Abstract:

Objective  To explore the effects of flurbiprofen axetil (FA) on pain threshold and expressions of substance P (SP) and neurokinin-1 receptor (NK1-R) in muscle of rats with chronic constriction injury (CCI) of ischiadic nerve. Methods  Twenty-four male SD rats were randomly divided into 4 groups and each group has 6 rats. For group A, rats with CCI of ischiadic nerve were treated by FA (The right ischiadic nerve of rats was exposed and ligated. Behavior changes of rats were observed and pain threshold was measured before operation and 3, 6, 9, 12, and 15 d after operation. Rats were injected with FA of 5 mg/kg through tail vein when pain threshold reached peak after operation). For group B, rats with CCI of ischiadic nerve were not treated. For group C, sham operation rats were treated by FA (The ischiadic nerve of rats was exposed but was not ligated. Rats were injected with FA of 5 mg/kg through tail vein after operation). Rats of group D were sham operation rats. Expressions of SP and NK1-R in rat muscle were detected by immunohistochemistry. Results  The pain threshold of groups A and B reached peak 15 d after operation. The pain threshold of group A significantly increased after being treated by FA (P<0.05) and the pain threshold of group C also increased after being treated by FA, but the difference was not statistically significant (P>0.05). Expressions of SP and NK1-R of group A were weakly positive and those of group B were strongly positive, the difference between two groups was statistically significant (P<0.05). Expressions of SP and NK1-R of group C and group D were weakly positive and the difference was not statistically significant (P>0.05). Conclusion  The analgesia effect of FA towards chronic pain of ischiadic nerve of rats with CCI of ischiadic nerve is obviously. The mechanism may be relevant to the decrease of expressions of SP and NK1-R in muscle.

Key words: flurbiprofen axetil, ischiadic nerve, chronic constriction injury, substance P, neurokinin-1 receptor