Localization of the ATP-sensitive K+ channel regulatory subunits SUR2A and SUR2B in the rat brain

ATP-sensitive K+ (KATP) channel subunits SUR2A and SUR2B in the rat brain were investigated by RT-PCR assay, western blot analysis, in situ hybridization histochemistry, and immunohistochemical staining. The results show that the mRNA and protein of SUR2A and SUR2B are expressed in whole rat brain extracts and selected regions. SUR2 mRNA is widely expressed in many neurons and glial cells as revealed by in situ hybridization histochemistry. Immunohistochemical staining shows SUR2A to be widely expressed in neurons of the brain, especially in the large pyramidal neurons and their main dendrites in the neocortex and in the Purkinje cells of the cerebellar cortex. In contrast to SUR2A, SUR2B is potently expressed in small cells in the corpus callosum and cerebellar white matter, but is also weakly expressed in some neurons. Double immunostaining shows SUR2B to be localized in astrocytes and oligodendrocytes, while SUR2A is only localized in oligodendrocytes. These results suggest that SUR2A might be mainly a regulatory subunit of the KATP channel in most neurons and part of oligodendrocytes, while SUR2B might be mainly a regulatory subunit of the KATP channel in astrocytes, oligodendrocytes, and some neurons.

► We examined the KATP channel regulatory subunits SUR2A and SUR2B in adult rat brain. ► Extracts of whole brain and selected regions of olfactory bulb, cerebral cortex, pons and cerebellum all express mRNA and protein of these two subunits. ► SUR2A is mainly localized in brain neurons. ► SUR2B is mainly localized in glial cells.