Pii: S0196-9781(00)00303-x

The present study evaluated the effects of both intraperitoneal (i.p.) and intracerebroventricular administration of selective Y1 [(Leu , Pro)-NPY] and Y2 [(Pro , Tyr)-NPY (13–36)] receptor agonists on food intake in satiated goldfish. Food intake (FI) was significantly increased by central administration of the Y1 agonist (1 mg), but not by the Y2 agonist, at 2 h postinjection. The feeding increase induced by (Leu, Pro)-NPY was in a similar magnitude to that obtained after ICV injection of the neuropeptide Y, and both feeding stimulations were reversed by the NPY (27–36), a general NPY antagonist. The i.p. administration of the agonists either did not significantly modify (Y2 agonist) or decreased (Y1 agonist) food intake in goldfish. These data indicate that it is the Y1-like (similar to Y1 and/or Y5) receptor, and not Y2, that is involved in the central modulation of the feeding behavior in goldfish. We also investigated the possible involvement of opioid peptides as mediators of the NPY stimulatory action on food intake in goldfish. The ICV administration of naloxone (10 mg), a general opioid antagonist, blocked the NPY-induced feeding in goldfish, suggesting that the opioidergic system is involved in feeding regulation by NPY. © 2000 Published by Elsevier Science Inc.