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Starvation: early signals, sensors, and sequelae
M F Dallman1, S F Akana, S Bhatnagar
1Department of Physiology, University of California, San Francisco 94143-0444, USA. dallman@itsa.ucsf.edu
Endocrinology
|August 28, 1999
Summary
Starvation triggers rapid hormonal and metabolic signals to the hypothalamus within 4 hours. Leptin secretion decreases before synthesis changes, indicating independent regulation.
Area of Science:
- Neuroendocrinology
- Metabolic Regulation
- Physiology
Background:
- Understanding the body's response to starvation is crucial for metabolic and neuroendocrine research.
- Identifying the sequence of signaling events during fasting provides insights into energy homeostasis.
Purpose of the Study:
- To elucidate the temporal sequence of signals, their reception, and the body's responses to starvation.
- To investigate the interplay between hormones, metabolites, and neuropeptide expression during fasting.
Main Methods:
- Rats were sampled at 2- to 6-hour intervals after food removal.
- Measurements included metabolites, hormones (insulin, corticosterone), hypothalamic neuropeptide Y mRNA, fat depots, and leptin expression.
Main Results:
- Within 4 hours, insulin decreased, while free fatty acids (FFA) and corticosterone increased; leptin and glucose levels dropped.
- Neuropeptide Y mRNA levels rose 6 hours post-food removal.
- Leptin secretion decreased before changes in leptin mRNA or fat depot weight.
Conclusions:
- Hormonal and metabolic signals rapidly inform the hypothalamus about starvation within 4 hours.
- Hypothalamic neuropeptide synthesis responds quickly to altered metabolic cues.
- Leptin secretion is regulated independently of synthesis and fat depot changes during early starvation.