been shown to possess neurotrophic properties in embryonic neurones and to be a potent neurotoxic agent in differentiated hippocampal neurones. More recently, modifications of intracellular calcium, activation of kinases, free radical generation and anomalies in potassium channels have been described as possible mechanisms of beta/A4 toxicity. Some forms of Apo-E lipoprotein may be an additional risk factor. Hence, it now seems possible to elaborate a coherent theory to explain the cascade of events leading to the development of AD. Genetically induced point mutations or environmental factors may produce a modification of the APP metabolism and processing. As a consequence, abnormal deposits of beta/A4 are formed. They may exert direct or indirect neurotoxic actions. A degeneration of cholinergic, catecholaminergic and other neurones follows, leading to the well known cognitive and behavioural changes of AD.

Noradrenergic neurons have been implicated in the development of ethanol dependence and tolerance. Moreover, the development of an hyposensitivity of alpha 2 adrenoceptors has been postulated during long-term exposition to ethanol. In order to test the putative role of alpha 2 receptors in ethanol intoxication, we have studied the interaction between ethanol and yohimbine, an alpha 2 antagonist, on the spontaneous firing rate of rat locus coeruleus (LC) in an in vitro slice model. The spikes from single neurons were recorded by glass microelectrodes. Ethanol at 100 mM, a concentration that parallels the behavioral effects in the human and in the animals, inhibits the firing activity of some LC cells. This inhibition was quickly reversed after stopping the ethanol perfusion and was observed for each further administration. However, if yohimbine (20 microM) was simultaneously perfused, the ethanol-induced inhibition was rapidly antagonized. This effect is reversible after long time washout of yohimbine. This suggests that alpha 2 adrenoceptors could be implicated in the inhibitory effect of ethanol on LC noradrenergic neurons and perhaps in the development of tolerance. However, other hypotheses are discussed, because yohimbine can also antagonize other types of receptors.

The influence of acute administration of stereoisomers of fenfluramine and norfenfluramine on the firing rate of central monoaminergic neurons was investigated in rats anaesthetized with chloral hydrate. The firing rate of dorsal raphe (DR) and locus coeruleus (LC) neurons was inhibited. The parent drugs were more active on DR neurons than on LC neurons, and the converse was true for the demethylated metabolites. In both cases the d isomers were more active than the 1 isomers. No effect was observed on the electrical activity of A10 dopaminergic neurons. These differences in potency and selectivity could have therapeutic implications.

Extracellular single-cell recordings were performed on rat brain slices to compare the effects of morphine on noradrenergic neurons of the locus coeruleus (LC) and on dopaminergic neurons of the ventral tegmental area (VTA). Morphine inhibited the firing of LC neurons at very low concentrations. The mean IC50 was 13.4 +/- 1nM (mean +/- SEM) (n = 7). Moreover, the inhibitory effect of morphine was identical in slices obtained from rats anesthetized with chloral hydrate or from non-anesthetized rats. On the contrary, morphine did not have any influence on the firing of most VTA neurons (N = 20) up to 100 microM, and did not modify the sensitivity of their autoreceptors (N = 8). It is concluded that morphine potently inhibits the firing of LC neurons in vitro both in slices of anesthetized and not anesthetized animals and has no direct excitatory effect on VTA dopaminergic neurons of the rat.

A qualitative tool was recently developed for evaluation of dependency in a demented population. This tool assesses the impact of cognitive impairment on functional status, taking into account disability in both the basic and the instrumental activities of daily living. The purpose of the present paper was to study the impact of dependency on informal caregivers who assist demented patients at home, with this new useful tool. Methods: A cross-sectional analysis was undertaken of the subgroup of 145 demented patients of the National Dementia Economic Study, aged ≥65 years, living in the community, with an available caregiver. A neuropsychological assessment of patients (Mini-Mental State Examination) and a comprehensive evaluation of caregivers (quality of life, Short Form Health Survey-36, depression, Sense of Competence) were recorded. A total of 32.4% were dependent, disabled in both basic and instrumental functions, 42.1% were non-dependent but with instrumental functional disabilities and 25.5% were non-dependent. Impact of dependency on the caregiver's experience was significant for different aspects (satisfaction with caregiving, subjective burden, quality of life, depression). Medical and non-medical costs increased with the severity of functional disability. Findings indicate that this tool is also useful to assess the impact of progression of functional disability in patients with dementia, on the caregiver issues. The consequences appeared both on personal feelings and on quality of life and financial involvement in management of the patient. Cognitive impairment appears to have more moderate repercussions in these areas.

