Growth hormone has no direct effect on human adrenal steroid and insulin-like growth factor-binding protein secretion.
Although it is known that growth hormone (GH) exerts its growth-promoting effects mainly via Insulin-like growth factor-I (IGF-I), an increasing number of direct effects of GH has been described in many tissues. In vivo, mice transgenic for human growth hormone (hGH) show significantly elevated levels of corticosterone, enlarged adrenal glands, and altered levels of insulin-like growth factor binding proteins (IGF-BPs). Recently, we have shown that IGF's induce the secretion of cortisol and IGF-BP's in adult human adrenocortical cells. However, since human adrenal glands express the intact GH-receptor, the objective of this study was to investigate whether GH exerts a direct effect on the steroidogenesis and IGF-BP synthesis in adult human adrenocortical cells. Primary cell cultures in monolayer were incubated under serum-free conditions with human growth hormone and/or ACTH for up to 72 hours. Cortisol was measured by specific RIA and the secretion of insulin-like growth factor binding proteins was analyzed by Western ligand blotting. hGH alone was unable to stimulate basal or ACTH-induced cortisol secretion. Additionally, neither hGH alone or in combination with ACTH did significantly alter the secretion of IGF-BP's. Therefore we conclude that hGH is unable to directly stimulate cortisol secretion and IGF-BP secretion in cultured human adrenocortical cells.
Michl
P
P
Department of Medicine II, Klinikum Grosshadern, University of Munich, Germany.
Engelhardt
D
D
Oberneder
R
R
Weber
M M
MM
D000302:Adrenal Cortex / Q000187:drug effects / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D015153:Blotting, Western; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D006854:Hydrocortisone / Q000096:biosynthesis / Q000378:metabolism*; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D007700:Kinetics
D016895:Culture Media, Serum-Free; D018969:Insulin-Like Growth Factor Binding Proteins; D019382:Human Growth Hormone; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone