Distribution of the P2X(2) receptor subunit of the ATP-gated ion channels in the rat central nervous system

The distribution of the P2X(2) receptor subunit of the adenosine 5'-triphos phate (ATP)-gated ion channels was examined in the adult rat central nervou s system (CNS) by using P2X2 receptor-specific antisera and riboprobe-based in situ hybridisation. P2X(2) receptor mRNA expression matched the P2X(2) receptor protein localisation. An extensive expression pattern was observed , including: olfactory bulb, cerebral cortex, hippocampus, habenula, thalam ic and subthalamic nuclei, caudate putamen, posteromedial amygdalo-hippocam pal and amygdalo-cortical nuclei, substantia nigra pars compacta, ventromed ial and arcuate hypothalamic nuclei, supraoptic nucleus, tuberomammillary n ucleus, mesencephalic trigeminal nucleus, dorsal raphe, locus coeruleus, me dial parabrachial nucleus, tegmental areas, pontine nuclei, red nucleus, la teral superior olive, cochlear nuclei, spinal trigeminal nuclei, cranial mo tor nuclei, ventrolateral medulla, area postrema, nucleus of solitary tract , and cerebellar cortex. In the spinal cord, P2X(2) receptor expression was highest in the dorsal horn, with significant neuronal labeling in the vent ral horn and intermediolateral cell column. The identification of extensive P2X(2) receptor immunoreactivity and mRNA distribution within the CNS demo nstrated here provides a basis for the P2X receptor antagonist pharmacology reported in electrophysiological studies. These data support the role for extracellular ATP acting as a fast neurotransmitter at pre- and postsynapti c sites in processes such as sensory transmission, sensory-motor integratio n, motor and autonomic control, and in neuronal phenomena such as long-term potentiation (LTP) and depression (LTD). Additionally, labelling of neurog lia and fibre tracts supports a diverse role for extracellular ATP in CNS h omeostasis. (C) 1999 Wiley-Liss, Inc.