Etomidate stereospecifically stimulates forebrain,but not cerebellar, 3H-diazepam binding |
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Authors: | D Ashton R Geerts C Waterkeyn JE Leysen |
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Institution: | 1. Department of PharmacologyB-2340 Beerse, Belgium;1. Biochemical Pharmacology Janssen Pharmaceutica, B-2340 Beerse, Belgium |
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Abstract: | 3H-Diazepam binding to a total particulate fraction of rat forebrain is enhanced by (+)-etomidate and GABA, but not by (?)-etomidate. The enhancement of 3H-diazepam binding by (+)-etomidate was due to a two-fold increase in binding affinity, the maximal number of sites remained unchanged. The degree of stimulation with (+)-etomidate was higher than that obtained with GABA. THIP did not stimulate 3H-diazepam binding to forebrain, and did not reverse the enhanced binding seen with (+)-etomidate or GABA. In a synaptosomal membrane preparation of rat cerebellum, unlike (+)-etomidate, GABA and muscimol produced a marked stimulation of 3H-diazepam binding. (+)-Etomidate did not inhibit 3-muscimol binding to GABA receptors, nor did it activate or inhibit other receptor binding assays. The effects of (+)-etomidate on the benzodiazepine binding are different from those of gabamimetic drugs. It is proposed that like barbiturates, (+)-etomidate may affect benzodiazepine binding by interaction with the chloride ionophore which is coupled to the GABA-receptor. |
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