Hypothalamic Akt-mediated signaling regulates food intake in chicks

The central anorexigenic mechanism seems to be similar in mammals and chicks, because the appetite-suppressive action of a number of peptide hormones is similar in both species. Accumulating evidence in mammals has revealed that hypothalamic Akt-mediated signaling factors (for instance, mTOR and FOXO1) are significantly involved in the regulation of food intake. However, the role of hypothalamic Akt in feeding regulation is yet to be determined in chickens. In this study, we showed that pAkt (Thr308)/Akt, pFOXO1/FOXO1, and pS6 levels were significantly increased in the hypothalami of chicks refed 1 h after a 24 h-fast in correlation to increases in the plasma concentrations of insulin, one of the activators of the Akt-mediated signaling pathways. In addition, central administration of insulin increased the phosphorylation of Akt, FOXO1, and S6 in chicken hypothalami. Furthermore, intracerebroventricular injections of both phosphoinositide 3-kinase inhibitor LY294002 and mTOR inhibitor rapamyacin enhanced the food intake of chicks. These findings suggest that hypothalamic Akt-mediated signaling pathways contribute to the regulation of food intake in chicks.