Thesis
Changing lanes: seasonal differences in energy metabolism of adipocytes in grizzly bears (Ursus arctos horribilis)
Washington State University
Master of Science (MS), Washington State University
05/2021
DOI:
https://doi.org/10.7273/000000056
Handle:
https://hdl.handle.net/2376/111059
Abstract
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.
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Details
- Title
- Changing lanes
- Creators
- Hannah Hapner
- Contributors
- HEIKO JANSEN (Degree Supervisor) - Washington State University, Integrative Physiology and Neuroscience, Department ofCHARLES T ROBBINS (Committee Member) - Washington State University, Environment, School of the (CAHNRS)W. Wesley Dowd (Committee Member) - Washington State University, Biological Sciences, School ofJOANNA KELLEY (Committee Member) - Washington State University, Biological Sciences, School of
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Sciences, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Format
- pdf
- Number of pages
- 44
- Identifiers
- 99900587063801842
- Language
- English
- Resource Type
- Thesis