title: Insulin-like growth factor-II increases plasma osteocalcin concentration in newborn lambs.
abstract: The influence of GH, IGF-I and IGF-II on plasma 1,25-(OH)2D and osteocalcin (OC) concentrations was studied in four groups of five newborn lambs each. They received a single i.v. injection of either purified bovine GH (1 IU/mg 600 micrograms/kg body wt), synthetic human IGF-I (10 or 200 micrograms/kg body wt) or synthetic human IGF-II (10 micrograms/kg body wt). Five controls were injected the same volume (1 ml) of solvent. IGF-II, but not GH or IGF-I, induced a rapid (1.5 h) and sustained (up to 18 h) increase of serum osteocalcin. This effect of IGF-II on plasma OC concentration was not mediated by 1,25-(OH)2D, which increased in plasma only 18 h after IGF-II injection. These data suggest that IGF-II stimulates, the in vivo secretion of OC by osteoblasts through a mechanism independent of 1,25-(OH)2D. Further studies are necessary to elucidate the mechanism of IGF-II action on osteocalcin synthesis and to explain the late increase of plasma 1,25-(OH)2D after IGF-II injection.
authors.affiliation: INRA Theix, St Genès-Champanelle, France.
authors.forename: V
authors.initials: V
authors.lastname: Coxam
authors.forename: M J
authors.initials: MJ
authors.lastname: Davicco
authors.forename: P
authors.initials: P
authors.lastname: Pastoureau
authors.forename: P D
authors.initials: PD
authors.lastname: Delmas
authors.forename: J P
authors.initials: JP
authors.lastname: Barlet
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000097:blood*; D002117:Calcitriol / Q000097:blood; D013006:Growth Hormone / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D008297:Male; D015675:Osteocalcin / Q000097:blood*; D011863:Radioimmunoassay; D012756:Sheep / Q000097:blood*
chemical_list: D015675:Osteocalcin; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone; D002117:Calcitriol