Involvement of orexin-A neurons but not melanin-concentrating hormone neurons in the short-term regulation of food intake in rats
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In order to elucidate the involvement of melanin-concentrating hormone (MCH) and orexin-A (ORX-A) neurons of the perifornical/lateral hypothalamic areas (PF/LH) in the regulation of food intake induced by acutely reduced glucose availability, we examined the food intake response and c-Fos expression in the MCH and ORX-A neurons in the PF/LH during 2-deoxy-d-glucose (2DG)-induced glucoprivation (400 mg/kg; i.v.) and systemic insulin-induced hypoglycemia (5 U/kg; s.c.) in male Wistar rats. The administration of both 2DG and insulin stimulated food intake and induced c-Fos expression in the ORX-A neurons corresponding to food intake, but not in the MCH neurons. These data indicate that ORX-A neurons, but not MCH neurons, play a role in the short-term regulation of food intake, and that the input signals for the neurons containing MCH and ORX-A are different, and these neurons play different roles in the regulation of feeding behavior.
KeywordsMelanin-concentrating hormone Orexin Feeding behavior Glucosensitive neurons Glucoprivation Hypoglycemia
The present study was supported by a Grant-in-Aid for Scientific Research (C) (24500975) from the Japan Society for the Promotion of Science (JSPS) and by a Nara Women’s University Intramural Grant for A. Takamata’s project.
Conflict of interest
None of the authors had a personal or financial conflict of interest.
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