Type-specific and hibernation-associated skeletal muscle remodeling of the back muscle in Syrian hamsters.

Skeletal muscles can undergo remodeling in response to physical, nutritional, and environmental conditions. To understand skeletal muscle remodeling associated with mammalian hibernation, we investigated the remodeling of skeletal muscles throughout hibernation in Syrian hamsters. We found that hibernating hamsters under winter-like hibernation-induction conditions exhibited lower skeletal muscle mass and thinner muscle fibers, particularly fast-twitch fibers of Type IIb and IIx, than euthermic hamsters kept under summer-like conditions. However, hamsters that were unresponsive to hibernation induction under winter-like conditions (UnHIB) were less susceptible to decreases in muscle mass and fiber size. The expression levels of Mstn and Sln, which were predominantly detected in fast-twitch or slow-twitch muscle fibers, respectively, were significantly altered in hibernating but not in UnHIB hamsters. Thus, we identified skeletal muscle remodeling associated with hibernation.