| Aging is result in the degradation of the structure and function of skeletal muscle, and most of the researches believed that it is closely related to the age-related accumulation of reactive oxygen species(ROS) in skeletal muscle cell. While Sirtuin3(Sirt3) is the acetylation enzyme to which positioned in the mitochondrion of the cell and bound up with cellular energy metabolism and oxidative stress. It had been proved to be correlated with the human longevity. Recent studies have shown that Sirt3 act as a downstream target gene of peroxisome proliferators activated receptor-gamma coactivator 1 α(PGC-1α), can have an effect on the generation of ROS and mitochondrial biogenesis through mediating the later. As an important intervention approach, sports exercises can mitigate intervention of age-related muscle atrophy, there are many researches on it in recent years, and opinions also vary on the exact molecular mechanism. This study was conducted to investigate the effects of treadmill exercise on mitochondria Sirt3 in gastrocnemius muscle of aging rats and PGC-1α protein levels, and explore the molecular mechanisms of sports exercises mitigating intervention of age-related muscle atrophy..Methods :20 male SD rats were randomly divided into control group(CG) and exercise group(EG) with 10 rats in each group. The groups EG underwent treadmill training at 15m/min, 5% grad, and 30 min per day in the first week and add 5min per week in the rest of the three weeks and 6 days per week. All rats were sampled after 24 h after 4-week running. Observe the crosscut slice of aging rats’ gastrocnemius muscle by light microscope. The contents of Mn-SOD and MDA of skeletal muscle cell were observed by ultraviolet spectrophotometry, the content of 8OHd G was observed by ELISA, and the contents of Sirt3 and PGC1-α were observed by Western Blot.Results :(1) Observation of gastrocnemius muscle crosscut slice: it can be observed that the gastrocnemius muscle cells are loose, irregular arrangement and other characteristics, the nucleus increased obviously, increasing and shifting in the control group; and the cells are VI arranged more regularly, the nucleus are located in the edge of the cell, and can be observed the tend of skeletal muscle change from polygon to circular; the percentage of gastrocnemius muscle cross-sectional area taken by occupied section area of control group is lower than that of the exercise group.(2) Oxidative stress of gastrocnemius muscle cells: The activity of Mn-SOD of the exercise group is higher than the control group(P<0.01); and the contents of the MDA(P<0.05) and 8OHd G(P<0.01) of the exercise group decreased compared with the control group.(3) The protein contents of Sirt3 and PGC1-α in gastrocnemius muscle: The protein contents of Sirt3 and PGC1-α in gastrocnemius muscle are increased after 4-week running(P<0.01).Conclusion:(1) Treadmill exercise can improve the muscle Sirt3 protein content of aging rats, and increase the activity of Mn-SOD, increase the gastrocnemius ROS scavenging ability, decrease he oxidative damage of the gastrocnemius muscle in the aging process, and to delay age-related skeletal muscle atrophy, ensure the relatively complete of its structure and function.(2) Treadmill exercise can increase the activity of Mn-SOD, and reduce MDA and 8OHd G at the same time. It can be shown to the ROS of the cells decreased. The anti-oxidative stress capacity increased. And the decreased of the 8OHd G is a proof of the exercise intervention to oxidative damage of DNA declined, and then explains that the exercise intervention reduced oxidative damage of mitochondrion.(3) Treadmill exercise can increase the content of PGC1-α., PGC1-α could increase Sirt3 protein expression. And both of them can inhibit the production of ROS, thereby protecting skeletal muscle from oxidative damage, which is also one of the molecular mechanisms of sports exercises mitigating intervention of age-related muscle atrophy. |
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