title: Ghrelin stimulates growth hormone secretion and food intake in aged rats.
abstract: Age-related decreases in energy expenditure have been associated with the loss of skeletal muscle and decline of food intake, possibly through a mechanism involving changes of growth hormone (GH) secretion and feeding behavior. Age-related declines of growth hormone secretion and food intake have been termed the somatopause and anorexia of ageing, respectively. Ghrelin, a 28-amino-acid peptide, was isolated from human and rat stomachs as an endogenous ligand of growth hormone secretagogue receptor. Ghrelin stimulates growth hormone release and food intake when peripherally administered to rodents and humans. Here, we investigate the relationship between age-related decline of growth hormone secretion and/or food intake and ghrelin function. Ghrelin (10 nmol/kg body weight) was administered intravenously to male 3-, 12-, 24-and 27-month-old Long-Evans rats, after which growth hormone concentrations and 2 h food intake were measured. An intravenous administration of ghrelin to rats increased food intake in all generations. In addition, to orexigenic effect by ghrelin, intravenous administration of ghrelin elicited a marked increase in plasma GH levels, with the peak occurring 15 min after administration. These findings suggest that the aged rats maintain the reactivity to administered exogenous ghrelin.
authors.affiliation: Department of Internal Medicine, Miyazaki Medical College, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki, 889-1692, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Toshinai
authors.forename: Muhtashan S
authors.initials: MS
authors.lastname: Mondal
authors.forename: Takuya
authors.initials: T
authors.lastname: Shimbara
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Yukari
authors.initials: Y
authors.lastname: Date
authors.forename: Kenji
authors.initials: K
authors.lastname: Kangawa
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Nakazato
mesh_terms: D000367:Age Factors; D000375:Aging / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D004435:Eating / Q000187:drug effects*; D054439:Ghrelin; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D036361:Peptide Hormones / Q000494:pharmacology*; D051381:Rats; D020332:Rats, Inbred LEC
chemical_list: D054439:Ghrelin; D036361:Peptide Hormones; D013006:Growth Hormone