Diazepam-insensitive ( super(3)H)Ro 15-4513 binding in intact cultured cerebellar granule cells

( super(3)H)Ro 15-4513, a partial inverse agonist at the benzodiazepine receptor, binds to two sites in the rat cerebellum, only one of which is sensitive to diazepam. The diazepam-insensitive component, whose identity is unknown, is unique to this brain area. The authors studied the binding of ( super(3)H)Ro 15-4513 in cultured cerebellar granule cells to characterize its binding sites in a specified neuronal cell population and to determine the effects of ethanol on the binding. The diazepam-insensitive ( super(3)H)Ro 15-4513 binding site may be associated with both GABA sub(A) and benzodiazepine receptors in the cerebellar granule cells. Its physiological role as a possible mediator of the actions of benzodiazepine inverse agonists remains to be studied.