title: Effect of nociceptin/orphanin FQ on feeding behavior and hypothalamic neuropeptide expression in layer-type chicks.
abstract: Nociceptin/orphanin FQ (N/OFQ) was identified in 1995 as the endogenous ligand for the orphan G(i)/G(o)-coupled opioid receptor-like 1 receptor (NOP(1)). Exogenous N/OFQ increases food intake in mammals, but its effect and mode of action in chicks are not fully known. We report herein that N/OFQ (5.0 nmol) has a stimulatory effect on food intake in layer-type chicks over a 2-h period after intracerebroventricular (icv) injection. Thirty minutes after central injection of N/OFQ (5.0 nmol) the concentration of agouti-related protein (AGRP) mRNA in the diencephalon increased, while cocaine- and amphetamine-regulated transcript (CART) mRNA decreased. However, concentrations of neuropeptide Y, proopiomelanocortin and glutamate decarboxylase mRNAs, and of catecholamines and excitatory amino acids were not affected. Simultaneous administration of alpha-melanocyte stimulating hormone (alpha-MSH: 1.0 pmol), a competitor of AGRP, completely blocked the orexigenic effect of N/OFQ (5.0 nmol). These data suggest that N/OFQ functions in layer chicks as an orexigenic peptide in the central nervous system, and that the AGRP and the CART neurons may mediate this function, as in mammals.
authors.affiliation: Laboratory of Animal Behavior and Physiology, Department of Bioresource Science, Graduate School of Biosphere Science, Hiroshima University, Higashi-Hiroshima 739-8528, Japan. bungo@hiroshima-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Bungo
authors.forename: Jun-ichi
authors.initials: J
authors.lastname: Shiraishi
authors.forename: Kouichi
authors.initials: K
authors.lastname: Yanagita
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ohta
authors.forename: Masanori
authors.initials: M
authors.lastname: Fujita