Dehydropirlindole (DHP) is the dehydroderivative of pirlindole, a short-acting inhibitor of monoamine oxidase type A (MAO-A). DHP would be formed in vivo from oxidation of pirlindole by MAO-A. The aim of this work is to compare the inhibitory potency of DHP with three reference compounds: harmaline, befloxatone and clorgyline; the two former are reversible inhibitors and the later is an irreversible inhibitor of MAO-A. Both in vitro and ex vivo assays were performed on rat brain homogenates, and IC50 and ID50 were calculated by a fluorometric method with octopamine as selective MAO-A substrate. In vitro clorgyline and befloxatone were more potent inhibitors than DHP and harmaline with IC50 values of 1.6 and 7.7 nM vs. 40 and 55 nM; ex vivo ID50 values were 1.5 and 32 micromol/kg vs. 41 and 49 micromol/kg. Befloxatone had an ID50/IC50 ratio four to five times higher than DHP and harmaline. Preincubation time experiments did not distinguish befloxatone from DHP and harmaline. In conclusion, this study shows that DHP behaves as a reversible MAO-A inhibitor whose potency is situated between that of befloxatone and harmaline.

A previous investigation has suggested that the hyperpolarization-activated cation current Ih does not contribute to the spontaneous firing of midbrain dopaminergic neurons. This conclusion was reached using Cs(-1). We have re-examined this question with extracellular recordings in slices using the more specific blocker ZD7288. In two-thirds of the cells, low concentrations of ZD7288 induced a decrease of the spontaneous firing. The maximal inhibition was about 40% and the mean IC50 was 1.6 microM. This effect was probably direct because it persisted in the presence of antagonists of various receptors. These concentrations of ZD7288 had no effect in the remaining one third of the examined cells. However, the highest concentration of ZD7288 (300 microM) abolished the firing of all dopaminergic neurons, probably by a mechanism unrelated to the blockade of Ih. We conclude that Ih controls to a certain extent the firing of a majority of midbrain dopaminergic neurons.

1. 1. Brofaromine (CGP 11305 A) belongs to a new generation of monoamine oxidase (MAO) inhibitors. These compounds induce short, reversible and selective inhibition of brain MAO of type A. 2. 2. The aim of this work is to study monoamine oxidase A (MAO-A) and monoamine oxidase B (MAO-B) activities of several rat brain regions after increasing doses of brofaromine. 3. 3. Brofaromine inhibits MAO-A activities in a dose dependent manner in all brain regions examined. 4. 4. The largest reduction was found in hippocampal formation, striatum and prefrontal cortex respectively. ID 50 is 2 times lower in hippocampus than in remaining brain. 5. 5. Brofaromine does not inhibit MAO-B activities in the different regions examined. 6. 6. Brofaromine is a very selective inhibitor of rat brain MAO-A with a preferential action on telencephalic monoaminergic nerve terminals.

Intracellular recordings were performed in rat brain slices and the pharmacology of the depolarizing effect of cholinomimetic drugs on hippocampus CA1 pyramidal cells was quantitatively investigated. Acetylcholine (ACh) and muscarine induced a concentration-dependent depolarization of these cells. The EC50 values were respectively 159 +/- 54 microM and 0.7 +/- 0.15 microM. Physostigmine (1 microM) or tacrine (1 microM) induced a marked shift in the concentration-response curve for ACh. Both drugs were equipotent in this respect. The EC50 values for ACh became, respectively, 2.4 +/- 1.5 microM and 3 +/- 0.9 microM. The depolarizing effect of ACh was completely blocked by atropine, confirming the involvement of a receptor of the muscarinic type. In order to determine the subtype of muscarinic receptor involved, the EC50 values of muscarine were determined in the presence of atropine (100 nM), pirenzepine (1 microM) or AFDX116 (10 microM). The deduced pKB for the antagonists were, respectively, 8.9, 7.4 and 6.5. Comparison with binding data suggests that M1 receptors play a prominent role in the depolarizing effect of cholinomimetic drugs on CA1 pyramidal cells.

