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

It is well known that a-melanocyte stimulating hormone (a-MSH) inhibits fee ding via melanocortin receptor-4 (MC4R) in the mammalian brain. The anorexi genic effect of a-MSH is attenuated by agouti-related protein (AGRP), an an tagonist for MC4R. Present studies were carried out to clarify whether huma n AG RP (86-132) antagonizes the anorexigenic effect of alpha -MSH in broil er chicks. Intracerebroventricular injection of AGRP attenuated the anorexi genic effect of alpha -MSH. Furthermore, AGRP stimulated food intake of lay er-type chicks under an ad libitum feeding condition but not broiler chicks , suggesting that the orexigenic effect of AGRP is different between two br eeds. These also imply that the extent of the anorexigenic effect of endoge nous alpha -MSH is different among two breeds. This may be a part of the di fference in food intake between two breeds. (C) 2001 Elsevier Science Irela nd Ltd. All rights reserved.