References of "Seutin, Vincent"
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See detailHydrogen Peroxide Hyperpolarizes Rat Ca1 Pyramidal Neurons by Inducing an Increase in Potassium Conductance
Seutin, Vincent ULg; Scuvée-Moreau, Jacqueline ULg; Massotte, Laurent ULg et al

in Brain Research (1995), 683(2), 275-8

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 ... [more ▼]

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. [less ▲]

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See detailEffect of dopamine and baclofen on N-methyl-D-aspartate-induced burst firing in rat ventral tegmental neurons.
Seutin, Vincent ULg; Johnson, S. W.; North, R. A.

in Neuroscience (1994), 58(1), 201-6

Intracellular microelectrode recordings were made from dopamine-containing neurons of the ventral tegmental area or substantia nigra zona compacta in rat brain slices in vitro. The firing pattern of the ... [more ▼]

Intracellular microelectrode recordings were made from dopamine-containing neurons of the ventral tegmental area or substantia nigra zona compacta in rat brain slices in vitro. The firing pattern of the neurons was switched from a tonic, single-spike pattern to a burst firing mode by adding N-methyl-D-aspartate (20 microM) to the superfusing solution; after adding tetrodotoxin the membrane potential underwent rhythmical oscillations of 20-40 mV at 0.5-2 Hz. Baclofen (1 microM) and dopamine (30 microM) hyperpolarized the neurons; when the potential was restored to its original level, the oscillations of potential and/or burst firing were not observed, but the tonic firing pattern was restored. These effects of baclofen and dopamine were prevented by barium (1 mM), which also prevented the membrane hyperpolarization. Oscillations of membrane current of a similar frequency were observed when the somatic membrane was voltage-clamped at -60 mV; these were also blocked by barium (1 mM). It is concluded that the oscillations in membrane potential observed with N-methyl-D-aspartate are generated predominantly at a dendritic location which is not voltage-clamped with an electrode at the soma. Baclofen and dopamine inhibit the oscillations by increasing the potassium conductance and hyperpolarizing the dendrites. [less ▲]

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See detailApamin increases NMDA-induced burst-firing of rat mesencephalic dopamine neurons.
Seutin, Vincent ULg; Johnson, S. W.; North, R. A.

in Brain Research (1993), 630(1-2), 341-4

Intracellular recordings made in vitro from rat midbrain dopamine neurons showed that apamin (100 nM) did not alter the regular spontaneous firing of the neurons, but it increased the occurrence of bursts ... [more ▼]

Intracellular recordings made in vitro from rat midbrain dopamine neurons showed that apamin (100 nM) did not alter the regular spontaneous firing of the neurons, but it increased the occurrence of bursts of action potentials in N-methyl-D-aspartate. Apamin appeared to facilitate burst-firing induced by NMDA because, by blocking an outward calcium-activated potassium current, it increased the depolarizing action of NMDA. [less ▲]

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See detailBurst-firing in dopamine neurons induced by N-methyl-D-aspartate : role of electrogenic sodium pump
Johnson, S.; Seutin, Vincent ULg; North, Alan

in Science (1992), 258

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See detailDifferential effects of picrotoxin and RO 15-1788 on high and low ethanol concentrations on rat locus coeruleus in vitro.
Verbanck, P. M.; Seutin, Vincent ULg; Massotte, Laurent ULg et al

in European Journal of Pharmacology (1992), 211(1), 15-21

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 ... [more ▼]

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. [less ▲]

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See detailAcute Amphetamine-Induced Subsensitivity of A10 Dopamine Autoreceptors in Vitro
Seutin, Vincent ULg; Verbanck, Paul; Massotte, Laurent ULg et al

in Brain Research (1991), 558(1), 141-4

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 ... [more ▼]

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. [less ▲]

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See detailYohimbine can induce ethanol tolerance in an in vitro preparation of rat locus coeruleus.
Verbanck, P.; Seutin, Vincent ULg; Massotte, Laurent ULg et al

in Alcoholism, Clinical & Experimental Research (1991), 15(6), 1036-9

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 ... [more ▼]

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. [less ▲]

