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

• Main Author: Hapner, Hannah
• Format: Text
• Language: English
• Published: Washington State University 2022
• Subjects: Lanes; Ursus arctos
• Online Access: https://dx.doi.org/10.7273/000000056; https://rex.libraries.wsu.edu/esploro/outputs/graduate/99900587063801842

Obesity 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 exhibit the health : consequences observed in obese humans. One example is the grizzly bear (Ursus arctos : horribilis) that can have body fat contents >40%. It is known that hibernating bears survive by : metabolizing their fat stores. Previous in vitro studies found that hibernation season adipocytes : are insulin resistant and exhibit increased lipolysis as measured by extracellular glycerol. Yet, : other aspects of cellular metabolism were not addressed, leaving this in vitro model incomplete. : To this end, the current 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 : (ECAR) and oxygen consumption rate (OCR) were used to calculate proton efflux rate (PER), : and total ATP defined as both ATP from glycolysis and from mitochondrial respiration. : Hibernation serum treated adipocytes lack metabolic flexibility and produce less ATP than active : serum treated adipocytes. Insulin had minor influence on ATP production, but inhibited lipolysis in active but not hibernation serum treated adipocytes. This suggests that the reduction in : glycolysis during hibernation is occurring downstream of insulin signaling and glucose uptake. : These findings reveal a potent seasonal serum effect on metabolic capacity of bear adipocytes. : Elucidation of responsible serum components involved and the cellular mechanisms that enable : these influences may provide a novel avenue for the development of future treatments of human : metabolic diseases.