Feeding responses to several neuropeptide Y receptor agonists in the neonatal chick

Neuropeptide Y is one of the most potent neuropeptides known to induce feed ing in animals, and has been suggested to be a physiological signal for foo d intake. It has been also reported that intracerebroventricular injection of neuropeptide Y stimulates feeding behavior of the neonatal chick. There are many neuropeptide Y receptor agonists that have not been investigated i n feeding response of the neonatal chick, The aim of this study is to eluci date whether central injection of several neuropeptide Y receptor agonists stimulates feeding of the neonatal chick over 2 h. We found that central in jections of [Leu(31), Pro(34)]neuropeptide Y, peptide YY, human pancreatic polypeptide and rat pancreatic polypeptide significantly stimulated food in take of neonatal chicks throughout the 2-h post-injection period. Neuropept ide Y-(13-36) significantly stimulated feeding at 30 min, but not thereafte r. [D-Trp(32)]neuropeptide Y stimulated feeding at 60 and 120 min, but not 30 min, post-injection. Central administration of rat pancreatic polypeptid e, which does not increase food intake in rats, stimulated feeding in chick s. This result reflects structural differences of the neuropeptide Y recept or subtypes and/or differences in mechanisms stimulating feeding behavior b etween mammals and chickens. In conclusion, neuropeptide Y receptor agonist s, except for neuropeptide Y-(13-36), are potent stimulators of food intake in the neonatal chick. (C) 2001 Elsevier Science B.V. All rights reserved.