Objectives: To observe the effects of electroacupuncture (EA) at "Jiaji" (EX-B 2) combined with neurodynamic mobilization (NM) on the cross-sectional area of the gastrocnemius muscle fibers after sciatic nerve injury in rabbits, and the expression of nuclear factor κB (NF-κB) and muscle-specific ring-finger protein 1 (MuRF1).
Methods: A total of 180 common-grade New Zealand rabbits (half male and half female) were randomly divided into five groups, i.e. a normal control group, a model control group, a NM group, an EA group and a combined intervention group, 36 rabbits in each group. Except in the normal control group, clipping method was used to prepare the model of sciatic nerve injury in the rest groups. On the 3rd day of successful modeling, NM was delivered in the NM group. In the EA group, EA was exerted at bilateral "Jiaji" (EX-B 2) of L4 to L6, stimulated with disperse-dense wave and the frequency of 2 Hz/100 Hz. In the combined intervention group, after EA delivered at bilateral "Jiaji" (EX-B 2) of L4 to L6 , NM was operated. The intervention in each group was delivered once daily, for 6 days a week, and lasted 1, 2 or 4 weeks according to the collection time of sample tissue. After 1, 2 and 4 weeks of intervention, in each group, the toe tension reflex score and the modified Tarlov test score were observed; the morphology of the gastrocnemius muscle was observed by HE staining and the cross-sectional area of muscular fiber was measured; using Western blot method, the expression of NF-κB and MuRF1 of the gastrocnemius muscle was detected.
Results: After 1, 2 and 4 weeks of intervention, the toe tension reflex scores and the modified Tarlov scores in the model control group were lower than those of the normal control group (P<0.05), and these two scores in the NM group, the EA group and the combined intervention group were all higher than those of the model control group (P<0.05); the scores in the combined intervention group were higher than those in the EA group and the NM group (P<0.05). The gastrocnemius fibers were well arranged and the myocyte morphology was normal in the normal control group. In the model control group, the gastrocnemius fibers were disarranged, the myocytes were irregular in morphology and the inflammatory cells were infiltrated in the local. In the NM group, the EA group and the combined intervention group, the muscle fibers were regularly arranged when compared with the model control group. After 1, 2 and 4 weeks of intervention, the cross-sectional areas of the gastrocnemius muscle fibers in the model control group were smaller than those of the normal control group (P<0.05). The cross-sectional areas in the NM group, the EA group and the combined intervention group were larger than those of the model control group (P<0.05), and the cross-sectional areas in the combined intervention group were larger than those in the NM group and the EA group (P<0.05). After intervention for 1, 2 and 4 weeks, the protein expressions of NF-κB and MuRF1 in the gastrocnemius muscle were higher in the model control group in comparison of those in the normal control group (P<0.05). In the NM group, the EA group and the combined intervention group, the expressions of NF-κB after intervention for 1, 2 and 4 weeks and the expressions of MuRF1 after 2 and 4 weeks of intervention were lower when compared with those in the model control group (P<0.05). In the combined intervention group, the protein expressions of NF-κB after intervention for 1, 2 and 4 weeks and the expressions of MuRF1 after 2 and 4 weeks of intervention were decreased when compared with those in the NM group and the EA group (P<0.05).
Conclusions: Electroacupuncture at "Jiaji" (EX-B 2) combined with NM may increase the muscle strength and sciatic function and alleviate gastrocnemius muscle atrophy in the rabbits with sciatic nerve injury. The underlying mechanism is related to the inhibition of NF-κB and MuRF1 expression.
目的: 观察电针“夹脊”结合神经松动术对兔坐骨神经损伤后腓肠肌肌纤维横截面积及核因子κB（NF-κB）、肌肉特异性环指蛋白1（MuRF1）表达的影响。方法: 将180只普通级新西兰大耳兔（雌雄各半）随机分为正常对照组、模型对照组、神经松动术组、夹脊电针组、结合组5组，各36只。除正常对照组外，其余4组采用钳夹术制备坐骨神经损伤模型。造模成功后第3天，神经松动术组予神经松动术治疗；夹脊电针组于双侧L4-L6“夹脊”行电针干预，疏密波，频率2 Hz/100 Hz；结合组先电针双侧L4-L6“夹脊”，再予神经松动术干预。均每日1次，每周6 d，按取材时间分别干预1、2、4周。干预1、2、4周后，观察各组兔趾张反射及改良Tarlov评分；HE染色法观察各组兔腓肠肌形态，并测定肌纤维横截面积；Western blot法检测各组兔腓肠肌NF-κB、MuRF1蛋白表达。结果: 干预1、2、4周后，模型对照组兔趾张反射和改良Tarlov评分低于正常对照组（P<0.05）；神经松动术组、夹脊电针组、结合组兔趾张反射和改良Tarlov评分高于模型对照组（P<0.05）；结合组兔趾张反射和改良Tarlov评分高于夹脊电针组、神经松动术组（P<0.05）。正常对照组腓肠肌肌纤维排列整齐、肌细胞形态正常；模型对照组腓肠肌肌纤维排列紊乱、肌细胞形态不规则，局部炎性细胞浸润；神经松动术组、夹脊电针组、结合组腓肠肌肌纤维形态较模型对照组规则。干预1、2、4周后，模型对照组腓肠肌肌纤维横截面积小于正常对照组（P<0.05）；神经松动术组、夹脊电针组、结合组腓肠肌肌纤维横截面积大于模型对照组（P<0.05）；结合组腓肠肌肌纤维横截面积大于神经松动术组、夹脊电针组（P<0.05）。干预1、2、4周后，模型对照组腓肠肌NF-κB、MuRF1蛋白表达高于正常对照组（P<0.05）；神经松动术组、夹脊电针组和结合组干预1、2、4周后NF-κB蛋白表达及干预2、4周后MuRF1蛋白表达低于模型对照组（P<0.05）；结合组干预1、2、4周后NF-κB蛋白表达及干预2、4周后MuRF1蛋白表达低于神经松动术组和夹脊电针组（P<0.05）。结论: 电针“夹脊”结合神经松动术可改善坐骨神经损伤兔肌肉力量、坐骨神经功能及腓肠肌萎缩，其机制可能与抑制NF-κB、MuRF1表达有关。.
Keywords: Point EX-B 2 (Jiaji); electroacupuncture; gastrocnemius muscle atrophy; muscle-specific ring-finger protein 1 (MuRF1); neurodynamic mobilization; nuclear factor κB (NF-κB); sciatic nerve injury.