A recently cloned rat brain cDNA derives from a novel gene, termed dendrin (DEN), expressed exclusively in forebrain structures, particularly in neocortex, olfactory bulb, hippocampus, caudate-putamen, and limbic system. In these structures, the cognate mRNA is present in neuronal cell bodies and their dendrites, whereas near exclusive dendritic localization is observed for the polypeptide product. In the hippocamus, DEN mRNA is highly expressed in the cell laminae and dendritic layers of the dentate gyrus and CA1 field, but expression is markedly reduced in the CA3 and CA4 areas. The predicted primary structure of the hydrophilic, highly basic 653-amino-acid polypeptide does not suggest a function. The restricted expression and dendritic location are compatible with a role for DEN in synaptic plasticity of central neocortical forebrain neurons.

In an in vitro electrophysiological single-cell recording model, ethanol had an inhibitory effect on locus coeruleus (LC) neurons at both low (0.1 mmol/l) and high (500 mmol/l) concentrations. In order to test if the benzodiazepine-GABA (gamma-aminobutyric acid) receptor complex could be implicated in this effect, we tested the interaction of these ethanol concentrations with picrotoxin (100 mmol/l) and RO 15-1788 (10 nmol/l). RO 15-1788 reversed the inhibitory effect induced by ethanol 500 mmol/l, but not by ethanol 0.1 mmol/l; picrotoxin reversed the effects of both concentrations. This indicates that the mechanisms of action of ethanol on LC neurons are not the same for high and low concentrations. Furthermore, the effect of concentrations related to a behavioral effect (greater than 10 mmol/l) was reversed by a low-calcium medium that abolishes transmitter release. Therefore, the inhibition induced by ethanol 500 mmol/l seems to be due to the release of an endogenous benzodiazepine-like compound.

Extracellular recordings were obtained from spontaneously active, presumed dopamine (DA) neurons of the ventral tegmental area (VTA) of the rat in a slice preparation. Bath-applied (+)-amphetamine (AMPH) (1-30 microM) induced a concentration-dependent decrease in the firing rate of these neurons, which tended to saturate with the highest concentrations used (n = 11). This inhibitory effect was dependent on the activation of D2 receptors since it was reversed by the D2 antagonist sulpiride (n = 8). However, the most striking effect of AMPH was the induction of a prominent subsensitivity of DA autoreceptors: whereas in 18 out of 20 control neurons, the D2 agonist BHT 920 (100 nM) produced a rapid and complete inhibition of the firing, this was observed in none out of 11 neurons 10 min after the end of the application of AMPH (1-30 microM) (P less than 0.001). In these cells, the mean percent inhibition produced by BHT 920 was only 47 +/- 8%. This subsensitivity remained unchanged after 20 min and declined after one hour. This effect was specific, since the sensitivity of GABAB receptors to baclofen (500 nM-1 microM) was not modified by the application of AMPH (n = 12). These results suggest that AMPH-induced DA autoreceptor subsensitivity can be produced acutely and may be the first step in a cascade of events leading to behavioral sensitization to this compound.

Extracellular recordings were obtained from spontaneously active, presumed dopaminergic neurons of the ventral tegmental area (VTA) of the rat in a slice preparation. Bath-applied N-methyl-D-aspartate (NMDA) (1-20 microM) activated all neurons tested (n = 36). This effect was clearly concentration-dependent (n = 14), quickly reversible and reproducible. No bursting type of discharge was observed during NMDA infusion. The NMDA receptor blocker DL-2-amino-5-phosphonovaleric acid (50 microM) reversibly antagonized the increase in cell firing produced with 10 microM NMDA by 83.5 +/- 3% (mean +/- S.E.M.) (n = 8, P less than 0.05). Lowering the Mg2+ concentration of the perfusion fluid to one-third of its normal value significantly enhanced the excitatory effect of 5 microM NMDA (n = 7, P less than 0.05), but not of 500 nM carbachol (n = 6). Finally, NMDA did not modify the sensitivity of dopaminergic autoreceptors of VTA neurons (n = 8), when compared to controls (n = 10). These observations strongly support the presence of specific NMDA receptors in the VTA.

