Effects of Different Intensity Endurance Exercise on Skeletal Muscle Mass: Autophagy and Aging
QIU Shoutao;CUI Di;FU Shaoting;ZHANG Yunkun;CHEN Caizhen;LU Jian;Key Laboratory of Adolescent Health Assessment and Exercise Intervention,Ministry of Education;School of Sports and Health,East China Normal University;Nanjing Sport Institute;
Objective: To study the effects of endurance exercise on autophagy and the muscle mass during aging. Methods:Female SAMP6 mice were divided randomly into sedentary group( P,n = 5),high-( PH,n = 5),moderate-( PM,n = 5)and low-( PL,n = 5) intensity exercise group. The SAMR1 mice were assigned as the normal control( R,n = 5). The mice of PH,PMand PL undertook 8-week treadmill training,and the speed verified as 28,18 and 8 m / min separately. Results:1) Compared to R,the body weight of SAMP6 mice increased obviously( P 0. 05) while the skeletal muscle mass of P,PMand PL dropped( P 0. 05); the myofiber cross-section area in group P decreased while the gap of myofiber increased. The irregular shape of myofiber appeared and the cell nucleus mediated; the MHC1 and Myo D1 mRNA decreased sharply in group P( P 0. 05) while MSTN mRNA expression up regulated seriously( P 0. 05); compared to P,the muscle mass and the myofiber cross-section area of PH increased and the MSTN mRNA relative content in PH,PMand PL decreased incredibly. 2) Compared to R,both mRNA and protein content of p62 accelerated in P; compared to P,the ratio of LC3Ⅱ / LC3Ⅰ increased in PM,higher than it in PL,and the p62 protein content down regulated in PH,PMand PL.Conclusions: 1) It was implied that sarcopenia occurred in the SAMP6 mice with the body weight increasing and the skeletal muscle decreasing,and this phenomena can be ameliorated by endurance exercise,especially the high-intensity exercise.2) In the process of aging,it is the degradation impairment of autophagy that involves in the induction of sarcopenia,and the autophagy regulation induced by endurance exercise,especially the moderate-intensity exercise,plays an important role in the exercise therapeutic of sarcopenia.