DIVERSE TISSUE EXPRESSION OF RAT ALPHA(2)-ADRENERGIC RECEPTOR GENES

Previously, we have reported two major alpha2-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) (RBalpha2C) 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 alpha2C- and alpha2A-adrenergic receptors, respectively, and the RNGalpha2 cDNA, which encodes for the nonglycosylated alpha2B-adrenergic receptor in rat, to study tissue-specific expression of the three alpha2-adrenergic receptor genes in rat To eliminate cross-hybridization of probes with transcripts from other alpha2 genes, we subcloned fragments that encode for the highly divergent third cytoplasmic loop of each rat alpha2-adrenergic receptor cDNA and used RNase protection analysis to detect specific transcripts. We show that the three rat alpha2-adrenergic receptor genes have diverse patterns of tissue expression, and although transcripts specific for each alpha2-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 alpha2-adrenergic receptor genes.