Hypnotic action of ethyl beta-carboline-3-carboxylate, a benzodiazepine receptor antagonist, in cats

The present study demonstrates that ethyl beta-carboline-3-carboxylate (beta-CCE), a benzodiazepine receptor antagonist, has hypnotic and sedative actions in cats. Moreover, at a dose that does not by itself affect sleep, beta-CCE reverses the action of diazepam on sleep organization. The hypnotic effect of subcutaneous administration of beta-CCE (5 mg/kg) lasts for 3-4 h. During this period, deep slow wave sleep (deep non-REM sleep) and paradoxical sleep (REM sleep) significantly increase, while wakefulness markedly decreases. These results, which are quite opposite to the effects of benzodiazepines on sleep organization in cats, support the notion that beta-CCE also acts as a benzodiazepine antagonist of sleep organization.     

Action of suriclone in naturally and allyglycine-induced photosensitive baboons, Papio papio

Suriclone (SC) is a new anxiolytic compound with a chemical structure different from that of benzodiazepines (BZD) but SC possesses a high affinity for the so-called BZD receptors. SC was tested in the naturally or the allylglycine-treated photosensitive baboon Papio papio. As active BZD administered by the intramuscular or oral route, this new compound possesses a marked protective effect against the excessive photosensitivity of the baboons, it blocks myoclonus following EEG spike and waves discharges induced by intermittent light stimulation; as BZD again, SC can induce spontaneous myoclonus not accompanied by EEG spike and wave discharges.     

Benzodiazepine receptors studied in living primates by positron emission tomography: antagonist interactions

After labelling the brain benzodiazepine receptors of sub-human primates with [11C]RO15-1788, the interactions of different benzodiazepine receptor antagonist ligands were studied by positron emission tomography (PET). Various doses of either RO15-1788, RO15-3505 or propyl beta-carboline-3-carboxylate were injected intravenously 20 min after the radiotracer, and induced an immediate and specific dose-dependent displacement of the brain radioactivity. However, a comparison of the dose-receptor occupancy patterns of these three antagonists established from the displacement experiments revealed that only propyl beta-carboline-3-carboxylate displayed clear biphasic dose-receptor occupancy curves. This indicates that, in the living primate brain, there are two different benzodiazepine receptor subpopulations (which can be either different benzodiazepine receptor subtypes or distinct conformational states of a single receptor).     

Excessive light sensitivity in Papio papio: its variation with age, sex, and geographic origin.

Excessive sensitivity (levels 3 and 4) in a population of 1,122 Papio papio was related with age, sex, and geographical origin. (1) Age. There was no clinical response to intermittent light stimulation under the age of 5 months. These was no difference between animals 6 months to 2 years (J1) and those aged 2 to 4 years (J2). Adult females were less often light sensitive (levels 3 and 4 = 32.9%) than immature females (52.4%). Adult males could usually not be tested, but were probably less often sensitive than immature males. (2) Sex. Immature females (J1 + J2) were more often light sensitive (52.4%) than immature males (38.1%). (3) Geographical origin. No animals from East Senegal (Sansande Region) were very light sensitive. Animals from Casamance were more often light sensitive (56.2%) than those from the Niokolo-Koba National Park (N.K.N.P.) (20%). Of two samples taken at one spot between these two regions, one group resembled the population from Casamance and the second resembled that from the N.K.N.P. This observation raises several questions about the respective roles of genetic, ecological, and ethological factors.     

Cell-surface enzymes and lymphocyte functions

Recent studies have provided insights into the enzymatic functions of many surface molecules expressed by monocytes and lymphocytes. These ectoenzymes act as cell-differentiation markers of lymphomonocytic lineages; some of them are also involved in activation, signal-transduction and cell-matrix adhesion processes, as well as in the regulation of biological responses of bioactive peptides.