抄録
Extracellular ATP has been recently demonstrated to act on presynaptic P2X receptors to modulate synaptic transmission in CNS. In this study, we examined a role of P2X receptors in modulating excitatory synaptic transmission in dorsal horn neurons by using patch-clamp recordings from spinal cord slice preparations. P2X receptors were highly expressed in central terminals of both superficial and deep laminae neurons. Most presynaptic P2X receptors of lamina II neurons were not affected by bath application ofαβmATP, but activated and facilitated glutamate release by focal application ofαβmATP. In addition, these effects by focal application ofαβmATP were sensitive to PPADS and TNP-ATP. In contrast to lamina II neurons, bath application ofαβmATP activated presynaptic P2X receptors of most lamina V neurons and largely enhanced glutamate release for a relatively longer period. Moreover, presynaptic P2X receptors in most lamina V neurons were sensitive to PPADS, but resistant to TNP-ATP. These results indicate that distinct subtypes of P2X receptors are expressed in central terminals of primary afferents innervating superficial and deep dorsal horn neurons, and modulate glutamate release in a different manner. These distinct roles of presynaptic P2X receptors may serve to understand the various sensations mediated by P2X receptors. [Jpn J Physiol 54 Suppl:S169 (2004)]
