Aging and hypobaric hypoxia induced skeletal muscle protein loss: A comparative experimental study using rat model

Skeletal muscle protein concentrations are regulated by protein synthesis and protein degradation mechanisms. In the present study, we compared two muscle loss phenomenon i.e., hypobaric hypoxia and sarcopenia. Male SD rats were distributed into three groups: control, aged and hypobaric hypoxia (HH) exposed rats. Results showed elevated levels of oxidative stress marker, ROS and GSSG: GSH in both stresses which corroborated with decreased in thiol content. Ergo, protein and lipid oxidation also increased in aged rats as contrast to HH exposed and control rats. Moreover, protein degradative machinery and apoptosis related markers, 20S proteasome, caspase-3 and caspase-9 was also upregulated in the aged and HH-exposed rats. Interestingly, the activity of two important proteins i.e., p-Akt and heat shock protein-60 (HSP60) were found different in these two stresses. p-Akt and HSP60 protein were elevated in HH-exposed rats whilst decreased activity was noted in case of aged rats. These results suggest that age is natural phenomenon that resulted into muscle protein loss, whereas HH-exposure has entirely different degradation mechanism. In the event of HH-exposure, cell has mechanisms to cope up with the unfavorable stress condition but degradation mechanisms are highly activated which led to muscle protein loss.