Physical activity improves sarcopenia in a murine model by enhancing the proliferative potential of muscle stem cells, oxidative capacity of mitochondrial enzymes and expression of Sestrins

Abstract

Sarcopenia is a major health issue in old age. Underlying molecular mechanisms in its genesis remain unclear and optimal animal models are yet to be established. A novel animal model was developed to identify structural and functional changes in skeletal muscles from sarcopenia. The influence of physical activity on animals of the sarcopenic model with respect to the expression of anti-oxidant proteins, mitochondrial oxidative capacity, and effect on muscle stem cells (MuSCs), were assessed. Male C57Bl/6 mice of different age groups were recruited: Y-Cntrl (young-control), A-Cntrl (aged-control), SAR-model and SAR-INT. SAR-model group was kept in a retrofitted confined cage and was fed with customized protein-restricted diet (14% protein), which is considered as a sarcopenic featured model. SAR-INT served as the intervention group. Three parameters, namely, muscle mass, grip strength, and physical endurance, were used to confirm the sarcopenic state. All physical parameters deteriorated most in SAR-model and it improved in the SAR-INT group. The impact of physical activity on the SAR-INT group was also evidenced by the improved proliferative potential of MuSCs determined by flow cytometric analysis. Compared with the SAR-model, the SAR-INT exhibited significant improvement in the oxidative capacity of mitochondrial enzymes and increased expression of anti-oxidant proteins, sestrins. In conclusion, physical activity improved physical parameters, MuSC proliferative potential, mitochondrial enzyme oxidative capacity and sestrin expression in sarcopenic animals. Hence, SAR-model in mice can serve as a novel sarcopenic model, physical activity provides scope for improvement in sarcopenic population and sestrin molecule can have a potential implication on sarcopenia.