title: Involvement of specific orexigenic neuropeptides in sweetener-induced overconsumption in rats.
abstract: Palatability is one of the factors that regulates food and fluid intake and contributes to overconsumption in turn contributing to obesity. To elucidate the brain mechanisms of the palatability-induced ingestion, we explored the roles of six hypothalamic orexigenic neuropeptides, orexin, melanin-concentrating hormone (MCH), neuropeptide Y (NPY), agouti-related protein (AgRP), ghrelin and dynorphin, in the intake of a palatable solution, saccharin. Of the six peptides, intracerebroventricular (i.c.v.) administrations of orexin, MCH and NPY increased the intake of saccharin. Drinking of saccharin in turn elevated the mRNA levels of orexin and NPY, but not MCH. Pre-treatments of naloxone, an opioid antagonist, blocked the orexigenic effects of orexin and NPY. Specific gastric motor responses induced by central orexin-A and NPY are well known, however, MCH did not induce such responses. The i.c.v. administration of orexin-A facilitated gastric emptying. These results suggest that the overconsumption promoted by sweet and palatable tastes is attributed to the activation of orexigenic neuropeptides, such as orexin and NPY, and a downstream opioid system together with enhanced digestive functions.
authors.affiliation: Department of Behavioral Physiology, Graduate School of Human Sciences, Osaka University, 1-2 Yamadaoka, Suita 565-0871, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Furudono
authors.forename: Chiho
authors.initials: C
authors.lastname: Ando
authors.forename: Chizuko
authors.initials: C
authors.lastname: Yamamoto
authors.forename: Motoi
authors.initials: M
authors.lastname: Kobashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
mesh_terms: D054369:Agouti-Related Protein; D000818:Animals; D001069:Appetite Regulation / Q000187:drug effects / Q000502:physiology*; D004399:Dynorphins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D005769:Gastrointestinal Motility / Q000502:physiology; D054439:Ghrelin; D006963:Hyperphagia / Q000139:chemically induced / Q000378:metabolism*; D007028:Hypothalamic Hormones / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D007276:Injections, Intraventricular; D036341:Intercellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D008297:Male; D008543:Melanins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D009479:Neuropeptides / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D000068797:Orexins; D036361:Peptide Hormones / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D010907:Pituitary Hormones / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013549:Sweetening Agents; D013649:Taste / Q000502:physiology*
chemical_list: C515197:AGRP protein, rat; D054369:Agouti-Related Protein; D054439:Ghrelin; C000596229:HCRT protein, human; D007028:Hypothalamic Hormones; D036341:Intercellular Signaling Peptides and Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009478:Neuropeptide Y; D009479:Neuropeptides; D000068797:Orexins; D036361:Peptide Hormones; D010907:Pituitary Hormones; D012333:RNA, Messenger; D013549:Sweetening Agents; C019463:melanin-concentrating hormone; D004399:Dynorphins