Diverse tissue expression of rat α2-adrenergic receptor genes

Abstract

Previously, we have reported two major α2-adrenergic receptor transcripts in rat brain of 3.8 and 3.0 kb and the cloning and characterization of the rat brain complementary DNA (cDNA) (RBα2C) specific for the 3.0-kb messenger RNA. In this report, we used rat brain cDNAs specific for the 3.0 and 3.8 kb transcripts, which encode the α2C- and α2A-adrenergic receptors, respectively, and the RNGα2 cDNA, which encodes for the nonglycosylated α2B-adrenergic receptor in rat, to study tissue-specific expression of the three α2-adrenergic receptor genes in rat. To eliminate cross-hybridization of probes with transcripts from other α2 genes, we subcloned fragments that encode for the highly divergent third cytoplasmic loop of each rat α2-adrenergic receptor cDNA and used RNase protection analysis to detect specific transcripts. We show that the three rat α2-adrenergic receptor genes have diverse patterns of tissue expression, and although transcripts specific for each α2-adrenergic receptor gene are found in brain and kidney, the levels of expression of each subtype differ in these tissues. We speculate on the significance of tissue-specific expression of the α2-adrenergic receptor genes.