Mechanisms underlying altered P2X3 receptor‐mediated responses in the ovariectomized rats

Abstract

P2X3 and P2X2/3 receptors appear to be expressed in peripheral tissues and dorsal root ganglia (DRG) and participate in producing peripheral pain. However, the mechanisms underlying the P2X receptors mediated nociception in the different ovarial hormone levels remain unclear. We found that after ovariectomy, the peripheral mechanical allodynic and nocifensive behavioral responses were developed, which could be reversed by P2X receptor antagonists, while the visceromotor reflex to colorectal distention was decreased, with the longer latency and higher threshold. Immunohistochemial studies revealed that P2X3 expression was significantly higher in small and medium dorsal root ganglion neurons. Real time PCR results showed that the P2X3 mRNA was in a higher level in both dorsal root ganglion neurons and rectocolon. Patch‐clamp recording results showed an increased number of cells responded to ATP with a transient current which was mediated by P2X3 receptors, while no significant change in the amplitude of current. These results indicate P2X3 is likely an important mechanism contributing to the altered receptor functions in DRG and rectocolon after ovariectomy. (Supported by NSFC No: 30570597 and program of Changjiang scholar and innovative team)