Regulation of food intake in the goldfish by interaction between ghrelin and orexin.
Intracerebroventricular (ICV) administration of ghrelin, orexin and neuropeptide Y (NPY) stimulates food intake in goldfish. Orexin and NPY interact with each other in the regulation of feeding, while ghrelin-induced feeding has also shown to be mediated by NPY in the goldfish model. To investigate the interaction between ghrelin and orexin, we examined the effects of a selective orexin receptor-1 antagonist, SB334867, and a growth hormone secretagogue-receptor antagonist, [D-Lys(3)]-GHRP-6, on ghrelin- and orexin-A-induced feeding. Ghrelin-induced food intake was completely inhibited for 1h following ICV preinjection of SB334867, while [D-Lys(3)]-GHRP-6 attenuated orexin-A stimulated feeding. Furthermore, ICV administration of ghrelin or orexin-A at a dose sufficient to stimulate food intake increased the expression of each other's mRNA in the diencephalon. These results indicate that, in goldfish, ghrelin and orexin-A have interacting orexigenic effects in the central nervous system. This is the first report that orexin-A-induced feeding is mediated by the ghrelin signaling in any animal model.
Miura
Tohru
T
Laboratory of Regulatory Biology, Graduate School of Science and Engineering, University of Toyama, 3190-Gofuku, Toyama 930-8555, Japan.
Maruyama
Keisuke
K
Shimakura
Sei-Ichi
S
Kaiya
Hiroyuki
H
Uchiyama
Minoru
M
Kangawa
Kenji
K
Shioda
Seiji
S
Matsuda
Kouhei
K
D000818:Animals; D004435:Eating; D054439:Ghrelin; D006054:Goldfish; D007276:Injections, Intraventricular; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D009479:Neuropeptides / Q000378:metabolism*; D064446:Orexin Receptors; D000068797:Orexins; D036361:Peptide Hormones / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors*; D054440:Receptors, Ghrelin; D018013:Receptors, Neuropeptide / Q000037:antagonists & inhibitors*
D054439:Ghrelin; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D036361:Peptide Hormones; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; D054440:Receptors, Ghrelin; D018013:Receptors, Neuropeptide