Effect of Endurance Training on Lipid-droplet Metabolism in Skeletal Muscle of Aging C57/Bl6J Mouse
|Tutor||LuJian; Bret H. Goodpaster|
|School||East China Normal University|
|Course||Human Movement Science|
|Keywords||Lipid droplet Natural aging mouse Sarcopenia Endurance exercisesMitochondria Protein anabolism signaling pathway|
PurposeLoss of skeletal muscle and strength usually accompany lipid droplet depot in skeletal muscle. IMTG can lead to insulin resistance, also interfere function of skeletal muscle. It is unknown how IMTG induce loss of skeletal muscle and strength. Exercise can improve skeletal muscle with attenuation IMTG. The present study is designed to determine the effects of treadmill running exercise on lipid droplet, mitochondria and IGF/Akt/mTOR signaling pathway in skeletal muscles C57BL6J after3weeks of exercise training to better understand the cellular and molecular mechanism between Sarcopenia and lipid metabolism.Methods:The study selects male C57BL6J at different month’s age as the research animal. The model of natural aging mouse is used, treadmill running exercise are used to intervene the aging model after3weeks for2-month and24-month respectively. DEXA method is used to detect Lean body mass and body fat mass of mice; Quantitative Real-time PCR and Western blotting method is used to detect ADRP, OXPAT, ATGL, HSL, DGAT, PGC-1α, Mfn2,Drp1, AMPK, ACC2, IGF-1, Akt, mTOR, PP2A in skeletal muscle.Results:1) Body fat mass increase, lean body mass decreases on the trend in old group,3weeks endurance exercise not improve body composition in old and young group.2) Lipid droplet relative protein involved two-way adjustment lipid drops function, the dynamic balance of anabolism and catabolism of lipid droplet is tendency to catabolism in skeletal muscle during aging process. Mitochondria biogenesis reduced, the dynamic balance of mitochondrial fusion and fission trend to fission leading to increasing mitochondria dysfunction. Fatty acid oxidation does not rely on AMPK/ACC2.3) During aging process, the dynamic balance of protein anabolism and catabolism trends to catabolism, result to loss muscle mass. The expression of PP2A gene and protein increase to interference IGF/Akt/mTOR signaling pathway.4) Three weeks intervene of treadmill running up-regulate OXPAT mRNA expression that can increase fatty acid oxidation. The gene expression of ADRP has does-dependent exercise during. UP-regulate genes of ATGL and HSL can induce lipid catabolism.5) There weeks treadmill running increase mitochondria biogenesis; there is no effect on mitochondrial fusion and fission and AMPK/ACC2in skeletal muscle of old and young group6) There weeks treadmill running prevent the gene PP2A in skeletal muscle in old group, it can remit that aging impair the skeletal muscle protein anabolism.Conclusion:1) Mice acquire more body fat in old group.2) During aging process, the dynamic balance of anabolism and catabolism of lipid droplet is tendency to anabolism result in lipid depot in skeletal muscle.3) During aging process, lipid metabolism disturb IGF-1/Akt/mTOR signaling pathway.4) Three weeks intervene of treadmill running can reduce lipid depot in skeletal muscle of old and young group.5) Three weeks intervene of treadmill running can induce mitochondria biogenesis.6) Three weeks intervene of treadmill running can depress lipid metabolism to increase skeletal muscle protein anabolism.