• Open Access

Brown Bears (Ursus arctos) Seem Resistant to Atherosclerosis ­Despite Highly Elevated Plasma Lipids during Hibernation and Active State

Authors

  • Karin Arinell M.D.,

    1. Department of Cardiology, Örebro University Hospital, Örebro, Sweden
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  • Berolla Sahdo M.Sc.,

    1. Department of Clinical Medicine, Örebro University, Örebro, Sweden
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  • Alina L. Evans D.V.M., M.P.H.,

    1. Faculty of Forestry and Wildlife Management, Hedmark University College, Campus Evenstad, Norway
    2. Section of Arctic Veterinary Medicine, Norwegian School of Veterinary Science, Tromsø, Norway
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  • Jon M. Arnemo D.V.M., Ph.D.,

    1. Faculty of Forestry and Wildlife Management, Hedmark University College, Campus Evenstad, Norway
    2. Department of Wildlife, Fish and Environmental Studies, Faculty of Forest Sciences, Swedish University of Agricultural Sciences, Umeå, Sweden
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  • Ulrik Baandrup M.D., Ph.D.,

    1. Department of Pathology, Vendsyssel Hospital, Hjørring, Denmark
    2. Faculty of Medical Sciences, Aalborg, Denmark
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  • Ole Fröbert M.D., Ph.D.

    1. Department of Cardiology, Örebro University Hospital, Örebro, Sweden
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  • The work presented here was carried out in collaboration between all authors. KA, BS, and OF defined the research subject. ALE and JMA designed and supervised capture and fieldwork. ALE carried out and supervised sampling of bears shot during hunting. BS carried out blood sample laboratory experiments and UB designed and carried out histologypathology. KA and OF analyzed the data, interpreted the results and wrote the paper. All authors have contributed to, seen and approved the manuscript.

Ole Fröbert (ole.frobert@orebroll.se)

Abstract

Hibernation is an extreme physiological challenge for the brown bear (Ursus arctos) in which metabolism is based mainly on lipids. The study objective was to compare plasma lipids in hibernating and active free-ranging brown bears and relate them to arterial histopathology. Blood was drawn from seven immobilized free-ranging brown bears (three females, 2–3 years old) during hibernation in February and from the same bears while active in June and analyzed by enzymatic and automated hematology methods within 48 hours of sampling. Left anterior descending coronary arteries and aortic arches from 12 bears (six females, 1.5–12 years old) killed in hunting were examined by histopathology. Total plasma cholesterol decreased from hibernation to the active period (11.08 ± 1.04 mmol/L vs. 7.89 ± 1.96 mmol/L, P= 0.0028) as did triglyceride (3.16 ± 0.62 mmol/L vs. 1.44 ± 0.27 mmol/L, P= 0.00012) and LDL cholesterol (4.30 ± 0.71 mmol/L vs. 2.02 ± 1.03 mmol/L, P= 0.0075), whereas HDL cholesterol was unchanged. No atherosclerosis, fatty streaks, foam cell infiltration, or inflammation were seen in any arterial samples. Brown bears tolerate elevated cholesterol levels, obesity, physical inactivity, and circulatory slow flow during hibernation without signs of ­atherosclerosis. This species might serve as a reverse translational model for atherosclerosis resistance. Clin Trans Sci 2012; Volume 5: 269–272

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