Abstract: ObjectiveTo observe behavioral changes and the dynamic expression of cyclooxygenase-1(COX-1) in the spinal cord of rats after unilateral sciatic cryoneurolysis(SCN).Methods72 male SD rats were randomly divided into 3 groups: normal control group(N, n=6), sham group(S, n=33) and cryoneurolysis group(C, n=33). The mechanical withdrawal threshold and autotomy assession were assessed before and 1, 2, 4 weeks after operation and COX-1 immunohistochemistry was performed on L_4-6 spinal cord in 6 rats.ResultsFollowing SCN, rats exhibited significant bilateral tactile hypersensitivity until 4 weeks after operation. Furthermore, we observed autotomy peaked in severity and incidence (in 40% of rats, 1 weeks and 43.8%, 2 weeks ) 1 to 2 weeks after SCN. The COX-1 expression in dorsal horn of the spinal cord in group C was significantly higher than group S 2 and 4 weeks after operation (P<0.05).ConclusionCOX-1 plays an important role in spinal cord pain processing and central sensitization after SCN.

Key words: cyclooxygenase-1, sciatic cryoneurolysis, neuropathic pain, mechanical paw withdraw threshold