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Medial hypothalamic nuclei mediate serotonin's inhibitory effect on feeding behavior
S F Leibowitz1, G F Weiss, J S Suh
1Rockefeller University, New York, NY 10021.
Pharmacology, Biochemistry, and Behavior
|December 1, 1990
Summary
Serotonin (5-HT) selectively suppresses carbohydrate intake when injected into specific hypothalamic areas, including the paraventricular nucleus (PVN). This effect was not observed in extrahypothalamic regions, indicating a localized action within the medial hypothalamus.
Area of Science:
- Neuroscience
- Neuroendocrinology
- Behavioral Neuroscience
Background:
- Serotonin (5-HT) is known to influence feeding behavior.
- Previous studies indicated 5-HT in the paraventricular nucleus (PVN) suppresses carbohydrate intake.
Purpose of the Study:
- To investigate the precise brain localization of serotonin's (5-HT) selective effect on macronutrient intake.
- To determine if this effect is limited to the PVN or extends to other hypothalamic and extrahypothalamic regions.
Main Methods:
- Injections of serotonin (5-HT) into various brain sites in freely feeding rats.
- Rats were maintained on diets consisting of pure protein, carbohydrate, or fat.
- Behavioral responses, specifically macronutrient intake, were measured after injections.
Main Results:
- Serotonin (5-HT) replicated its selective suppression of carbohydrate intake (-55%) in the PVN.
- The inhibitory effect on carbohydrate consumption was also observed in the ventromedial (VMN) and suprachiasmatic (SCN) nuclei of the hypothalamus.
- No significant effects on fat or protein intake were noted in any tested region.
- Extrahypothalamic sites, including the amygdala and nucleus accumbens, did not show a response to 5-HT.
Conclusions:
- The selective suppression of carbohydrate intake by serotonin (5-HT) is localized to the medial nuclei of the hypothalamus, not exclusive to the PVN.
- This finding highlights specific hypothalamic regions involved in macronutrient appetite regulation by serotonin.