title: Leptin prevents the fall in plasma osteocalcin during starvation in male mice.
abstract: Plasma osteocalcin, a marker of osteoblastic activity, is reduced in starvation, malnutrition, and anorexia nervosa, resulting in low bone turnover osteoporosis. Contradictory findings about the role of leptin as a link between nutritional status and bone physiology have been reported. We demonstrate that leptin-deficient ob/ob and leptin-resistant db/db male mice have increased plasma osteocalcin, and that in male ob/ob mice osteocalcin is not decreased by starvation, unlike control mice. Intraperitoneal leptin administration increased plasma osteocalcin in male ob/ob mice, and prevented its fall during 24h fasting and 5 days of food restriction in normal male mice. This effect may be mediated via actions on the hypothalamic-pituitary-testicular or -growth hormone axes, or a direct action on osteoblasts. These studies support the hypothesis that the fall in leptin during starvation and weight loss is responsible for the associated reduction in osteoblast activity, and suggest a role for leptin in regulating bone turnover.
authors.affiliation: Endocrine Unit, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK. tgoldstone@yahoo.com
authors.forename: A P
authors.initials: AP
authors.lastname: Goldstone
authors.forename: J K
authors.initials: JK
authors.lastname: Howard
authors.forename: G M
authors.initials: GM
authors.lastname: Lord
authors.forename: M A
authors.initials: MA
authors.lastname: Ghatei
authors.forename: J V
authors.initials: JV
authors.lastname: Gardiner
authors.forename: Z L
authors.initials: ZL
authors.lastname: Wang
authors.forename: R M
authors.initials: RM
authors.lastname: Wang
authors.forename: S I
authors.initials: SI
authors.lastname: Girgis
authors.forename: C J
authors.initials: CJ
authors.lastname: Bailey
authors.forename: S R
authors.initials: SR
authors.lastname: Bloom
mesh_terms: D000818:Animals; D020738:Leptin / Q000235:genetics / Q000494:pharmacology* / Q000502:physiology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009765:Obesity / Q000235:genetics; D015675:Osteocalcin / Q000097:blood*; D010907:Pituitary Hormones / Q000097:blood; D013217:Starvation
chemical_list: D020738:Leptin; D010907:Pituitary Hormones; D015675:Osteocalcin