The Investigation Of Effect Of Endurance Exercise On Mitochondrial Function And Autophagy Related Genes Of Ageing Mice Skeletal Muscle

Objective: Aging is a inevitably physiological processes. Studying of the mechanismof aging is conducive to maintain body functions and extend the human life.Mitochondria as the energy house of the cell, is the vital for the cell functionmaintaining. When the mitochondria dysfunction, human body’s function will beaffected by abnormal working of tissues and organ which are induced by the lossfunction of the cells, such as aging, cancer and others. As lots of studying shows,autophagy is a cell protection mechanisms under starvation or stress. Mitophagy as aspecial autophagy that removes the dysfunction mitochondria and avoids apoptosis ornecrosis. Studies have reported that mitochondrial autophagy involved in erythroidmaturation, neurodegenerative disease process in vivo. In this study,15-month-oldaging mouse skeletal muscle mitochondrial energetics, autophagy and mitophagywere detected after endurance exercise. Taking these results, we further explore themechanism of how sports affecting mitochondrial function, autophagy and mitophagyin the aging mice, and find some way to anti-aging.Method:20male6-8-weeks C57BL/6mice are randomly divided into quite group (C)and exercise group (E),10of each group. The mice are took8-weeks endurancetreadmill training, five days a week, forty minutes a day and twelve meter per minute(75%V O2max), when they are13-months old. The mice are sacrificed at the24hours after the last training.1) Isolated the gastrocnemius and purified themitochondria, we assay the mitochondrial respiratory state3(S3), state4(S4) andrespiratory control ratio (RCR) with the Clark oxygen electrode. The synthesis rate ofmitochondrial ATP enzyme is detected by luciferin-luciferase enzyme. At the same time, we assay the mitochondrial membrane potential and ROS genetation rate withfluorescence spectrophotometer.2) The transcriptional mRNA level of Beclin1、Bcl-2、Bax、Bnip3、Nix and HIF-1α are detected by real-time PCR.3) The proteinslevel of Beclin1, BCL-2and Bax are detected by Western-blotting.Results:1) There was no obvious weight changing after the endurance treadmilltraining between control and exercise group.2) Compared to the group C, the mitochondrial respiratory state3, state4, RCR andthe synthesis of ATPase of the group E was significantly higher（P<0.05，P<0.05，P<0.01，P<0.05respectively）.3) Mitochondrial membrane potential of the group E increased obviously with thegroup C (P<0.05).4) The ROS generation rate was lower in the group E compared with the group C(P<0.05).5) Compared to the group C, the transcriptional and translational level of Beclin1reduced dramatically in the group E（P<0.05，P<0.01respectively）, but it was incontrast to Bcl-2（P<0.01，P<0.05respectively）.6）Compared to the group C, the transcriptional and translational level of Bax did notchange significantly in the group E, but the protein ratio of Bcl-2/Bax increasedobviously in group E(P<0.01).7) Compared to the group C, the mRNA level of Bnip3and Nix did not changesignificantly in the group E.8) The transcriptional level of HIF-1α was no obvious changing also between thegroup C and E.Conclusions:1) The8weeks of aerobic treadmil exercise significantly improvemitochondria function and MP in aging mouse skeletal muscle;2) we speculate thatthe8weeks of aerobic treadmill exercise reduce the generation of ROS whichdecreases the level of autophagy;3) enhanced adaptation of mitochondiral functionmay be the reason that mitophagy has not been affected after the8weeks of aerobictreadmill exercise.