Pentobarbital: Dual actions to increase brain benzodiazepine receptor affinity

The binding of [³H]diazepam to benzodiazepine receptors was studied in extensively washed membranes of rat cerebral cortex in the presence of the depressant barbiturate, pentobarbital. Pentobarbital, like the endogenous neurotransmitter γ-aminobutyric acid (GABA), increased the basal binding and also potentiated the GABA-enhanced binding of [³H]diazepam to benzodiazepine receptors by increasing the apparent affinity of [ ³H]diazepam for the benzodiazepine receptor. The concentrations of pentobarbital necessary to elicit these effects in vitro are the same as those observed after treatment with pharmacologically relevant doses, suggesting that a common neurochemical association may exist between these two types of compounds.