GABAA receptors on rat cerebellar granule cells are potently activated by muscimol but only slightly modulated by the benzodiazepine agonist flunitrazepam.

GABAA receptors present on rat cerebellar granule cells in culture were studied by the whole cell patch clamp technique. Muscimol appeared to be more potent than GABA itself in activating Cl(-) currents. A benzodiazepine, flunitrazepam, only slightly (10%) potentiated the GABA action.These results support the previous suggestion that GABAA receptors containing theδ subunit, such as those in the cerebellum granule cells, are potently activated by muscimol. The present results also bear out the concept that GABA action on receptors containing theδ subunit is not potentiated by benzodiazepines.