The influence of a test meal on the absorption and disposition of tianeptine (Stablon), a new antidepressant, was investigated in 12 healthy subjects in a two-way, randomized, open cross-over study. Single 12.5-mg oral doses of tianeptine were administered following a night of fasting or immediately after a standardized breakfast. When subjects received tianeptine under fasting conditions the lag time before absorption onset, and the time of the maximum plasma concentration were 0.55 +/- 0.26 hours and 1.29 +/- 0.29 hours, respectively. The maximum plasma concentration was 322 +/- 44 ng/mL, and the total area under the curve 994 +/- 248 ng/hr/mL. When tianeptine was given at the end of the meal, several significant changes were found for tianeptine kinetic parameters; the lag time increased by 0.3 hour and the maximum plasma concentration was lowered (decreased by 25%) and occurred later (tmax increased by 0.5 hour). However, no significant change was found in the area under the plasma concentration-time curve. The trend and extent of changes in the MC5 metabolite parameters were similar to those observed for the parent drug. Absorption of tianeptine is slightly delayed and slowed down without modification of its extent when tianeptine is given at the end of a meal. These slight changes are not clinically relevant for an antidepressant administered three times a day. Despite the changes observed, tianeptine may be given at meal times to improve compliance with treatment.

Binedaline is a new AD acting selectively or noradrenergic systems.Clinically it is reported to differ from classical AD by its rapidity of action. In order to give experimental support to this observation chronic electrophysiological studies were initiated. The chronic administration of various AD results in an attenuation of their inhibitory effect on the firing rate of LC neurons. This attenuation probably reflects modifications in the sensitivity of some adrenoceptors. As it is usually assumed that the delayed onset of the therapeutic effectiveness of AD is related to the development of these adaptive processes, the time-course evolution of the attenuation of the inhibitory effect of binedaline and desipramine on the firing rate of LC neurons was studied. The attenuation was apparent after 9 days of treatment with binedaline and after 14 days of treatment with desipramine. These data indicate that adaptive processes develop more rapidly with binedaline and give experimental support to clinical...

After having previously studied some histochemical and biochemical aspects of the noradrenalin-containing neurons of the rat locus coeruleus (LC), we intend now to record the unitary electrophysiological activity of these neurons. In the present paper, we try to define the experimental conditions allowing a reproducible recording of this activity. In agreement with other authors, we have shown that the neurons of the LC slowly discharge, at a frequency of 1-3/sec with an amplitude of 100-150 muV. This spontaneous activity is greatly reduced by low doses of norimipramine, a tricyclic antidepressant.

The spontaneous firing rate of the noradrenergic neurons of the locus coeruleus and of the serotonergic neurons of the dorsal raphe was recorded with extracellular microelectrodes in chloral hydrate-anesthetized rats. A quantitative comparison of the effect of five tricyclic antidepressants, of tranylcypromine and of mianserin on the spontaneous activity of these two types of cells was performed. All drugs tested, except mianserin reduced the frequency of discharge of the noradrenergic neurons. Intravenous perfusion of the drugs allowed the doses required for inhibition of firing to 50% of the baseline rate (ID50) to be determined. Secondary aminated antidepressants (desipramine and nortriptyline) were more potent inhibitors than their tertiary aminated analogues (imipramine, chlorimipramine and amitriptyline). All drugs tested, except desipramine decreased the rate of firing of the serotonergic cells. In this case, the tertiary aminated antidepressants were much more potent than their secondary analogues. Mianserin was only active at very high doses. These results are in good agreement with the relative potencies of the tricyclic antidepressants for blocking the uptake of noradrenaline and serotonin into central and peripheral neurons.

