Meeting Abstract
Bears are able to limit muscle atrophy during hibernation, a period of low metabolic rates, decreased physical activity, anorexia, and adipsia. Even though skeletal muscle function and architecture is regulated through multiple physiological pathways, the role of satellite cells (SCs), and their endocrine signaling, in hibernating species remain understudied. We aimed to elucidate in vitro SC proliferation and differentiation associated with physical movement and serum myostatin in the American black bear (ABB) (Ursus americanus) during fall hyperphagia, hibernation, and spring activity. We performed muscle biopsies and collected sera from adult males and females (n= 2 and 4, respectively) at Virginia Tech’s Black Bear Research Center. Our results show that: 1) SCs maintain their ability to proliferate in vitro at similar rates throughout all ABB metabolic states, including hibernation, 2) in vitro SC differentiation and myogenic ability is increased during ABB hibernation, coinciding with a decrease in circulating serum myostatin, and 3) there are dramatically different nuclei fusion rates (i.e., differentiation) between males and females with cubs post hibernation, suggesting that reproductive females face additional metabolic constraints during spring arousal in order to maintain the integrity of skeletal muscle. We propose that maintaining the SC proliferative and differentiation abilities during hibernation is an important potential pathway for limiting muscle atrophy during bear hibernation. Functional aspects of bear muscle conservation are interesting for understanding bear physiological adaptations to hibernation and also potentially for elucidating avenues to improve treatments for human muscular disorders.
