The P2X receptors belong to the ligand-gated ion channel family and are activated by extracellular ATP.Overexpression of P2X4 was demonstrated in microglia and in the spinal dorsal horn following peripheral nerve injury. It has been suggested that activation of P2X4 along with p38 MAPK is essential for the development of allodynia (pain from a stimulus that doesn't normally elicit pain) following nerve injury. Inhibition of P2X4 expression in spinal microglia has been suggested as a novel therapeutic approach for the treatment of allodynia