Analgesic Effect And The Underlying Mechanism Of Pulse Radiofrequency Applied To Sciatic Nerve In CCI Rats

Obejective:In this study,pulsed radiofrequency(PRF)was applied to sciatic nerve ligation site in rats with sciatic nerve chronic constriction injury(CCI).pain behavior tests and molecular biological experiments such as Western blot,enzyme-linked immunosorbent assay(ELISA)were used to investigate the analgesia effect and the underlying analgesia mechanism of PRF on neuropathic pain(NP),aim to provide theoretical basis for clinical PRF treatment of neuropathic pain.Methods:Male SPF Sprague Dawley rats were randomly divided into 4 groups:S&S group:CCI sham-operation and RPF sham-operation;S&P group:CCI sham-operation and RPF operation;C&S group:CCI operation and RPF sham-operation;C&P group:CCI operation and RPF operation.Mechanical withdrawal thresholds(MWT)and thermal paw withdrawal latencies(TWL)were measured to evaluate mechanical hyperalgesia and thermal hyperalgesia in rats.PRF was applied to sciatic nerve on the 4 days after CCI for 120 seconds,with a maximum temperature of 42?.The ipsilateral MWT and TWL of rats were measured on the day before CCI(D0),the 1,3,5,7,9,11,13 and 14 days after CCI(D1,D3,D5,D7,D9,D11,D13,D14).On the 14 days after CCI,rats were killed under deep anesthesia and the ipsilateral spinal dorsal horn was dissected for the evaluation of ?-catenin protein,ionized calcium binding adapter molecule 1(Iba-1)and glial fibrillary acidic protein(GFAP)expression by Western blot,the concentration of serum inflammatory factors TNF-a and IL-1? was measured by ELISA method.Results:1.There was no significant difference in the base values(D0)of MWT and TWL among the four groups(p>0.05).Compared to the S&S group,rats in C&S group on the 1,3,5,7,9,11,13 and 14 days after CCI model(D1-D14)have significant behavioral changes,such as hallux valgus,lameness,toe curvature and foot liting,both MWT and TWL were decreased significantly,the difference was statistically significant(P<0.05,P<0.05);Compared to the C&S group,behavioral changes in C&P group rats on the 5,7,9,11,13 and 14 days after CCI model(D5-D14)such as hallux valgus,lameness,toe curvature and foot lifting were alleviated significantly,MWT and TWL increased significantly,the difference was statistically significant(p<0.05,p<0.05).2.Compared to the S&S group,the expression of ?-catenin protein in the spinal dorsal horn was increased significantly of rats in C&S group on the 14 days after CCI,the difference was statistically significant(p<0.05);Compared to the C&S group,the expression of p-catenin protein in spinal dorsal horn was down-regulated significantly of rats in C&P group on the 14 days after CCI,the difference was statistically significant(p<0.05).3.Compared to the S&S group,the expression of Iba-1 and GFAP proteins in the spinal dorsal horn was increased significantly of rats in the C&S group on the 14 days after CCI,the difference was statistically significant(p<0.05,p<0.05);Compared to the C&S group,the expression of Iba-1 and GFAP proteins in spinal dorsal horn was down-regulated significantly of rats in the C&P group on the 14 days after CCI,the difference was statistically significant(p<0.05,p<0.05).4.Compared to the S&S group,the concentration of TNF-a and IL-1? in serum were increased significantly of rats in the C&S group on the 14 days after CCI,the difference was statistically significant(p<0.05,p<0.05);Compared to the C&S group,the concentration of TNF-? and IL-1? in serum was down-regulated significantly of rats in the C&P group on the 14 days after CCI,the difference was statistically significant(p<0.05,p<0.05).Conclusion:1.Up-regulated ?-catenin protein expression in spinal dorsal horn,up-regulated activation level of microglia and astrocytes,and up-regulated TNF-? and IL-1? in serum may be involved in the neuropathic pain in CCI model rats.2.PRF applied to sciatic nerve can effectively alleviate mechanical hyperalgesia and thermal hyperalgesia in CCI model rats.3.The underlying analgesic mechanism of PRF applied to sciatic nerve may be related to inhibite ?-catenin protein expression in spinal dorsal horn,inhibite the activation level of microglia and astrocytes,and down-regulation TNF-? and IL-1? in serum.