Cefoxitin is a new semisynthetic cephamycin derivative with broad bactericidal activities. In order to determine the extent of the transplacental transfer of cefoxitin, 35 pregnant women received 1 Gm cefoxitin intramuscularly 15 to 180 minutes before normal or Caesarean delivery. Cefoxitin was measured microbiologically in maternal blood (multiple-time samples), umbilical blood (one-time sample), and amniotic fluid in the cases of Caesarean sections. The mammary excretion of cefoxitin injected at the same dose was investigated by measuring cefoxitin in the milk of 16 nursing mothers. In the maternal blood, a peak plasma level of approximately 25 microgram/ml was reached 30 minutes after the 1-Gm intramuscular injection. A clear-cut passage of cefoxitin in the umbilical cord blood was demonstrated. In the fetal blood, a peak level of 15 microgram/ml was obtained 45 minutes after the injection. No cefoxitin was detectable in any of the milk samples from 30 minutes to 24 hours after the 1-Gm intramuscular injection.

The principal neurochemical property of tricyclic antidepressants is the blockade of noradrenaline (NA) and/or 5-hydroxytryptamine (5-HT) uptake into monoaminergic nerve endings. Electrophysiological studies show that these drugs also decrease the firing rate of the noradrenergic neurones of the locus coeruleus (L.C.) and of the serotonergic neurones of the dorsal raphe (D.R.). In order to assess the relation between the two phenomena, the influence of five tricyclic antidepressants on NA and 5-HT uptake was studied in vitro. The concentrations required to produce a 50% inhibition (IC50) were determined and correlated with the respective doses required to reduce to 50% (ID50) the firing rate of L.C. and D.R. neurones. Ex vivo experiments were also performed to study the influence of the tricyclic antidepressants on NA and 5-HT uptake when administered i.v. at the doses decreasing to 50% the firing rate of L.C. and D.R. cells. The inhibition of the NA uptake by tricyclic antidepressants can account, at least in part, for the inhibition of the firing rate of L.C. neurones observed after acute i.v. administration. In the case of serotonergic neurons, the results do not allow a firm conclusion.

The firing rate of central locus coeruleus (LC) noradrenergic neurons and dorsal raphe (DR) serotonergic neurons was recorded in rats anaesthetized with chloral hydrate. The iontophoretic application or the i.v. perfusion of S3341, a new antihypertensive drug or clonidine decreased the frequency of discharge of LC neurons. Depending on the mode of administration clonidine was 54-63 times more potent than S3341. The selectivity of action of both drugs on alpha-2 vs. alpha-1 adrenoceptors was confirmed using yohimbine and prazosin: yohimbine completely blocked the inhibitory effect of S3341 or clonidine while prazosin did not prevent this effect. S3341 and clonidine regularly reduced the firing rate of DR neurons during i.v. perfusion but not during iontophoretic application. From these experiments is it concluded that S3341 and clonidine have a direct inhibitory effect on LC neurons via stimulation of alpha-2 autoreceptors and that both drugs have an indirect inhibitory effect on DR neurons, probably via impairment of noradrenergic transmission. Clinical studies show that S3341 induces much less sedative side effects than clonidine. In view of the great difference in the potency of these drugs to inhibit the firing rate of monoaminergic neurons which are known to be involved in sleep mechanisms, it is possible that the electrophysiological effects reported here relate to the sedative effects of these drugs.

The influence of an i.v. perfusion of buspirone on the firing rate of central monoaminergic neurons was studied in rats anaesthetized with chloral hydrate. Buspirone increased the firing rate of A10 dopaminergic neurons and blocked the inhibitory effect of iontophoretically applied dopamine on these neurons. A slight attenuation of the inhibitory effect of iontophoretically applied GABA was also observed. Buspirone increased the firing rate of locus coeruleus (LC) noradrenergic neurons and induced an attenuation of the inhibitory effect of iontophoretically applied clonidine. A slight attenuation of the inhibitory effect of iontophoretically applied GABA was also observed. Furthermore buspirone was a very potent inhibitor of the firing rate of dorsal raphe (DR) serotonergic neurons. It is concluded that activation of A10 neurons by buspirone is due to blockade of dopaminergic autoreceptors and that activation of LC neurons is related to blockade of alpha-2 autoreceptors. The significance of the interaction with gabaergic inhibition is unclear. The mechanisms involved in the inhibition of DR neurons remain to be investigated.

