耐力运动促进骨骼肌卫星细胞线粒体能量代谢及其对成肌分化的影响

Endurance Exercise Promotes Mitochondrial Bioenergetic Metabolism in Muscle Satellite Cells and Its Effect on the Myogenic Differentiation

目的:观察耐力运动训练对骨骼肌卫星细胞线粒体能量代谢的影响,并探讨其对成肌分化的调控机制。方法:C57BL/6小鼠随机分为安静对照组(N组)和运动训练组(T组)。12周训练后,两步酶消化法分离骨骼肌卫星细胞,免疫化学染色鉴定卫星细胞纯度。原代培养并体外诱导成肌分化,倒置显微镜观察卫星细胞成肌分化程度。分别在分化0 h和24 h测定线粒体呼吸功能、ATP合成活力、膜电位和MyHC、COXⅣ、AMPK、p-AMPK、p21蛋白表达量。结果 :免疫化学染色显示desmin阳性细胞>90%,表明获取的卫星细胞纯度高。HE染色结果显示T组腓肠肌肌纤维横截面积显著高于N组(P<0.05)。分化0 h时,T组态3呼吸速率(ST3)、呼吸控制比(RCR)、线粒体ATP合成活力、p21表达较N组显著升高(P<0.05),p-AMPK表达显著降低(P<0.05)。分化24 h时,T组肌管形成数量及MyHC表达较N组显著升高(P<0.05),ST3、RCR、ATP合成活力、膜电位、p21及COXⅣ表达显著增加(P<0.05),p-AMPK表达显著降低(P<0.05)。结论:耐力运动训练可提高未分化卫星细胞线粒体能量代谢水平,继而抑制AMPK活化而增加p21表达,从而促进成肌分化的启动和进程。

Objective To observe the effect of endurance exercise on the mitochondrial bioenergetic metabolism in skeletal muscle satellite cells and its effect on the myogenesis. Methods C57BL/6 mice were randomly divided into two groups： normal control group （N） and exercise training group （T）. The animals in group T exercised on a treadmill for 12 weeks. Purified satellite cells were obtained and im- munohistochemical staining was employed to identify the satellite cells cultured in vitro. Differentiation was induced by changing the growth medium and observed by inverted microscopy. At 0 and 24 h of differentiation,mitochondrial respiration parameters,ATP synthetase activity,mitochondrial membrane potential （A~）,MyHC, COXIV ,AMPK, p-AMPK, and p21 protein expression were measured. Results Comparing with group N, at 0 h of differentiation, ST3, RCR, ATP synthesis activity, and p21 protein ex- pression dramatically increased（P 〈 0.05）, and p-AMPK protein expression significantly decreased（P 〈 0.05） in group T. At 24 h of differentiation, comparing with group N, the formation of myotubes and ex- pression of MyHC markedly increased in group T （P 〈 0.05）. In addition,ST3,RCR,and ATP synthesis activities, A~,p21 ,and COX IV protein expression showed significantly enhanced （P 〈 0.05）,and p- AMPK protein expression significantly diminished （P 〈 0.05）. Conclusion Endurance exercise markedly promotes the mitochondrial bioenergetic metabolism,which in turn enhances the myogenic differentiation through inactivation of AMPK and up-regulation of p21.