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Impaired leptin responsiveness in aged rats.
P J Scarpace1, M Matheny, R L Moore
1Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, University of Florida College of Medicine, Gainesville 32608-1197, USA.
Diabetes
|June 27, 2000
Summary
Aging impairs leptin
Area of Science:
- Gerontology
- Neuroendocrinology
- Obesity Research
Background:
- Adiposity and serum leptin increase with age in male rats.
- Leptin's regulation of hypothalamic neuropeptide Y (NPY) mRNA is age-dependent.
Purpose of the Study:
- To investigate age-related impairment in leptin's regulation of hypothalamic NPY mRNA.
- To test the hypothesis that leptin's effectiveness diminishes with age.
Main Methods:
- Infused leptin or saline into young and aged rats for 7 days.
- Monitored food consumption, body weight, oxygen consumption, serum leptin, and hypothalamic NPY mRNA.
- Utilized pair-feeding to control for food intake variations.
Main Results:
- Aged rats showed a blunted decrease in food intake (20%) compared to young rats (50%) following leptin infusion.
- Leptin infusion did not increase oxygen consumption in aged rats, unlike young rats (24% increase).
- Hypothalamic NPY mRNA suppression by leptin was impaired in aged rats compared to young rats.
Conclusions:
- Aged rats exhibit reduced responsiveness to leptin, a phenomenon termed leptin resistance.
- This resistance is linked to impaired suppression of hypothalamic NPY mRNA.
- Leptin resistance in aging may stem from increased adiposity, elevated serum leptin, or age itself.