Hypnotic action of benzodiazepines: a possible mechanism.

The objective of this investigation was to determine whether the effects of muscimol on benzodiazepine receptor binding relate to the hypnotic activity of nine benzodiazepines (clonazepam, triazolam, diazepam, flurazepam, nitrazepam, oxazepam, temazepam, clobazam, and chlordiazepoxide) and CL 218,872. There was no correlation between the basal receptor binding affinities of the drugs tested and their hypnotic potencies, whereas the benzodiazepine receptor agonists whose receptor bindings are strongly modulated by muscimol possess potent hypnotic activity. These results indicate that benzodiazepine receptors that couple to GABA receptors are involved in the hypnotic activity of the benzodiazepines.