Effects Of High Voltage Pulsed Radiofrequency Of Dorsal Root Ganglion On Expressions Of TNF-α And IL-10 In Spinal Dorsal Horn Of SNI Rats

Objective: This study aimed to compare the analgesic efficacy of different high-voltage pulsed radiofrequency(PRF)on dorsal root ganglion(DRG),while observing the changes of TNF-ɑ and IL-10 levels in spinal dorsal horn,and to explore the analgesic mechanism of pulsed radiofrequency.Methods:A total of 140 adult male Sprague-Dawley(SD)rats were randomly divided into 7 groups(n=20 for each group): Sham,SNI,sham pulsed radiofrequency(SPRF)(SPRF),45-volt with pulsed radiofrequency(45VPRF),65-volt with pulsed radiofrequency(65VPRF),85-volt with pulsed radiofrequency(85VPRF),and 100-volt with pulsed radiofrequency(100VPRF).SNI model was exposed the left sciatic nerve,ligated and cut off the tibial nerve and common peroneal nerve and preserved the sural nerve of SD rat.The rats in 45 VPRF,65VPRF,85 VPRF and 100 VPRF groups were received different voltage PRF on left L5 DRG on day 7 after nerve injury respectively,While SPRF group rats were only put electrode adjacent to left L5 DRG without PRF on 7th day after SNI.The mechanical paw withdrawal threshold(MWT)was measured before SNI and on 1st,3rd,7th,8th,10 th,14th,21 st day after SNI.The expression levels of TNF-α and IL-10 in the spinal dorsal horn were measured by immunofluorescence and Western blot on 14 th and 21 st day after SNI,.Results: Compared with those in Sham group at the same time point,the MWTs and the expression leves of IL-10 in the dorsal horn of spinal cord were decreased,while the expression levels of TNF-α were upregulated in other six groups after SNI(P<0.01).Compared with those in the SNI group and the SPRF group,the MWTs in 45 VPRF group,65 VPRF group,85 VPRF group and 100 VPRF group were elevated from 8th day after SNI(P < 0.01).The expression levels of TNF-αwere decreased(P < 0.01),whereas the expression levels of IL-10 in the dorsal horn of spinal cord were upregulated in 45 VPRF group,65 VPRF group,85 VPRF group and 100 VPRF group(P<0.05)compared to those in the SNI group and the SPRF group.There was no significant difference in MWT,the levels of TNF-αand IL-10 in spinal dorsal horn between 45 VPRF group and 100 VPRF group(P>0.05).Compared with 45 VPRF group and 100 VPRF group,the MWTs were elevated from 12 th day after SNI(5th day after PRF)(P<0.01),TNF-α was decreased and IL-10 was upregulated in 65 VPRF group(P<0.05).The rising of MWT levels in 85 VPRF group were superior to those in 45 VPRF group,65 VPRF group and 100 VPRF after PRF treatment(P < 0.01),the changes of spinal descending TNF-α and ascending IL-10 levels were more remarkable in 85 VPRF group compared to other three groups(P<0.05).There were no significant differences in the MWT,TNF-αand IL-10 between SNI group and SPRF group(P>0.05).Conclusion: Different voltage PRF on DRG contributed to different reduction of neuropathic pain via regulation of the inflammatory in spinal dorsal horn.The 85 VPRF gained advantage over other voltage PRF,the profit of greater voltage than 85 V is not improved further.The results of this study suggest a theoretical basis for the clinical treatment of neuropathic pain by high voltage with PRF.