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C Chavoix

Publications and source records attributed to C Chavoix.

24 records · Page 2Linked to original sources
PubMed1987

Benzodiazepine receptors studied in living primates by positron emission tomography: inverse agonist interactions.

The convulsant actions of methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM) and of methyl beta-carboline-3-carboxylate (beta-CCM) were evaluated in the baboon (Papio papio). DMCM, 0.6-4 mg/kg, induced epileptic seizures with short latency. DMCM convulsive seizures could be blocked by i.v. administration of the benzodiazepine agonist diazepam (10 mg). Similarly, beta-CCM, 0.3-3 mg/kg i.v., provoked generalized seizures in the baboons. These seizures were also reversed by the administration of propyl beta-carboline-3-carboxylate (3 mg/kg) or of diazepam (5 mg/kg). Combining the results from Positron Emission Tomography and the EEG assessments, benzodiazepine receptor occupancy by beta-CCM and DMCM was directly correlated with their convulsant actions in the living baboon. beta-CCM exerted its convulsant action in the living baboon at 76 and 74% benzodiazepine receptor occupancy in, respectively, occipital and temporal cortices whereas DMCM displayed a similar convulsive activity when only 58 and 65% of these receptors in the above regions were occupied.

Animals↗
PubMed1987

Pentylenetetrazol-induced seizure is not mediated by benzodiazepine receptors in vivo.

The selective benzodiazepine antagonist RO 15-1788, labelled with carbon 11 [11C] RO 15-1788, as a specific marker, together with positron emission tomography, allows the in vivo study of benzodiazepine receptors in primates. In addition, when coupled with recordings of electroencephalographic activity, this method offers the feasibility of studying the correlation between occupancy of benzodiazepine receptors and the convulsant action of drugs acting at the benzodiazepine-GABA receptor complex in vivo. The present study showed that convulsant doses of pentylenetetrazol (PTZ) could affect the binding of [11C] RO 15-1788 in vivo in two ways, depending on the doses tested: at concentrations of 20 and 30 mg/kg, pentylenetetrazol increased the binding of [11C] RO 15-1788 whereas larger concentrations displaced the binding of [11C] RO 15-1788. The direct correlation between the occupancy of respective benzodiazepine receptors, afforded by increasing convulsant doses of pentylenetetrazol, revealed that competitive interaction with benzodiazepine receptors was not necessary for pentylenetetrazol to induce the appearance of seizures in vivo.

Animals↗
PubMed1987

Relationship between mood state and information processing of negative versus positive emotional stimuli in brain-damaged patients.

The present study investigates the relationship between affective mood state as assessed by self- and hetero-rating scales and information processing of negative versus positive emotional stimuli in unilateral brain-damaged patients. Results show a high positive correlation between depressive mood scores and rating of self-awareness. Left brain-damaged (LBD) patients do not differ significantly from right brain-damaged (RBD) patients on both rating scales. RBD patients mismatch negative emotional stimuli in the nonverbal matching task. Results are discussed with reference to interaction between expression of emotion and cognition. The selective neglect of negative information is interpreted as a more basic emotional impairment.

Adult↗
PubMedDate not supplied

Relationships between benzodiazepine receptors, impairment of GABAergic transmission and convulsant activity of beta-CCM: a PET study in the baboon Papio papio.

Central type benzodiazepine receptors were studied in vivo by positron emission tomography in brain areas of 2 different groups of the baboon Papio papio: non-photosensitive (group 1) and those with an allylglycine-induced decrease in GABA-mediated inhibition (group 2). Further, a naturally photosensitive Papio papio (+3 level of photosensitive response) was compared to both groups. Regional brain binding of the specific benzodiazepine receptor ligand, [11C]Ro 15-1788, was not significantly different between groups 1 and 2. In addition, the data from the naturally photosensitive Papio papio did not seem to differ markedly from groups 1 and 2 either. Pharmacological effects of increasing doses of beta-CCM (0.05-3 mg/kg i.v.) and regional benzodiazepine receptor occupancy by the drug were simultaneously studied using electroencephalographic activity recording and positron emission tomography. A positive correlation was observed between the degree of photosensitivity of the baboon and sensitivity to the action of beta-CCM, with increasing convulsant efficacy of beta-CCM in going from group 1 to the naturally photosensitive baboon, then to group 2. Dose-related displacement curves of [11C]Ro 15-1788 binding by beta-CCM revealed that reduction in brain GABA concentration did not modify the inhibitory potency of beta-CCM on [11C]Ro 15-1788 binding in cerebral cortex. This suggests a lack of detectable in vivo allosteric effects of GABA on beta-CCM binding during beta-CCM-induced seizures. Thus, a given dose of beta-CCM displayed increasing pharmacological potency in going from baboons with the lowest photosensitivity to those with the highest, whereas benzodiazepine receptor occupancy by beta-CCM was similar in the cerebral cortex of the different baboons. Conversely, a given level of convulsant activity of beta-CCM was related to a different benzodiazepine receptor occupancy by the drug, depending on the photosensitivity of Papio papio. A given dose of a drug may, thus, have a different pharmacological potency when occupying the same number of receptors, depending on the physiopathological state of the subject.

Animals↗