AUTORADIOGRAPHIC STUDY OF THE CELLULAR-LOCALIZATION OF [H-3] GLIBENCLAMIDE BINDING-SITES IN THE RAT HIPPOCAMPUS

[H-3]Glibenclamide, a potent ATP-sensitive K+ channel blocker, is a specific ligand for the identification of the sulfonylureas receptors which are closely related to ATP-sensitive K+ channels. In order to determine the pre- or postsynaptic localization of these receptors in the rat hippocampus, we studied the effects of selective kainate or colchicine-induced lesions on the regional distribution of [H-3]glibenclamide binding. A decreased binding was found in the following conditions: in CA3, after destruction of the mossy fiber terminals but not of the CA3 cells; in CA1, after destruction of the CA1 cells but not of the Schaffer collaterals; in the fascia dentata, after destruction of the granule cells. These results suggest that glibenclamide binding sites are mainly localized on the mossy fibers in CA3, and on the granular and pyramidal neurons in the fascia dentata and CA1, respectively.