We studied the effects of oral administration of pimobendane on hemodynamics, blood gas levels, the renin-angiotensin system, and plasma catecholamines in 11 patients who were affected by severe chronic congestive heart failure. Following the administration of 5 mg, the cardiac index increased from 2.0 ±0.2 to 2.5 ±0.2 L/min/m2 (p

Les proprietes pharmacologiques de dix alcaloides tertiaires, hybrides et quaternaires extraits de Strychnos usambarensis ont ete examinees. Un alcaloide tertiaire, l'usambarensine, inhibe les effets muscariniques de l'acetylcholine sur l'ileon isole de rat. Quatre derives ammoniums quaternaires, la dihydrotoxiferine, l'afrocurarine (substance nouvelle), la curarine et la calebassine sont des agents curarisants tres actifs.The pharmacological properties of ten tertiary, hybrid and quaternary alkaloids isolated from the barks of Strychnos usambarensis roots have been investigated. Usambarensine, a tertiary amine derivative, inhibits the muscarinic effects of acetylcholine. Four ammonium quaternary products, dihydrotoxiferine, afrocurarine (a new substance), curarine and calebassine are potent curarizing agents.

A previous study showed a strong relationship between human focal epilepsy and the presence in the cortex of "activated" astrocytes characterized by an intense activity of dehydrogenases (DH) involved in glucose metabolism and of glutamate DH. Using the semi-chronic model of cobalt-induced experimental focal epilepsy in the rat, we investigated a possible correlation between astrocyte modifications and the chronological development of the epileptic manifestations on the ECoG. After a few days the cobalt-implanted rats present spikes, then sharp waves followed by an electrical crisis and ultimately motor seizures. Activated astrocytes were found in each phase of this evolution. Their number increases with the intensity of the manifestations. There is a close relationship between activated astrocytes and focal epileptic phenomena. At this stage of our study it is clear that the presence of activated astrocytes is not a consequence of seizures. However, it is impossible to say whether the activation is secondary to the hyperactivity of the neurons or directly responsible for the constitution of the epileptic focus. In any case, activated astrocytes provide a new means of localizing an epileptogenic focus.

The firing rate of central noradrenergic, serotonergic and dopaminergic neurons was recorded in rats anaesthetized with chloral hydrate. The i.v. perfusion of amineptine decreased the frequency of discharge of noradrenergic and dopaminergic neurons but had no effect on serotonergic cells. Quantitatively amineptine was a more potent inhibitor of dopaminergic than of noradrenergic neurons. These experiments in vivo confirm biochemical studies in vitro reporting a selective action of amineptine on dopaminergic systems.

The effect of rilmenidine (S 3341) and clonidine on the firing rate of locus ceruleus (LC) and dorsal raphe (DR) cells was studied in vivo after systemic and microiontophoretic administration. The effect of the 2 drugs was also studied in vitro on brain slices containing LC cells. Rilmenidine and clonidine inhibited the firing of LC and DR neurons. Complementary experiments performed with yohimbine and prazosin demonstrated that the effect of LC is related to an agonistic action on α 2 somatodendritic receptors, whereas the effect observed on DR cells is indirect. On LC cells, clonidine is 30 to 60 times as potent as rilmenidine. These observations may be related to less sedative effects of rilmenidine than of clonidine.

In order to find brain specific transcripts in a pUC13 cDNA library prepared from rat brain cytoplasmic poly(A)+ RNAs, the following steps were observed: 1. Randomly chosen cDNA clones from the brain library were screened by radiolabelled single stranded cDNAs (sscDNAs) prepared from liver, spleen, kidney and intestine mRNAs. 2. The brain clones containing genetic information shared with the peripheral organs were discarded. 3. After hybridization of the remaining clones with radiolabelled sscDNAs prepared from rat brain poly(A)+ RNAs, 210 possibly brain specific clones were selected. 4. Plasmids containing cDNA of each of these clones were purified and after estimation of their cDNA sizes, clones containing inserts of at least 500 base pairs (bp) were used as radiolabelled probes against rat brain, liver, spleen, kidney and intestine poly(A)+ RNAs spotted onto nitrocellulose filters (dot blot analysis). 5. By using this screening procedure, several brain specific clones were obtained. One of them (clone III 25) is presently subjected to sequencing in M13 phage. 6. A computer analysis of the partial sequence so far obtained gives no significant homology to the 15.000 genes contained in Genebank and EMBL data bank. It seems therefore that we have isolated a new brain specific cDNA coding for a not yet described peptide.

The effects of neurotensin on the spontaneous firing rate of presumed dopaminergic neurones of the ventral tegmental area of the rat, were studied in a slice preparation of brain by extracellular single-cell recordings. Bath-applied neurotensin excited all cells which were studied (N = 25). This effect was concentration-dependent; the threshold was 10(-10) M and maximal activation (about 30 spikes/10 sec) was obtained with 10(-6) M. The EC50 (half-maximal effective concentration) was roughly estimated at 35 nM. The action of neurotensin was mimicked by neurotensin 8-13 (N = 6), but not neurotensin 1-8 (N = 6). It persisted in low-calcium, high-magnesium solutions (N = 5) and therefore probably resulted from a direct activation of neurotensin receptors. The responses to neurotensin were long-lasting (30-60 min after a 10 min 10(-7) M infusion) and exhibited little tachyphylaxis. Dose-response curves to the dopaminergic agonist BHT920 showed that, during the infusion of 10(-7) M neurotensin, dopaminergic autoreceptors of some neurones were less sensitive than in control conditions. This was not a non-specific effect produced by the excitation, since it was not observed during the infusion of another excitant, N-methyl-D-aspartate (NMDA). These results show that neurotensin potently activates presumed dopaminergic neurones in the ventral tegmental area in vitro; it may also decrease the effectiveness of the autoreceptors of some neurones.

Sulmazol (AR-L 115 BS) is a new positively inotropic drug with arterial and venous vasodilating properties. We studied the effects of sulmazol (three-day infusion) on clinical tolerance, hemodynamics, and blood gas levels in ten patients with severe chronic heart failure. The hemodynamic monitoring included a Swan-Ganz catheter in the pulmonary artery and a radial catheter. Blood gas levels were determined on samples of arterial and mixed venous blood. After 24 hours of infusion, there was a significant increase in cardiac index (2 to 2.5 L/min/sq m; p less than 0.005) and a significant decrease in pulmonary wedge pressure (28 to 19 mm Hg; p less than 0.001) and in right atrial pressure (7 to 4 mm Hg; p less than 0.001) without significant changes in heart rate and systolic blood pressure. These beneficial effects lasted during the three days of infusion. Oxygen delivery was significantly increased (350 to 443 ml/min/sq m; p less than 0.005) without significant change in arterial oxygen tension. The side effects included nausea, vomiting, anorexia, and mild thrombocytopenia. We conclude that sulmazol is a potent drug which may improve severely deteriorated left and right ventricular function in patients with chronic refractory heart failure without affecting the heart rate and the systolic blood pressure.

A brain slice preparation was used to examine the effects of galanin on the spontaneous firing rate of locus coeruleus noradrenergic neurons. Galanin (10(-9)-10(-7) M), added to the bath, inhibited the firing of 14 out of 19 neurons in a concentration-dependent manner. The observed effect was quite variable, ranging from 20 to 100% at 10(-7) M. Experiments performed in low-Ca2+, high-Mg2+ medium also showed a significant inhibition by galanin (10(-7) M) in three out of five neurons, which suggests that the peptide acts directly.

The action of 5 neuroleptics and of a sedative drug on the content of dopamine (DA) and DOPAC in the rat caudate nucleus has been investigated. The neuroleptics, haloperidol, pimozide, chlorpromazine, levomepromazine, increase the DOPAC amount significantly, while the DA remains unchanged. Reserpine significantly decreases DA but also weakly the DOPAC level. Promethazine has no effect upon the DA and DOPAC level. A seasonal variation of the DA content has also been observed. The duration of the neuroleptic action on DOPAC parallels selfstimulation behaviour. A presynaptic action of these drugs may be implied in the DOPAC increase.