[Effects of Electroacupuncture on Activities of Satellite Glial Cells of Dorsal Root Ganglia in Rats with Neck Incision Pain]. 2017
OBJECTIVE To observe the effect of electroacupuncture (EA) stimulation of "Futu"(LI 18), etc. on activities of satellite glial cells (SGCs) in the dorsal root ganglia (DRG) in rats with neck-incision pain so as to explore its mechanism underlying reduction of post-surgical pain of thyroidectomy. METHODS Male SD rats were randomly divided into control, model, EA-Futu (LI 18), EA-Hegu (LI 4)-Neiguan (PC 6), and EA-Zusanli (ST 36)-Yanglingquan (GB 34) groups, with 20 rats in each group. The neck-incision pain model was established by making a longitudinal incision and repeated mechanical stimulation. In the EA-LI 18, EA-LI 4-PC 6 and EA-ST 36-GB 34 groups, EA stimulation was administrated for 30 min, once a day,continuously for 3 days. The thermal pain threshold (PT) of the neck-incision region was detected. The immunoactivity of glial fibrillary acidic protein (GFAP,a specific marker for SGCs) and connexin 43 (Cx 43) of DRGs (C 2-C 6) was determined by fluorescent immunohistochemistry. The expression levels of GFAP, IL-1 β, IL-6, and TNF-α mRNAs were determined by quantitative Real-time PCR, and the contents of IL-1 β,IL-6,TNF-α assayed by enzyme linked immunosorbent assay (ELISA) and the expression of Cx 43 protein was detected by Western blot. RESULTS After EA intervention at LI 18 and LI 4-PC 6 (but not ST 36-GB 34), neck incision-induced reduction of the thermal PT was obviously prolonged in comparison with the model group (P<0.05),suggesting a pain relief. The expression levels of GFAP, IL-1 β, IL-6 and TNF-α mRNAs and Cx 43 protein, and the contents of IL-1 β, IL-6 and TNF-α in C 2-C 6 DRGs were all significantly up-regulated in the model group relevant to those of the control group (P<0.05). Following EA, modeling induced dramatic increase of expression of GFAP, IL-1 β, IL-6 and TNF-α mRNAs and Cx 43 protein in both EA-LI 18 and EA-LI 4-PC 6 groups, and the contents of IL-1 β and TNF-α in the EA-LI 18 group, IL-6 in the EA-LI 4-PC 6 group was considerably down-regulated (P<0.05). In comparison with the model group, no significant changes were found in all the abovementioned indexes of EA-ST 36 -GB 34 group except the down-regulated IL-1 β and TNF-α mRNAs, in the contents of IL-1 β and TNF-α of the EA-LI 4-PC 6 group, and in the IL-6 content of the EA-LI 18 group (P>0.05). CONCLUSIONS EA stimulation of LI 18 and LI 4-PC 6 can significantly suppress pain reaction of neck incision in the rat, which is closely associated with its effects in down-regulating the activity of SGCs, decreasing the release of pro-inflammatory cytokines and in weakening the expression of Cx 43 in the cervical DRGs.