[Effects of electroacupuncture on gait and proliferation and differentiation of muscle satellite cell in rats with acute blunt trauma of gastrocnemius muscle].

To observe the effects of electroacupuncture on threshold of pain, gait, proliferation and differentiation of muscle satellite cell in rats with acute blunt trauma of gastrocnemius muscle, and to explore the possible mechanism of electroacupuncture in promoting the repair of acute injury of skeletal muscle.A total of 48 SD rats were randomly divided into a blank group (6 rats), a model group (24 rats) and an electroacupuncture group (18 rats). In the model group and the electroacupuncture group, the model of acute blunt trauma of gastrocnemius muscle was established by self-made impactor. In the electroacupuncture group, electroacupuncture was applied at "Chengshan" (BL 57) and "Yanglingquan" (GB 34) on the right side, with disperse-dense wave, in frequency of 2 Hz/100 Hz, once a day, 30 min each time. Electroacupuncture intervention was performed for 3, 7 and 14 days according to the sampling time. On the 1st, 3rd, 7th and 14th days after modeling, the mechanical withdrawal pain threshold of hindfoot was detected by Von Frey method; the standing time and the maximum contact area of the right hindfoot were recorded by Cat Walk XTTM animal gait analysis instrument; the morphology of the right gastrocnemius muscle and the number of inflammatory cells were observed by HE staining; the positive expression of paired box gene 7 (Pax7) and myogenic differentiation (MyoD) of the right gastrocnemius muscle was detected by immunofluorescence.After modeling, the muscle fiber rupture and massive infiltration of red blood cells and inflammatory cells were observed in the right gastrocnemius muscle; after electroacupuncture intervention, the morphology of muscle fiber was intact and the infiltration of inflammatory cells was improved. Compared with the blank group, in the model group, the differences of mechanical withdrawal pain threshold between the left and right foot were increased (P<0.05), the standing time was shortened and the maximum contact area of the right hindfoot was decreased (P<0.05), the number of inflammatory cells and the positive expression of Pax7 and MyoD of the right gastrocnemius muscle were increased (P<0.05) on the 1st, 3rd, 7th and 14th days after modeling. Compared with the model group, in the electroacupuncture group, the differences of mechanical withdrawal pain threshold were decreased (P<0.05), the standing time was prolonged (P<0.05), the number of inflammatory cells of right gastrocnemius muscle was decreased (P<0.05) on the 7th and 14th days after modeling; the maximum contact area of the right hindfoot was increased (P<0.05), the positive expression of MyoD of the right gastrocnemius muscle was increased (P<0.05) on the 3rd, 7th and 14th days after modeling; the positive expression of Pax7 of the right gastrocnemius muscle was increased (P<0.05) on the 3rd day after modeling.Electroacupuncture can effectively improve the pain threshold and gait in rats with acute blunt trauma of gastrocnemius muscle, and promote the repair of skeletal muscle injury, the mechanism may be related to the up-regulation of Pax7 and MyoD, so as to promoting the proliferation and differentiation of muscle satellite cell.目的：观察电针对腓肠肌急性钝挫伤大鼠痛阈、步态及肌卫星细胞增殖分化的影响，探讨电针促进骨骼肌急性损伤修复的可能机制。方法：将48只SD大鼠随机分为空白组（6只）、模型组（24只）和电针组（18只）。模型组、电针组大鼠采用自制打击器建立右侧腓肠肌急性钝挫伤模型。电针组大鼠于右侧“承山”“阳陵泉”行电针干预，予疏密波，频率2 Hz/100 Hz，每次30 min，每日1次。按取材时间分别干预3、7、14 d。造模后第1、3、7、14天，采用Von Frey法检测各组大鼠后足机械缩足反射痛阈，计算左右足痛阈差值；Cat Walk XTTM动物步态分析仪记录大鼠站立时间及右后足最大接触面积；HE染色法观察大鼠右侧腓肠肌形态及炎性细胞数；免疫荧光法检测大鼠右侧腓肠肌配对盒基因7（Pax7）及成肌分化因子（MyoD）阳性表达。结果：造模后右侧腓肠肌肌纤维断裂，可见大量红细胞及炎性细胞浸润；电针干预后肌纤维组织形态完整，炎性细胞浸润明显减少。与空白组比较，模型组大鼠造模后第1、3、7、14天后足机械缩足反射痛阈差值升高（P<0.05），站立时间缩短、右后足最大接触面积减少（P<0.05），右侧腓肠肌炎性细胞数及Pax7、MyoD阳性表达增加（P<0.05）。与模型组比较，电针组大鼠造模后第7、14天后足机械缩足反射痛阈差值降低、站立时间延长（P<0.05），右侧腓肠肌炎性细胞数减少（P<0.05）；造模后第3、7、14天右后足最大接触面积增大、右侧腓肠肌MyoD阳性表达增加（P<0.05）；造模后第3天右侧腓肠肌Pax7阳性表达增加（P<0.05）。结论：电针可有效改善腓肠肌急性钝挫伤大鼠痛阈及步态，促进骨骼肌损伤修复，其机制可能与增加Pax7、MyoD表达，从而促进肌卫星细胞增殖分化有关。.