Effect of transcutaneous electric nerve stimulation on GFAP and 5-HT positive staining cells in corresponding lumbar spinal cord in chronic compression of dorsal root ganglion in rats model and its relation with pain

Objective To research the effect of transcutaneous electric nerve stimulation(TENS) on the GFAP and 5-HT positive staining cells in corresponding lumbar spinal cord in rat model with chronic compression of dorsal root ganglion,and its correlation with pain. Methods Forty-two male Wistar rats were randomly divided into 3 groups:the normal control group(group A,n=6),the model group with chronic compression of the dorsal root ganglion(CCD)(group B,n=18),and the treated group with transcutaneous electric nerve stimulation in CCD model rats(group C,n=18).After determination of pain threshold once two days for two weeks,six rats with similar pain threshold separated from B and C group were strained immunohistochemically with two rats in group A.The rest rats(in groups A,B,C) were stained immunohistochemically at day 2 and week 1 after operation. Results ①The change of pain threshold,at day 2 after CCD,the pain threshold began to decrease,and was negatively correlated with postoperative time.Afte six days,pain threshold in group C increased more than in group B(P0.05);②Immunohistochemical results showed that at day 2,the expression of GFAP and 5-HT positive staining cells in groups B and C was higher than in group A(P0.05);at weeks 1 and 2,the expression of GFAP and 5-HT positive staining cells in group B increased groups A and C(P0.05),and there was no remarkable change in groups A and C. Conclusion The decrease of GFAP and 5-HT positive staining cell activation may be one of the mechanism for the TENS to alleviate the pain of CCD rats.And GFAP and 5-HT positive staining cells may have an activation interrelation.