Researching In Influence Of Effects Of Pulsed Radiofrequencey On Sodium Channels Nav1.8in A Rat Model Of Neuropathic Pain

Objective:To observe the mechano allodynia changes and dynamicexpression of Nav1.8in the dorsal root ganglion(DRG) of rats with spared nerveinjury(SNI) of sciatic nerve after pulsed radiofrequency,and to investigate theexpression of Nav1.8in DRG, and to reveal the mechanism of pulsedradiofrequency on neuropathic pain.Methods: Forty male SD rats were randomly divided into five group（n=8）after establishing SNI model:Control group（N group），spared nerve injurygroup（S group），spared nerve injury sham group（SS group），pulsedradiofrequency group（P group），pulsed radiofrequency sham group（PSgroup）,following measured the change of pain threshold。S group wereunderwent spared nerve injury of sciatic nerve;in SS group were exposed sparednerve of sciatic nerve but non-deligation; on the7th SNI surgery postoperativeday, in P group, PRF was delivered at42℃with a pulse duration of20ms(500kHz) and pulse rate of2Hz to the proximal sciatic nerve for5min; in PSgroup, PRF needles were placed in the proximal sciatic nerve at ipsilateral for120seconds without radiofrequency current. Pain behavioral changes weremeasured before SNI operation,2～7postoperative day, and1～7days afterPRF treatment, respectively.then all of the rats were sacrificed after pain behavioral changes measuring for their DRG.The expression of Nav1.8on DRGwas measured by using Western Blot method.Results: Pain behavioral changes results:in before SNI operative day, there wereno significant difference compared with all groups.On2th post-SNI day,compared with N group,mechanical withdrawal threshold of S group, PS groupand P group were lower obviously (P＜0.05）；SS group was no significantdifference compared with N group. On7th post-SNI day, compared with Ngroup,mechanical withdrawal threshold of S group, PS group and P group werelower obviously (P＜0.05）；SS group was no significant difference comparedwith N group. On2th post-PRF day,compared with S group,PSgroup,mechanical withdrawal threshold of P group were increasedsignificantly(P＜0.05);P group was no significant difference compared with Ngroup,SS group（P＞0.05）. On7th post-PRF day,compared with S group,PSgroup,mechanical withdrawal threshold of P group were increasedsignificantly(P＜0.05);P group was no significant difference compared with Ngroup,SS group（P＞0.05）.Result of the Western Blot,the expression of Nav1.8in the DRG neurons in S group and PS group were significantly lower than Ngroup (P <0.05);compared with N group,P group expression decreasing (P <0.05), there was no significant difference in SS group（P＞0.05）.there was nosignificant difference between P group and S goup（P＞0.05）.Conclusion:PRF can increase the tactile allodynia threshold of SNI model,PRF is effective for the relief of tactile allodynia. the expression of Nav1.8inthe DRG neurons was no change in SNI model by PRF procedure on theipsilateral DRG.