Urocortin in the ventromedial hypothalamic nucleus acts as an inhibitor offeeding behavior in rats

Urocortin (UCN), a member of the corticotropin-releasing factor (CRF) famil y, inhibits food intake when it is injected intracerebroventricularly in ra ts. To explore the site of action of UCN in feeding behavior, we examined t he effects of injection of UCN into various hypothalamic nuclei on food and water intake in 24-h fasted rats. Injection of UCN into the ventromedial h ypothalamic nucleus (VMH) significantly inhibited food and water intake ove r 3 h without sedative effect, but no significant effect was observed follo wing injection either into the lateral hypothalamic area, or the paraventri cular nucleus of the hypothalamus. To further explore the physiological sig nificance of endogenous UCN of the VMH in feeding behavior, the effect of i mmunoneutralization of hypothalamic UCN on food intake was examined. Inject ion of anti-rat UCN rabbit gamma-globulin into the bilateral VMH in freely fed rats significantly potentiated food and water intake compared with rats that received normal rabbit gamma-globulin. These results suggest that end ogenous UCN in the VMH exert inhibitory control on ingestive behavior. (C) 2000 Elsevier Science B.V. All rights reserved.