Journal of Comparative Physiology B

, Volume 171, Issue 4, pp 327–334 | Cite as

Correlations of plasma lipid metabolites with hibernation and lactation in wild black bears Ursus americanus

  • P.J. LeBlanc
  • M. Obbard
  • B.J. Battersby
  • A.K. Felskie
  • L. Brown
  • P.A. Wright
  • J.S. Ballantyne
Original Paper

Abstract.

During the denning period, black bears (Ursus americanus) are capable of enduring several months without food. At the same time, female bears that are pregnant or lactating have an added metabolic stress. Based on laboratory studies, much of the energy required to support metabolism and lactation during denning in black bears comes from lipid reserves. These lipid reserves are mobilized and the most metabolically active lipid fraction in the blood are nonesterified fatty acids (NEFA). Therefore, we hypothesized that plasma NEFAs would be higher in denning relative to active bears and in lactating relative to non-lactating female bears. We further hypothesized that in bears with elevated plasma NEFA levels, other lipid-related parameters (e.g., ketone bodies, albumin, cholesterol, lipase) would also be elevated in the plasma. Denning bears had significantly increased NEFA levels in all classes (saturates, monoenes, and polyenes). A doubling of plasma NEFA levels and a 33% increase in albumin, the plasma fatty acid binding protein, in denning bears, resulted in NEFA/albumin ratios that were higher in denning bears (4:1) compared to those of active bears (3:1). Bears became relatively ketonemic with a 17-fold increase in D-β-hydroxybutyrate levels during the denning period. Plasma cholesterol approximately doubled and lipase was ten-fold lower in denning relative to active bears. These findings indicate a strong correlation between plasma lipid metabolites and the denning period in a wild population of black bears.

Albumin Cholesterol Ketone body Nonesterified fatty acid Season 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • P.J. LeBlanc
    • 1
  • M. Obbard
    • 2
  • B.J. Battersby
    • 1
  • A.K. Felskie
    • 1
  • L. Brown
    • 2
  • P.A. Wright
    • 1
  • J.S. Ballantyne
    • 1
  1. 1.Department of Zoology, University of Guelph, Guelph, Ontario, Canada, N1G 2W1
  2. 2.Natural Heritage Science Section, Ontario Ministry of Natural Resources, PO Box 7000, 300 Water Street, Peterborough, Ontario, Canada, K9J 8M5

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