Intervention of electroacupuncture on phosphorylation of spinal ATF-2 at Thr71 site in rats with CFA-induced inflammatory pain

Objective: To observe the analgesic effect of electroacupuncture(EA) and its intervene on the activation of ATF-2 at Thr71 in spinal cord dorsal horn of rats.Methods: All rats were randomly divided into normal group(N group),model group(CFA group) and electroacupuncture group(EA group).Inflammatory pain model was established by injecting subcutaneously with 0.1ml Complete Freund's Adjuvant(CFA) into right hindpaw of rats in CFA and EA group.EA(dilatational wave,2/100Hz,1mA for 15 min,2mA for 15 min) was applied to bilateral 'Zusanli'(ST 36) and 'Kunlun'(BL 60) for 30min,once per day.The paw withdrawal thresholds(PWTs) were measured by using Dynamic Plantar Aesthesiometer 37450before CFA-injection(as Base) and at 1d,3d,14d after CFA-injection.The number of phospho-ATF-2(Thr71) positive cells in lumbar spinal cord dorsal horn(SCDH) were detected by immuno-histochemistry at 3d,14d after CFA-injection.Results: Compared with N group,PWTs of rats in CFA group were decreased markedly at 1d,3d,14d after CFA-injection(P0.05),and the number of p-ATF-2(Thr71) positive cells of ispilateral SCDH in CFA group began to increase at 3d post-injection(P0.01),maintained until 14d post-injection(P0.01).PWTs in EA group were higher obviously than those in CFA group at 3d,14d after CFA-injection(P0.01).Moreover,the numbers of p-ATF-2(Thr71) positive cells of ispilateral SCDH were significantly less than those in CFA group at same time point(P0.01).Conclusion: Inhibiting phosphorylation of ATF-2 at Thr71 site in SCDH of CFA rats maybe a new mechanism of EA analgesia.