| Abstract: | Background: Glucocorticoids(GCs) are involved in the control of appetite in birds and mammals. The effect of GCs on feed intake in birds depends on their dietary energy level. But the regulation mechanism of GCs on appetite is still unclear in chickens facing to different energy level. An experiment was conducted to investigate the effect of dexamethasone(DEX) on hypothalamic expression of appetite-related peptides in chickens fed high/low fat diet and under fasting/feeding condition.Results: An interaction between DEX injection and dietary energy level was found on hypothalamic corticotropinreleasing hormone(CRH) gene expression in fasted chickens(P 0.05). The chickens, given a DEX injection and a low fat diet treatment, had the highest CRH m RNA levels than any of the fasted chickens given treatments(P 0.05).Under fasting conditions, the DEX treatment significantly increased hypothalamic neuropeptide Y(NPY) and GC receptors m RNA levels(P 0.05). Under re-feeding conditions, DEX treatment significantly decreased hypothalamic expression levels of NPY and agouti-related peptide(Ag RP) but significantly increased the level of hypothalamic CRH expression(P 0.05).Conclusion: A regulatory network formed by NPY, Ag RP and CRH is associated with the appetite-control by GCs.The result suggests that the regulation of GCs on orexigenic neuropeptides expression is dependent at least partially on dietary energy level and feeding state. |
