title: Regulation by orexin of feeding behaviour and locomotor activity in the goldfish.
abstract: Orexin is a hypothalamic neuropeptide that is implicated in the regulation of feeding behaviour and the sleep-wakefulness cycle in mammals. However, in spite of a growing body of knowledge concerning orexin in mammals, the orexin system and its function have not been well studied in lower vertebrates. In the present study, we first examined the effect of feeding status on the orexin-like immunoreactivity (orexin-LI) and the expression of orexin mRNA in the goldfish brain. The number of cells showing orexin-LI in the hypothalamus of goldfish brain showed a significant increase in fasted fish and a significant decrease in glucose-injected fish. The expression level of orexin mRNA in the brains of fasted fish increased compared to that of fed fish. We also examined the effect of an i.c.v. injection of orexin or an anti-orexin serum on food intake and locomotor activity in the goldfish. Administration of orexin by i.c.v. injection induced a significant increase of food intake and locomotor activity, whereas i.p. injection of glucose or i.c.v. injection of anti-orexin serum decreased food consumption. These results indicate that the orexin functions as an orexigenic factor in the goldfish brain.
authors.affiliation: Department of Anatomy, Showa University School of Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nakamachi
authors.forename: K
authors.initials: K
authors.lastname: Matsuda
authors.forename: K
authors.initials: K
authors.lastname: Maruyama
authors.forename: T
authors.initials: T
authors.lastname: Miura
authors.forename: M
authors.initials: M
authors.lastname: Uchiyama
authors.forename: H
authors.initials: H
authors.lastname: Funahashi
authors.forename: T
authors.initials: T
authors.lastname: Sakurai
authors.forename: S
authors.initials: S
authors.lastname: Shioda
mesh_terms: D000818:Animals; D001069:Appetite Regulation / Q000502:physiology; D001921:Brain / Q000378:metabolism; D004435:Eating / Q000187:drug effects; D005215:Fasting / Q000378:metabolism*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D005260:Female; D006054:Goldfish / Q000235:genetics / Q000502:physiology*; D007276:Injections, Intraventricular; D047908:Intracellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000235:genetics / Q000502:physiology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D009479:Neuropeptides / Q000008:administration & dosage / Q000235:genetics / Q000502:physiology*; D000068797:Orexins; D012333:RNA, Messenger / Q000032:analysis
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D012333:RNA, Messenger