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Differential Change...
Differential Changes in Circulating Steroid Hormones in Hibernating Brown Bears : Preliminary Conclusions and Caveats
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- Frøbert, Anne Mette (författare)
- Department of Chemistry and Bioscience, Faculty of Engineering and Science, Aalborg University, Aalborg, Denmark
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- Toews, Julia N. C. (författare)
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver British Columbia, Canada
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- Nielsen, Claus G. (författare)
- Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
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- Brohus, Malene (författare)
- Department of Chemistry and Bioscience, Faculty of Engineering and Science, Aalborg University, Aalborg, Denmark
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- Kindberg, Jonas (författare)
- Swedish University of Agricultural Sciences,Sveriges lantbruksuniversitet,Institutionen för vilt, fisk och miljö,Department of Wildlife, Fish and Environmental Studies,Norwegian Institute for Nature Research (NINA)
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- Jessen, Niels (författare)
- Research Laboratory for Biochemical Pathology, Department of Clinical Medicine, Aarhus University, Aarhus, Denmark; Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark
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- Fröbert, Ole, 1964- (författare)
- Region Örebro län,Örebro universitet, Institutionen för medicinska vetenskaper,Steno Diabetes Center Aarhus, Aarhus University Hospital, Aarhus, Denmark; Department of Cardiology, Faculty of Health, Örebro University, Örebro, Sweden; Department of Clinical Medicine, Aarhus University Health, Aarhus, Denmark; Department of Clinical Pharmacology, Aarhus University Hospital, Denmark
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- Hammond, Geoffrey L. (författare)
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver British Columbia, Canada
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- Overgaard, Michael T. (författare)
- Department of Chemistry and Bioscience, Faculty of Engineering and Science, Aalborg University, Aalborg, Denmark
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(creator_code:org_t)
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- University of Chicago Press, 2022
- 2022
- Engelska.
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Ingår i: Physiological and Biochemical Zoology. - : University of Chicago Press. - 1522-2152 .- 1537-5293. ; 95:5, s. 365-378
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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https://res.slu.se/i...
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Abstract
Ämnesord
Stäng
- Brown bears are obese when they enter the den, and after 6 mo of hibernation and physical inactivity, bears show none of the adverse consequences of a sedentary lifestyle in humans, such as cardiovascular disease, type 2 diabetes, and kidney failure. The metabolic mechanisms that drive hibernation physiology in bears are poorly defined, but systemic endocrine regulators are likely involved. To investigate the potential role of steroid hormones, we quantified the total levels of 12 steroid hormones, the precursor cholesterol, sex hormone-binding globulin (SHBG), and corticosterone-binding globulin (CBG) in paired serum samples from subadult free-ranging Scandinavian brown bears during the active and hibernation states. During hibernation, androstenedione and testosterone were significantly decreased in subadult female bears (n=13), whereas they increased in all males but one (n=6) and therefore did not reach a significant difference. Despite this difference, SHBG increased more than 20-fold during hibernation for all bears. Compared with SHBG concentrations in humans, bear levels were very low in the active state, but during hibernation, levels equaled high levels in humans. The increased SHBG levels likely maintain a state of relative quiescence of the reproductive hormones in hibernating bears. Interestingly, the combination of SHBG and testosterone levels results in similar free bioavailable testosterone levels of 70-80 pM in both subadult and adult sexually active male bears, suggesting a role for SHBG in controlling androgen action during hibernation in males. Dehydroepiandrosterone sulfate, dihydrotestosterone, and estradiol levels were below the detection limit in all but one animal. The metabolically active glucocorticoids were significantly higher in both sexes during hibernation, whereas the inactive metabolite cortisone was reduced and CBG was low approaching the detection limit. A potential caveat is that the glucocorticoid levels might be affected by the ketamine applied in the anesthetic mixture for hibernating bears. However, increased hibernating cortisol levels have consistently been reported in both black bears and brown bears. Thus, we suggest that high glucocorticoid activity may support the hibernation state, likely serving to promote lipolysis and gluconeogenesis while limiting tissue glucose uptake to maintain a continuous glucose supply to the brain.
Ämnesord
- NATURVETENSKAP -- Biologi -- Zoologi (hsv//swe)
- NATURAL SCIENCES -- Biological Sciences -- Zoology (hsv//eng)
Nyckelord
- corticosteroid-binding globulin (CBG)
- corticosteroids
- hibernation
- progestogens
- sex hormone-binding globulin (SHBG)
- sex hormones
- steroids
- Ursus arctos
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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Frøbert, Anne Me ...
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Toews, Julia N. ...
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Nielsen, Claus G ...
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Brohus, Malene
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Kindberg, Jonas
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Jessen, Niels
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Fröbert, Ole, 19 ...
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Hammond, Geoffre ...
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Overgaard, Micha ...
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