Regional distribution of sulfonylurea receptors in the brain of rodent and primate.

Glibenclamide, one of the most potent antidiabetic sulfonylureas, inhibits the activity of ATP-sensitive K+ channels in the pancreas as well as in the brain through its binding to specific receptors. Quantitative autoradiography was used to localize such receptors in the brain of rat, mouse, guinea-pig and marmoset, using [3H]glibenclamide as radioligand. In all four species, specific glibenclamide binding sites were 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 substantia 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 marmoset; in rodents, most binding sites were distributed in the fascia dentata and the CA3-CA4 fields of Ammon's horn, contrasting with a very homogeneous distribution in all subfields of the marmoset hippocampus. In conclusion, we demonstrate that primate brain contains specific binding sites for [3H]glibenclamide with a distribution not exactly similar to that in rodent brain.