白藜芦醇对老年大鼠骨骼肌力量及肌原纤维结构的影响

摘要

目的 观察白藜芦醇对老年大鼠骨骼肌质量、抓力、肌原纤维超微结构以及AMPK/sirt1通路的影响.方法20只25月龄SD大鼠随机分为老年对照组(OC组,10只)和老年白藜芦醇组(OR组,10只),另外10只6月龄SD大鼠作为青年对照组(YC组).OR组给予连续6周白藜芦醇干预.电子抓力仪测量大鼠前肢抓力,分析天平称量大鼠腓肠肌质量,用腓肠肌质量(mg)/体质量(g)得出肌肉减少症指数(SI),透射电子显微镜观察大鼠肌原纤维肌小节、明带、暗带以及H带长度的改变.Western blot方法检测AMPK、P-AMPK、sirt1的蛋白表达量.结果 OC组腓肠肌SI值低于YC组(P<0.05),抓力低于YC组(P<0.05),肌小节长度、暗带长度、明带长度和H带长度均高于YC组(P<0.05),AMPK、P-AMPK、sirt1的蛋白表达量均低于YC组(P<0.05);与OC组相比,OR组SI值未见显著性差异(P>0.05),抓力升高(P<0.05),肌小节长度、明带长度和H带长度均降低(P<0.05),暗带长度未见统计学差异(P>0.05),P-AMPK、sirt1的蛋白表达量均显著增高(P<0.05).结论 白藜芦醇不能减缓肌肉质量的减少,但是可以增加老年大鼠的抓力.这种作用可能跟白藜芦醇激活AMPK/sirt1通路,改善肌原纤维结构的老化有关.%Objective To observe the effect of resveratrol on muscle mass,forelimb grip strength,myofibril structure and AMPK/sirt1 pathway in skeletal muscles of aged rats. Methods Twenty aged (25 months old) SD rats were randomly divided into aged control group and resveratrol treatment group(10 in each group)with 10 young(6 months old)rats served as the young control group. In resveratrol treatment group, the rats were treated with resveratrol (mixed in chow) for 6 weeks.After the treatment, the mass of the gastrocnemius was measured and the sarcopenia index (SI) was calculated as the gastrocnemius mass(mg)to body weight(g)ratio.The forelimb grip strength of the rats was measured using a electronic grip strength meter, and the lengths of the sarcomere, I-band, A-band and H-zone of the myofibrils were determined by transmission electron microscopy.Results Compared with the young rats,the aged control rats had significantly lower SI of the gastrocnemius(P<0.05) and grip strength (P<0.05) with increased lengths of the sarcomere, A-band, I-band and H-zone (P<0.05) and lowered expressions of AMPK, P-AMPK, and sirt1 protein (P<0.05). Resveratrol treatment of the aged rats significantly increased the forelimb grip strength, reduced the lengths of sarcomere length, I-band and H-zone (P<0.05) and increased, P-AMPK, sirt1 protein expressions (P<0.05) without significantly affecting the SI (P>0.05) or the A-band length (P>0.05). Conclusion Resveratrol does not improve the muscle mass but can increase the forelimb grip strength in aged rats possibly by activating AMPK/sirt1 pathway to improve the ultrastructure of the myofibrils.