Effects of NO-711 administered intrathecally on phospho-extracellular signal-regulated kinase induced by chronic constriction injury(CCI) of the sciatic nerve in rats

Objective To observe the effects of NO-711 administered intrathecally on the mechanical and heat hyperalgesia and the expression of pERK induced by CCI of the sciatic nerve in rats,and investigate the possible mechanism of NO-711 antinociceptive transmission at the spinal level.Methods One hundred and twenty six male Sprague-Dawley rats were randomized into six groups(n=21) : CCI + NO-711 50 μg(N50),CCI + NO-711 100 μg(N100),CCI + NO-711 200 μg(N200),CCI + normal saline group(CN),CCI,and sham operation(S).The mechanical withdrawal threshold(MWT) and thermal withdrawal latency(TWL) in S and CCI groups were measured before operation and 1,3,5,7,14 and 21 d after operation,respectively.Rats in N50,N100,N200 or CN groups were intrathecally cathetered 5 d before operation and administered with NO-711 or saline 5 d after CCI.The nociceptive thresholds and pERK expression in the spinal dorsal horn were measured before and after administration 30 min,1,2,4 and 8 h,respectively.Results CCI group formed steady mechanical and heat hyperalgeia from 1 d to 21 d after operation.Intrathecal administration of NO-711can increase the MWT and TWL in a dose-dependent pattern.NO-711 inhibited the expression of pERK in a dose-dependent pattern.Conclusion Intrathecal NO-711 can reduce the mechanical and heat hyperalgesia of rats via the inhibition of expression of pERK following CCI.