Impaired leptin responsiveness in aged rats
Impaired leptin responsiveness in aged rats. P J Scarpace , M Matheny , R L Moore and N Tümer Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, University of Florida College of Medicine, Gainesville 32608-1197, USA. Abstract We previously reported that...
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Published in | Diabetes (New York, N.Y.) Vol. 49; no. 3; pp. 431 - 435 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
United States
American Diabetes Association
01.03.2000
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Subjects | |
Online Access | Get full text |
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Summary: | Impaired leptin responsiveness in aged rats.
P J Scarpace ,
M Matheny ,
R L Moore and
N Tümer
Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, University of Florida College
of Medicine, Gainesville 32608-1197, USA.
Abstract
We previously reported that adiposity and serum leptin levels increase with age in male F-344xBN rats and that when physiological
levels of serum leptin are manipulated by fasting, there is a corresponding reciprocal change in hypothalamic neuropeptide
Y (NPY) mRNA in young rats, but there are no changes in older rats. These findings suggest that the regulation of hypothalamic
NPY mRNA by leptin may be impaired with age. To test this hypothesis, we infused saline or leptin for 7 days into ad libitum-fed
rats and compared these with saline-infused rats that were pair-fed the amount of food consumed by the leptin-treated rats.
We examined daily food consumption, body weight, whole-body oxygen consumption, serum leptin, and NPY mRNA in the hypothalamus.
Food consumption decreased by 50% in the leptin-infused compared with the saline-infused young rats but only decreased by
20% in the aged rats. In the leptin-treated young rats, there was a 24% increase in oxygen consumption compared with the pair-fed
rats, but there were no changes in oxygen consumption in the aged rats. Leptin infusion diminished hypothalamic NPY levels
by nearly 50% compared with pair-fed young rats, whereas there were no changes in the hypothalamic NPY mRNA levels in senescent
rats. In summary, aged rats demonstrate a reduced responsiveness to leptin, including a diminished decrease in food intake
and no increase in energy expenditure. These diminished responses to leptin were associated with and may be the result of
an impaired suppression of hypothalamic NPY mRNA levels. This leptin resistance may be due to either the elevated obesity
and serum leptin with age or due to age itself, or both. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0012-1797 1939-327X |
DOI: | 10.2337/diabetes.49.3.431 |