Effects Of Exercise On Skeletal Muscle Oxidative Stress And Autophagy-related Genes Expression

When internal oxidative system fails to remove a large number of free radicals, the balance between oxidative system and antioxidative system will be changed, free radicals may be gathered and oxidative stress can come in to being. Oxidative stress can lead to mitochondrial DNA damage, lipid oxidation, reduction of ATP and Ca2+, engorgement, and eventually lead to mitochondrial damage. Mitochondrial damage can bring up autophagy, autophagic cell death, apoptosis and necrosis.Autophagy is a vital basic phenomenon that widely exists in eukaryotic cells, its mail function is to degrade a bulk of misfolded or damaged proteins and organelles, and eventually make sure that cell can renew and recycle the protein and organelles by itself. Autophagy is not only taking part in programmed cell death, innate immunity, growth, differentiation, but also the pathogenesis of tumor, neurodegenerative diseases, cardiovascular diseases and aging. When suffering exercise induction, lack of energy, injury and oxidative stress, autophagy will be upregulated. Autophagy-related genes are very special to autophagy, about30autophagy related genes were identified currently, among them, Atg7, Atg9, Beclinl and LC-3are exceedingly important to the activation of autophagy.Recently, molecular signaling mechanism of skeletal muscle autophagy is increasingly known to us, finding the relations between oxidative stress and autophagy of muscle via exercise training will offer us a theoretical basis about how to prevent or cure autophagy-related diseases as well as how to arrange our exercise training.Purpose:Via sitting up different phase model of incremental load exercises as well as their recovery stage, measured the concentration of MDA, SOD and H2O2with the microplate reader to compared with each group, and measured the mice gastrocnemius Atg7, Atg9, Beclinl as well as LC-3mRNA levels with Real-time PCR, we increasingly want to find the relations between oxidative stress and skeletal muscle autophagy after incremental load exercises, and know how incremental load exercises to affect muscle autophagy. Eventually, we hope that we can find a suitable intensity and time to moderate the level of autophagy and give us a theoretical basis to arrange our exercise training.Methods:80male ICR mice(7-8weeks old, weight19-21g) were randomly divided into Control group(R, n=8), Incremental load exercises for45min group(E45, n=8), Incremental load exercises for90min group(E9o, n=8), Incremental load exercises for120min group(E120, n=8), Incremental load exercises for150min group(E150, n=8), Recovery for3h after incremental load exercises group(ER3, n=8), Recovery for6h after incremental load exercises group(ER6, n=8), Recovery for12h after incremental load exercises group(ER12, n=8), Recovery for18h after incremental load exercises group(ER18, n=8), Recovery for24h after incremental load exercises group(ER24, n=8). Three days adaptive treadmill training before formal treadmill training(O°,0.8km/h,5min), Intensity and time of formal treadmill training are as follows:The first load:lkm/h,15min; The second load:1.2km/h,15min; The third load:1.3-1.5km/h. measured the concentration of MDA, SOD and H2O2with the microplate reader to compared with each group, and measured the mice skeletal muscle Atg7, Atg9, Beclinl as well as LC-3mRNA levels with Real-time PCR.Results:①The concentration of MDA and H2O2in skeletal muscle both reach a very high level in the early stage of incremental load exercises, and then begin to reduce until the exercises are over. In the recovery stage after incremental load exercises, the concentration of MDA and H2O2in skeletal muscle firstly maintains this low level, and then start to rise.②The concentration of SOD in skeletal muscle reach a very low level in the early stage of incremental load exercises, and then begin to rise until the exercise is over. In the recovery stage after incremental load exercises, the concentration of SOD in skeletal muscle firstly rise a higher level, and then start to drop,③The skeletal muscle Atg7, Atg9, Beclinl as well as LC-3mRNA levels in the early stage of incremental load exercises rise quickly and reach a highest level, but in the late stage of incremental load exercises they begin to drop.④Although the skeletal muscle Atg7, Atg9, Beclinl as well as LC-3mRNA levels maintain a low level in the early recovery stage after incremental load exercises, yet they are rising all the time. Until the late recovery stage after incremental load exercises they maintain the stable levels.Conclusion:①The level of oxidative stress in skeletal muscle firstly reaches a highest level in the early stage of incremental load exercises, and then begins to drop until the exercises are over. In the recovery stage after incremental load exercises, The level of oxidative stress in skeletal muscle firstly firstly maintains this low level, and then start to rise a stable level.②Skeletal muscle autophagy in the early stage of incremental load exercises rises a lot and maintains a highest level, and the begin to drop.③Although skeletal muscle autophagy in the early recovery stage after incremental load exercises maintains a low level, yet it’s rising all the time, unitl the late recovery stage after incremental load exercises, skeletal muscle autophagy maintains a stable level.④The different changes of skeletal muscle autophagy are attributed to the changes of skeletal muscle oxidative stress.