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Published on: September 7, 2013
Melanin-concentrating hormone acutely stimulates feeding, but chronic administration has no effect on body weight
1Division of Endocrinology and Metabolic Medicine, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
Abstract:
Melanin-concentrating hormone (MCH) has recently been proposed as both a central stimulator and an inhibitor of food intake. To clarify its role, we investigated the effects of MCH and the prepro-MCH-derived peptide neuropeptide E-I injected intracerebroventricularly (icv) in rats. MCH (0.15-15 micrograms) was injected icv at the beginning of the light phase. Food intake at 2 h showed a dose-dependent increase from 325 +/- 7% of the control value (1.5-microgram dose; P < 0.05) to 462 +/- 30% of the control value (15-microgram dose; P < 0.005). When 10 ng, 100 ng, and 5 micrograms MCH were injected icv at the beginning of the dark phase, only 5 micrograms stimulated feeding (166 +/- 16% of the control value; P < 0.05). At no dose did MCH inhibit feeding. Twice daily icv injections of MCH (5 micrograms) caused an average 197 +/- 9% increase in 2-h food intake for the first 5 days. Injections from days 6-8 did not stimulate feeding. Food intake and body weight at 24 h remained unchanged. Intracerebroventricular neuropeptide E-I had no effect on food intake alone and did not alter MCH-induced feeding. These studies show a dose-dependent stimulation of feeding by acute central administration of MCH. Tolerance is seen with chronic administration. These findings support a role for MCH in the immediate regulation of food intake, but not in body weight control.
Insights
Melanin-concentrating hormone (MCH) stimulates food intake in rats when administered centrally. However, this effect diminishes with repeated MCH administration, indicating tolerance and suggesting MCH
Area of Science:
- Neuroscience
- Endocrinology
- Physiology
Background:
- Melanin-concentrating hormone (MCH) has a debated role in regulating appetite.
- Previous studies suggested MCH could both stimulate and inhibit food intake.
Purpose of the Study:
- To clarify the role of MCH in food intake regulation.
- To investigate the effects of MCH and neuropeptide E-I on feeding behavior in rats.
Main Methods:
- Rats received intracerebroventricular (icv) injections of MCH or neuropeptide E-I.
- Food intake was measured at 2-hour intervals after acute and chronic administration.
- Dose-response effects were examined during light and dark phases.
Main Results:
- Acute central MCH administration dose-dependently increased food intake.
- MCH stimulated feeding during the light phase more potently than the dark phase.
- Chronic MCH administration led to tolerance, with feeding stimulation diminishing over time.
- Neuropeptide E-I did not affect food intake or MCH-induced feeding.
Conclusions:
- Central MCH acutely stimulates feeding in a dose-dependent manner.
- Tolerance develops with repeated MCH administration.
- MCH plays a role in the immediate regulation of food intake, not long-term body weight control.
