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A new perspective on adiposity in a naturally obese mammalMany mammals seasonally reduce body fat due to inherent periods of fasting, which is associated with decreased leptin concentrations. However, no data exist on the correlation between fat mass (FM) and circulating leptin in marine mammals, which have evolved large fat stores as part of their adaptation to periods of prolonged fasting. Therefore, FM was estimated (by tritiated water dilution), and serum leptin and cortisol were measured in 40 northern elephant seal (Mirounga angustirostris) pups early (<1 wk postweaning) and late (6-8 wk postweaning) during their natural, postweaning fast. Body mass (BM) and FM were reduced late; however, percent FM (early: 43.9 +/- 0.5, late: 45.5 +/- 0.5%) and leptin [early: 2.9 +/- 0.1 ng/ml human equivalents (HE), late: 3.0 +/- 0.1 ng/ml HE] did not change. Cortisol increased between early (9.2 +/- 0.5 microg/dl) and late (16.3 +/- 0.9 microg/dl) periods and was significantly and negatively correlated with BM (r = 0.426; P < 0.0001) and FM (r = 0.328; P = 0.003). FM and percent FM were not correlated (P > 0.10) with leptin at either period. The present study suggests that these naturally obese mammals appear to possess a novel cascade for regulating body fat that includes cortisol. The lack of a correlation between leptin and FM may reflect the different functions of fat between terrestrial and marine mammals.
Document ID
20040088667
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ortiz, R. M.
(University of California Santa Cruz, Santa Cruz, California 95064, United States)
Noren, D. P.
Litz, B.
Ortiz, C. L.
Date Acquired
August 21, 2013
Publication Date
December 1, 2001
Publication Information
Publication: American journal of physiology. Endocrinology and metabolism
Volume: 281
Issue: 6
ISSN: 0193-1849
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: GM-58903-01
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Regulatory Physiology

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