Regulation by Growth Hormone of Number of Chondrocytes Containing IGF-I in Rat Growth Plate

• DOI: 10.1126/science.3523759
• Publication Date: 2006-10-05T20:28:52Z
• Authors: Anders Nilsson; Jörgen Isgaard; Anders Lindahl; Annica Dahlström; Anna Skottner; Olle G. P. Isaksson
• Keywords: Hypophysectomy; Somatomedin; Epiphyseal plate

Whether growth hormone stimulates longitudinal bone by a direct effect at the site of plate or indirectly increasing concentration circulating somatomedins (insulin-like factors) has been subject controversy. Immunohistochemical methods were used to explore localization and distribution insulin-like factor I (IGF-I) immunoreactivity in epiphyseal proximal tibia male rats. Cells proliferative zone normal rats exhibited bright immunofluorescence, whereas cells germinal hypertrophic zones stained only weakly. In subjected hypophysectomy, number fluorescent was markedly reduced. When hypophysectomized treated with hormone, either systemically plate, IGF-I-immunoreactive increased. The results show that IGF-I is produced chondrocytes IGF-I-containing directly regulated hormone. These findings suggest specific role clonal expansion differentiated exerts its function locally through autocrine paracrine mechanisms.