Regional and cellular distribution of the P2Y1 purinergic receptor in the human brain: Striking neuronal localisation

The biological actions of extracellular nucleotides are exerted via two families of P2 receptors, P2X and P2Y. The metabotropic P2Y receptors comprise at least 7 distinct subtypes, which have been cloned from a number of species. However, none of the P2Y receptor proteins have been visualised yet in human brain. In the present study, the regional and cellular distribution of the P2Y1 receptor was investigated in the human brain by using immunohistochemistry. Polyclonal antibodies were raised against a synthetic peptide from the C-terminus of the P2Y1 protein. Immunoblot analysis demonstrated that P2Y1 antiserum specifically recognised a 63-kDa band in human and rat brain membranes. Similarly, the antiserum specifically detected the human P2Y1 receptor in transfected 1321N1 cells. Immunohistochemical analysis on perfusion-fixed human brain tissue showed a widespread distribution for this receptor throughout the brain. At the cellular level, the P2Y1 receptor was strikingly localised to neuronal structures of the cerebral cortex, cerebellar cortex, hippocampus, caudate nucleus, putamen, globus pallidus, subthalamic nucleus, red nucleus, and midbrain. Expression of the P2Y1 receptor was not detected in other non-neuronal cell types. These results provide the first characterisation of the cellular distribution of a P2Y receptor in the human brain. The widespread and abundant distribution of the P2Y1 receptor suggests its involvement in a number of important functions within the human brain. The neuronal localisation of this receptor points towards a possible role in neurotransmission, and also highlights a major role for extracellular nucleotides as signaling molecules within the brain. J. Comp. Neurol. 421:374–384, 2000. © 2000 Wiley-Liss, Inc.