REGIONAL DISTRIBUTION OF SULFONYLUREA RECEPTORS IN THE BRAIN OF RODENT AND PRIMATE

Glibenclamide, one of the most potent antidiabetic sulfonylureas, inhi bits the activity of ATP-sensitive K+ channels in the pancreas as well as in the brain through its binding to specific receptors. Quantitati ve autoradiography was used to localize such receptors in the brain of rat, mouse, guinea-pig and marmoset, using H-3!glibenclamide as radi oligand. In all four species, specific glibenclamide binding sites wer e found to be heterogeneously distributed. The highest densities were in the cerebral cortex, the molecular layer of the cerebellar cortex, the thalamus and the caudate-putamen. The globus pallidus and the subs tantia nigra were highly labelled in rat and mouse but poorly labelled in guinea-pig and marmoset. The distribution of glibenclamide binding sites in the hippocampus was different between the rodents and marmos et; in rodents, most binding sites were distributed in the fascia dent ata and the CA3-CA4 fields of Ammon's horn, contrasting with a very ho mogeneous distribution in all subfields of the marmoset hippocampus. I n conclusion, we demonstrate that primate brain contains specific bind ing sites for H-3!glibenclamide with a distribution not exactly simil ar to that in rodent brain.