| [Objective]To observe the changes in pain response after the application of pulsed radiofrequency(PRF)at the ligation site of the sciatic nerve branches in a spared nerve injury(SNI)model in rats and investigate the effect of PRF on the expression of Nuclear Factor-?B(NF-?B),Tumor Necrosis Factor-a(TNF-a),Interleukin-6(IL-6)in the Dorsal Root Ganglion(DRG),then we can try to explore the neuro-inflammation mechanism about the therapeutic effect of PRF in neuropathic pain.[Method]1 SubjectEighteen adult male Sprague-Dawley rats(weighing 200-250 g)were randomly divided into 3 groups:Sham group,SNI group and SNI+PRF group.Each group contains six rats.2 Model and OperationIn addition to the Sham group,the other groups were cut and ligatured the tibial and common peroneal nerves leaving the remaining sural nerve intact to build rat spared nerve injury model.Only Sham group exposure the three terminal branches of the sciatic nerve without any lesion.On the day 7 after surgery,PRF treatment was applied at the proximal ligation site of the sciatic nerve branches in the SNI+PRF group.The other groups received no treatment.Four rats of each group were randomly chosen to be tested by Western Blotting on the day 8 after surgery.The dorsal root ganglions of total 16 rats were cut off after pain behaviors were tested.3 Evaluation indexAll rats were evaluated for sensitivity to mechanical stimulation with von frey filaments and to cold stimulation with a temperature testing apparatus at various time points.The 50%Paw Withdrawal Mechanical Threshold(PWMT)and cold-plate cumulative duration of hindpaw withdrawals were measured as pain-related behaviors on the 2 h before operation,and 1,4,7,8 d after operation.Western Blotting was used to detect the expression of NF-?B,TNF-?,IL-6 in the dorsal root ganglion after the last pain behavior test.[Results]1 50%Paw Withdrawal Mechanical Threshold(PWMT)There were no significantly differences between PMWT in the left hind paws of all rats before the operation(P>0.05).On the 1,4,7 d after surgery,the PMWT was significantly,gradually reduced in SNI group and SNI+PRF group when compared with Sham group(P<0.05),and there were no significantly differences between SNI group and SNI+PRF group(P>0.05).On the 8 d after operation(also the 24 h after PRF),the PMWT was significantly increased in SNI+PRF group than SNI group(P<0.05),and the PMWT was continuing to decline in SNI group when compared with Sham group(P<0.05).2 Cold-plate cumulative duration of hindpaw withdrawalsThere were no significantly differences between cumulative duration of hindpaw withdrawals in the left hind paws of all rats before the operation(P>0.05).On the 1,4,7 d after operation,the cumulative duration of hindpaw withdrawals in SNI group and SNI+PRF group was significantly,gradually increased compared to Sham group(P<0.05),and there were no significantly differences between SNI group and SNI+PRF group(P>0.05).On the 8 d after surgery(also 24 h after PRF treatment),the cumulative duration of hindpaw withdrawals was significantly decreased in SNI+PRF group than SNI group(P<0.05),and the cumulative duration of hindpaw withdrawals was significantly continuing increased in SNI group when compared with Sham group(P<0.05).3 Results of Western BlottingOn the 8 d after surgery,the SNI group had significantly higher expression levels of NF-?B,TNF-? and IL-6 than the other groups(P<0.05).The expression levels of TNF-a and IL-6 was significantly higher in SNI+PRF group when compared with Sham group(P<0.05),but the expression levels of NF-?B had no significantly differences between these groups(P>0.05).SNI+PRF group had significantly lower expression levels of NF-?B,TNF-a and IL-6 than SNI group(P<0.05).[Conclusions]The changes in pain behavior of SNI rats related to the activation of NF-?B and release of its downstream inflammatory cytokine(TNF-a and IL-6)in the dorsal root ganglion.After 24 h PRF treatment,the pain response of SNI rats was significantly decreased.The underlying mechanism of PRF may be the regulation of neuro-inflammation that influenced the expression levels of NF-?B,TNF-a and IL-6. |
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