Regional Expression Of P2Y4Receptors In The Rat Central Nervous System

P2Y receptors are G protein-coupled receptors composed of eight known subunits(P2Y_{1,2,4,6,11,12,13,14}), which are involved in different functions in neural tissue. Thepresent study investigates the expression pattern of P2Y₄receptors in the rat centralnervous systemThe specificity of the immunostaining has been verified by preabsorption, Westernblot, and combined use of immunohistochemistry and in situ hybridization. Neuronsexpressing P2Y₄receptors were distributed widely in the rat CNS. Heavy P2Y₄receptorimmunostaining was observed in the magnocellular neuroendocrine neurons of thehypothalamus, red nucleus, pontine nuclei, mesence-phalic trigeminal nucleus, motortrigeminal nucleus, ambiguous nucleus, inferior olive, hypoglossal nucleus, and dorsalmotor vagus nucleus. Both neurons and astrocytes express P2Y₄receptors. P2Y₄receptorimmunostaining signals were mainly confined to cell bodies and dendrites of neurons,suggesting that P2Y₄receptors are mainly involved in regulating postsynaptic events. Inthe hypothalamus, all the vasopressin （VP） and oxytocin （OT） neurons and all the orexinA neurons were immunoreactive for P2Y₄receptors. All the neurons expressing P2Y₄receptors were found to express N-methyl-D-aspartate receptor1（NR1）. These datasuggest that purines and pyrimidines might be involved in regulation of the release of theneuropeptides VP, OT, and orexin in the rat hypothalamus via P2Y₄receptors. Further,the physiological and pathophysiological functions of the neurons may operate throughcoupling between P2Y₄receptors and NR1.