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Estradiol decreases the orexigenic effect of melanin-concentrating hormone in ovariectomized rats
Michelina M Messina1, Gretha Boersma, J Michael Overton
1Program in Neuroscience, Florida State University, Tallahassee, FL 32306-1270, USA.
Abstract:
Estradiol exerts an inhibitory effect on food intake via interactions with anorexigenic peptides, like cholecystokinin, that function to decrease meal size. It is currently unknown whether estradiol also interacts with orexigenic compounds implicated in the physiological control of food intake. Thus, the primary goal of this study was to determine whether estradiol decreases the orexigenic effect of melanin-concentrating hormone (MCH), a neuropeptide that, like estradiol, appears to influence food intake by selectively affecting the controls of meal size. Food and water intake were monitored following lateral ventricular (icv) infusions of 5 mug MCH or saline vehicle in oil- and estradiol-treated ovariectomized rats. MCH increased food intake throughout the first 4 h of the dark phase in oil-treated rats, but only for the last 2 h of the same 4-h interval in estradiol-treated rats. As a result, the orexigenic effect of MCH was significantly lower in estradiol-treated rats, relative to oil-treated rats. During this interval of MCH-stimulated feeding, a prandial increase in water intake was not observed in either oil- or estradiol-treated rats. We conclude that estradiol decreases the orexigenic effect of MCH in ovariectomized rats.
Insights
Estradiol reduces the appetite-stimulating effect of melanin-concentrating hormone (MCH) in rats. This finding suggests estradiol influences feeding behavior by modulating orexigenic neuropeptides, impacting meal size control.
Area of Science:
- Neuroendocrinology
- Appetite Regulation
- Hormonal Influences on Feeding Behavior
Background:
- Estradiol (hormone) inhibits food intake by interacting with anorexigenic peptides.
- The interaction between estradiol and orexigenic (appetite-stimulating) compounds is not well understood.
- Melanin-concentrating hormone (MCH) is an orexigenic neuropeptide that influences meal size.
Purpose of the Study:
- To investigate whether estradiol attenuates the orexigenic effect of MCH.
- To determine if estradiol modulates the impact of MCH on food intake control.
Main Methods:
- Ovariectomized rats received intracerebroventricular (icv) infusions of MCH or saline.
- Rats were treated with either oil vehicle or estradiol.
- Food and water intake were monitored over a 4-hour period during the dark phase.
Main Results:
- MCH increased food intake in oil-treated rats for 4 hours.
- In estradiol-treated rats, MCH-induced feeding was observed only during the last 2 hours of the 4-hour period.
- The orexigenic effect of MCH was significantly diminished in estradiol-treated rats compared to oil-treated controls.
Conclusions:
- Estradiol significantly decreases the orexigenic effect of MCH in ovariectomized rats.
- Estradiol may influence feeding behavior by modulating the action of orexigenic neuropeptides like MCH.
- This suggests a role for estradiol in the fine-tuning of meal size regulation through orexigenic pathways.
