Intracerebroventricular injection of agouti-related protein attenuates the anorexigenic effect of alpha-melanocyte stimulating hormone in neonatal chicks

It is well known that α-melanocyte stimulating hormone (α-MSH) inhibits feeding via melanocortin receptor-4 (MC4R) in the mammalian brain. The anorexigenic effect of α-MSH is attenuated by agouti-related protein (AGRP), an antagonist for MC4R. Present studies were carried out to clarify whether human AGRP (86–132) antagonizes the anorexigenic effect of α-MSH in broiler chicks. Intracerebroventricular injection of AGRP attenuated the anorexigenic effect of α-MSH. Furthermore, AGRP stimulated food intake of layer-type chicks under an ad libitum feeding condition but not broiler chicks, suggesting that the orexigenic effect of AGRP is different between two breeds. These also imply that the extent of the anorexigenic effect of endogenous α-MSH is different among two breeds. This may be a part of the difference in food intake between two breeds.