Abstract
BackgroundGlucocorticoids (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.ResultsAn interaction between DEX injection and dietary energy level was found on hypothalamic corticotropin-releasing 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 mRNA 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 mRNA levels (P < 0.05). Under re-feeding conditions, DEX treatment significantly decreased hypothalamic expression levels of NPY and agouti-related peptide (AgRP) but significantly increased the level of hypothalamic CRH expression (P < 0.05).ConclusionA regulatory network formed by NPY, AgRP 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.Electronic supplementary materialThe online version of this article (doi:10.1186/s40104-016-0084-x) contains supplementary material, which is available to authorized users.
Highlights
Glucocorticoids (GCs) are involved in the control of appetite in birds and mammals
DEX treatment significantly increased the plasma glucose concentration (P < 0.05), but diet treatment had no significant effect (P > 0.05, Fig. 2c). Both diet and DEX treatments had an effect on the plasma glucose concentration in re-fed chickens, and feeding with low-fat diet (LFD) and DEX treatments significantly increased the plasma glucose concentration (P < 0.05, Fig. 2d)
The results suggest that a regulatory network formed by neuropeptide Y (NPY), agouti-related peptide (AgRP) and corticotropinreleasing hormone (CRH) is associated with the appetite-control of GCs
Summary
The effect of GCs on feed intake in birds depends on their dietary energy level. There are a population of neurons influencing appetite in hypothalamus, such as orexigenic neuropeptides (e.g., neuropeptide Y [NPY], agouti-related peptide [AgRP]) [1], and anorexigenic neuropeptides (e.g., proopiomelanocortin [POMC], and corticotropin-releasing hormone, [CRH]) [2, 3]. The release of these neuropeptides is closely associated with the feeding state and dietary energy level. The effect of GCs on feed intake in birds depends on its dosage. Bartov [13] showed that the effect of GCs on appetite was diet-type dependent, and GCs could
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