Abstract:

 To investigate the changes of phosphorylated CREB in spinal cord dorsal horn of rats underwent chronic compression of dorsal root ganglia (CCD) and effects of intrathecally administer NOS inhibitor L-NAME,AG or 7-NI and cGMP  analogue 8-Br-cGMP  on the expression of pCREB in dorsal horn and the changes in thermal hyperalgesia of rats.Methods 90 male adult Wistar rats were randomly divided into L-NAME,AG,8-Br-cGMP,7-NI,Cremophor and PBS groups.Different NOS inhibitors were injected intrathecally by microsyringe at the 5th day after CCD,the thermal paw withdrawal latencies were measured before injection and  0.5,2.0,6.0,12.0,24.0 h after treatment,the anti-nociceptive effects of agents were compared.The expression of pCREB was detected by immunohistochemical analysis 2 h after intrathecal injection.Results CCD  significantly increased the expression of pCREB and pCREB positive neurons located in  all laminae of bilateral spinal cord.The expression of pCREB in ispilateral and contralateral spinal cord showed no significant difference.Compared with PBS  group,there was significant decreasing in number of pCREB positive neurons in L-NAME,AG and 7-NI groups(P<0.01），and there was markedly increasing in 8-Br-cGMP group（P<0.05）;Simultaneously,the intrathecal administer L-NAME,AG and 7-NI could  significantly reverse thermal hyperalgesia induced by CCD
.Conclusion  NO-cGMP-PKG signal pathway contribute to CCD-induced neuropathic pain.

Key words: nitric oxide；neuralgia；spinal;cAMP response-element binding protein