title: Spaceflight modulates insulin-like growth factor binding proteins and glucocorticoid receptor in osteoblasts.
abstract: Rat osteoblasts were cultured for 4 or 5 days during a Space Shuttle mission. After 20-h treatment with 1alpha,25-dihydroxyvitamin D3, conditioned media were harvested and cellular DNA and/or RNA were fixed on board. The insulin-like growth factor binding protein (IGF BP)-3 levels in the media were three- and tenfold higher than in ground controls on the fourth and fifth flight days, as quantitated by Western ligand blotting and radioimmunoassay, respectively. The increased IGF BP-3 protein levels correlated with two- to threefold elevation of IGF BP-3 mRNA levels, obtained by reverse transcription-polymerase chain reaction. The IGF BP-5 mRNA levels in flight cultures were 33-69% lower than in ground controls. The IGF BP-4 mRNA levels in flight cultures were 75% lower than in ground controls on the fifth day but were not different on the fourth day. The glucocorticoid receptor mRNA levels in flight cultures were increased by three- to eightfold on the fourth and fifth days compared with levels in ground controls. These data suggest potential mechanisms underlying spaceflight-induced osteopenia.
authors.affiliation: Faculty of Dentistry, Tokyo Medical and Dental University, Tokyo 113-8549, Japan. kumei.det2@dent.tmd.ac.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Kumei
authors.forename: H
authors.initials: H
authors.lastname: Shimokawa
authors.forename: H
authors.initials: H
authors.lastname: Katano
authors.forename: H
authors.initials: H
authors.lastname: Akiyama
authors.forename: M
authors.initials: M
authors.lastname: Hirano
authors.forename: C
authors.initials: C
authors.lastname: Mukai
authors.forename: S
authors.initials: S
authors.lastname: Nagaoka
authors.forename: P A
authors.initials: PA
authors.lastname: Whitson
authors.forename: C F
authors.initials: CF
authors.lastname: Sams
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D018969:Insulin-Like Growth Factor Binding Proteins / Q000096:biosynthesis / Q000378:metabolism*; D008297:Male; D010006:Osteoblasts / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D013026:Space Flight; D014893:Weightlessness / Q000009:adverse effects*
chemical_list: D018969:Insulin-Like Growth Factor Binding Proteins; D012333:RNA, Messenger; D011965:Receptors, Glucocorticoid; D004247:DNA