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See detailEvidence for the presence of N-methyl-D-aspartate receptors in the ventral tegmental area of the rat : an electrophysiological in vitro study
Seutin, Vincent ULg; Verbanck, Paul; Massotte, Laurent ULg et al

in Brain Research (1990), 514(1), 147-150

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 ... [more ▼]

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. [less ▲]

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See detailElectrophysiological effects of ethanol on monoaminergic neurons: an in vivo and in vitro study.
Verbanck, P.; Seutin, Vincent ULg; Dresse, Albert ULg et al

in Alcoholism, Clinical & Experimental Research (1990), 14(5), 728-35

Monoaminergic neurons have been shown to play a role in both the intoxicating and chronic effects of ethanol. We present here the results of a study about the acute effects of ethanol on serotonergic ... [more ▼]

Monoaminergic neurons have been shown to play a role in both the intoxicating and chronic effects of ethanol. We present here the results of a study about the acute effects of ethanol on serotonergic raphe nucleus, noradrenergic locus coeruleus, and dopaminergic ventral tegmental area. These nuclei were investigated electrophysiologically by recording the spontaneous firing rate of single neurons using glass microelectrodes, both in vivo in chloral hydrate anesthetized rats and in vitro in brain slices. Ethanol was perfused intravenously at a rate ranging from 0.2 mg/kg/min to 0.2 g/kg/min in vivo, and at concentrations between 10(-8) M and 1 M in vitro. We observed that each monoaminergic nucleus had its own pattern of responses to acute ethanol perfusion, and that high and low concentrations have different actions, suggesting a biphasic effect. For example, in slices, ethanol concentrations higher than 10 mM induce an excitation in most raphe and ventral tegmental area neurons, and an inhibition of firing in locus coeruleus neurons. The results were comparable in the in vivo model, but much more heterogenous. We conclude that the effect of ethanol on the monoaminergic neurons is specific of the type of neuron, and that a biphasic effect is commonly found. [less ▲]

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See detailEffect of BHT-920 on monoaminergic neurons of the rat brain : an electrophysiological in vivo and in vitro study
Seutin, Vincent ULg; Scuvée-Moreau, Jacqueline ULg; Giesbers, Irène ULg et al

in Mededelingen van de Faculteit Landbouwwetenschappen (Rijksuniversiteit te Gent) (1990), 342

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See detailComparison of the Effect of Morphine on Locus Coeruleus Noradrenergic and Ventral Tegmental Area Dopaminergic Neurons in Vitro
Seutin, Vincent ULg; Franchimont, Nathalie; Massotte, Laurent ULg et al

in Life Sciences (1990), 46(25), 1879-85

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 ... [more ▼]

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. [less ▲]

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See detailAspects électrophysiologiques des propriétés des drogues potentiellement addictives
Seutin, Vincent ULg; Dresse, Albert ULg

in Acta Psychiatrica Belgica (1990), 90(1, Jan-Feb), 37-45

Considerable progress has been made during the last ten years in the study of the mechanism of action of addictive drugs. In this text, data concerning endogenous opioids and opiates are described. After ... [more ▼]

Considerable progress has been made during the last ten years in the study of the mechanism of action of addictive drugs. In this text, data concerning endogenous opioids and opiates are described. After a brief summary of the physiology of brain opioid systems, the various electrophysiological effects of these substances in the mammalian central nervous system are described. Finally, we summarize some experimental data allowing a better understanding of the development of tolerance and dependence to opiates in the rat. [less ▲]

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See detailGalanin Decreases the Activity of Locus Coeruleus Neurons in Vitro
Seutin, Vincent ULg; Verbanck, Paul; Massotte, Laurent ULg et al

in European Journal of Pharmacology (1989), 164(2), 373-6

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 ... [more ▼]

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. [less ▲]

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See detailAction of Rilmenidine on Locus Ceruleus and Dorsal Raphe Cells in Vivo and in Vitro
Dresse, Albert ULg; Scuvée-Moreau, Jacqueline ULg; Seutin, Vincent ULg

in American Journal of Cardiology (1988), 61(7), 32-34

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 ... [more ▼]

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 alpha 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. [less ▲]

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