Les récepteurs P2X de l'ATP dans les neurones du système nociceptif spinal : rôle dans les douleurs neuropathiques

P2X receptors for adenosine 5′-triphosphate (ATP) are ligand-gated cation channels that play a role in intercellular communication and sensory transduction. These receptors, formed by a trimeric assembly of independent subunits, are largely distributed in various tissues including the nervous system. Currently, seven distinct P2X subunits have been identified and the P2X3 subunit is expressed by a subpopulation of peripheral nociceptors. P2X receptors, which include in their structure the P2X3 subunit appear to be involved in acute nociception. Moreover, the expression and the function of these receptors is upregulated in inflammatory pain. Concerning neuropathic pain, it appears that, in injured nerves, P2X3 is increased in intact neurones whereas it is decreased in injured neurones. Receptors, which include P2X3 seem also to participate in the development of mechanical allodynia in animal models of neuropathic pain. Other P2X receptors, in particular P2X7 receptors expressed by immune cells and P2X4 receptors expressed by microglia, play an important role in the development of neuropathic pain. Finally, it appears also that P2X receptors are important elements involved in interactions between neurones and glial cells as well as between the immune and the nervous systems.