title: Inhibitory effect of chicken gonadotropin-releasing hormone II on food intake in the goldfish, Carassius auratus.
abstract: Gonadotropin-releasing hormone (GnRH) is an evolutionarily conserved neuropeptide with 10 amino acid residues, which possesses some structural variants. A molecular form known as chicken GnRH II ([His(5) Trp(7) Tyr(8)] GnRH, cGnRH II) is widely distributed in vertebrates, and has recently been implicated in the regulation of sexual behavior and food intake in an insectivore, the musk shrew. However, the influence of cGnRH II on feeding behavior has not yet been studied in model animals such as rodents and teleost fish. In this study, therefore, we investigated the role of cGnRH II in the regulation of feeding behavior in the goldfish, and examined its involvement in food intake after intracerebroventricular (ICV) administration. ICV-injected cGnRH II at graded doses, from 0.1 to 10 pmol/g body weight (BW), induced a decrease of food consumption in a dose-dependent manner during 60 min after treatment. Cumulative food intake was significantly decreased by ICV injection of cGnRH II at doses of 1 and 10 pmol/g BW during the 60-min post-treatment observation period. ICV injection of salmon GnRH ([Trp(7) Leu(8)] GnRH, sGnRH) at doses of 0.1-10 pmol/g BW did not affect food intake. The anorexigenic action of cGnRH II was completely blocked by treatment with the GnRH type I receptor antagonist, Antide. However, the anorexigenic action of cGnRH II was not inhibited by treatment with the corticotropin-releasing hormone (CRH) 1/2 receptor antagonist, *-helical CRH((9-41)), and the melanocortin 4 receptor antagonist, HS024. These results suggest that, in the goldfish, cGnRH II, but not sGnRH, acts as an anorexigenic factor, as is the case in the musk shrew, and that the anorexigenic action of cGnRH II is independent of CRH- and melanocortin-signaling pathways.
authors.affiliation: Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan. kmatsuda@sci.u-toyama.ac.jp
authors.forename: Kouhei
authors.initials: K
authors.lastname: Matsuda
authors.forename: Kouta
authors.initials: K
authors.lastname: Nakamura
authors.forename: Sei-Ichi
authors.initials: S
authors.lastname: Shimakura
authors.forename: Tohru
authors.initials: T
authors.lastname: Miura
authors.forename: Haruaki
authors.initials: H
authors.lastname: Kageyama
authors.forename: Minoru
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Seiji
authors.initials: S
authors.lastname: Shioda
authors.forename: Hironori
authors.initials: H
authors.lastname: Ando
mesh_terms: D000818:Animals; D000855:Anorexia / Q000139:chemically induced; D002645:Chickens; D003346:Corticotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006054:Goldfish / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D018043:Receptors, Corticotropin / Q000037:antagonists & inhibitors; D012727:Sex Characteristics
chemical_list: C116098:HS 024; D006727:Hormone Antagonists; D009842:Oligopeptides; D010446:Peptide Fragments; D010456:Peptides, Cyclic; D018043:Receptors, Corticotropin; D007987:Gonadotropin-Releasing Hormone; D003346:Corticotropin-Releasing Hormone; C047717:LHRH, His(5)-Trp(7)-Tyr(8)-; C057022:iturelix; C045089:corticotropin releasing hormone (9-41)