Effect of GABA and benzodiazepine antagonists on [3H]flunitrazepam binding to cerebral cortical membrane

The effects of GABA on the binding of [3H]flunitrazepam to bovine cerebral cortical membranes was investigated in presence and in absence of benzodiazepine antagonists. The percentage stimulation of [3H]flunitrazepam binding by GABA is higher when approximately 50% of the binding is displaced by benzodiazepine antagonists. The observed increase in percent stimulation of [3H]flunitrazepam binding by GABA might reflect the preferential displacement of the ligand by benzodiazepine antagonists from a GABA-insensitive conformational state or site of the receptor.