Dopamine D-5 receptor immunolocalization in rat and monkey brain

Dopamine D-5 receptor localization has been difficult because even the most specific ligands cannot distinguish between molecular subtypes of the D-1- like receptor subfamily. Antifusion protein rabbit polyclonal antibodies di rected against the C-terminus of human D-5 receptor were therefore develope d for immunolocalization of the D-5 receptor protein in brain. The antibodi es were characterized by immunoblot analysis and immunoprecipitation and us ed for light microscopic immunocytochemistry in rat and monkey brain. Affin ity purified D-5 antibodies were specific for D-5 fusion protein as well as cloned and native D-5 receptor on Western blots, and D-5 antisera specific ally immunoprecipitated solubilized, cloned D-5 receptor. Regional distribu tion of D-5 receptor immunoreactivity was consistent across species and cor related well with D-5 mRNA distribution previously reported in monkey brain . Immunoreactivity was widespread and tended to label perikarya and proxima l dendrites of neurons in cerebral cortex, basal ganglia, basal forebrain, hippocampus, diencephalon, brainstem, and cerebellum. Neuropil was immunore active in olfactory bulb, islands of Calleja, cerebral cortex, superior col liculus, and molecular layer of cerebellum. The distribution of D-5 in brai n was clearly different from that of other dopamine receptor subtypes, incl uding D-1, the other member of the D-1-like receptor subfamily. This unique distribution corroborates the idea that the D-5 receptor subtype has a dis tinct role in dopamine neurotransmission. Synapse 37:125-145, 2000. (C) 200 0 Wiley-Liss, Inc.