Effects of IGF-I, alone and in combination with 17 beta-oestradiol, on bone remodelling parameters in ovariectomised rats.
We studied the effects of recombinant human IGF-I (250 micrograms/day) and/or 17 beta-oestradiol (E2; 5 or 50 micrograms/kg/day), s.c., for 28 days, on plasma IGF-I and 1,25-(OH)2 vitamin D3 concentrations and on biochemical indices of bone remodelling (plasma osteocalcin, urinary pyridinolines) in 3 month-old rats that had been ovariectomised (OVX) 6 weeks before. Ten weeks after ovariectomy, plasma 1,25-(OH)2D3 was increased, but IGF-I and bone remodelling indices were within the normal range. RhIGF-I administration to OVX rats increased both IGF-I and 1,25-(OH)2D3 concentrations, as well as plasma osteocalcin and urinary pyridinoline excretion. By contrast, E2 decreased plasma IGF-I and 1,25-(OH)2D3 and the markers of bone remodelling. The combination of rhIGF-I and E2 resulted in intermediate effects. Multiple regression analysis showed that IGF-I correlated with plasma osteocalcin, and also with the urinary excretion of pyridinolines. The data shows that rhIGF-I stimulates bone remodelling in growing OVX rats, and that circulating IGF-I is a determinant of bone remodelling in vivo.
Verhaeghe
J
J
Laboratorium voor Experimentele Geneeskunde en Endocrinologie, Katholieke Universiteit Leuven, Belgium.
Van Herck
E
E
van Bree
R
R
Bouillon
R
R
D000596:Amino Acids / Q000652:urine; D000818:Animals; D015415:Biomarkers / Q000097:blood / Q000652:urine; D001786:Blood Glucose / Q000378:metabolism; D016723:Bone Remodeling / Q000187:drug effects / Q000502:physiology*; D002117:Calcitriol / Q000097:blood; D004347:Drug Interactions; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism / Q000494:pharmacology*; D015675:Osteocalcin / Q000097:blood; D010052:Ovariectomy; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000494:pharmacology; D012016:Reference Values
D000596:Amino Acids; D015415:Biomarkers; D001786:Blood Glucose; D011994:Recombinant Proteins; D015675:Osteocalcin; D004958:Estradiol; C015484:pyridinoline; D007334:Insulin-Like Growth Factor I; D002117:Calcitriol