Changing lanes: seasonal differences in cellular metabolism of adipocytes in grizzly bears (Ursus arctos horribilis)

AbstractObesity is among the most prevalent of health conditions in humans leading to a multitude of metabolic pathologies such as type 2 diabetes and hyperglycemia. However, there are many wild animals that have large seasonal cycles of fat accumulation and loss that do not result in the health consequences observed in obese humans. One example is the grizzly bear (Ursus arctos horribilis) that can have body fat content  >  40% that is then used as the energy source for hibernation. Previous in vitro studies found that hibernation season adipocytes exhibit insulin resistance and increased lipolysis. Yet, other aspects of cellular metabolism were not addressed, leaving this in vitro model incomplete. Thus, the curren t studies were performed to determine if the cellular energetic phenotype—measured via metabolic flux—of hibernating bears was retained in cultured adipocytes and to what extent that was due to serum or intrinsic cellular factors. Extracellular acidification rate and oxygen consumption rate were used to calculate proton efflux rate and total ATP defined as both ATP from glycolysis and from mitochondrial respiration. Hibernation adipocytes treated with hibernation serum produced less ATP and exhibited lower maximal respiration and glycolysis rates than active season adipocytes. These effec ts were reversed with serum from the opposite season. Insulin had little influence on total ATP production and lipolysis in both hibernation and active serum-treated...
Source: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology - Category: Physiology Source Type: research