Growth hormone and testosterone interact positively to enhance protein and energy metabolism in hypopituitary men
Open Access
- 1 August 2005
- journal article
- clinical trial
- Published by American Physiological Society in American Journal of Physiology-Endocrinology and Metabolism
- Vol. 289 (2), E266-E271
- https://doi.org/10.1152/ajpendo.00483.2004
Abstract
We investigated the impact of growth hormone (GH) alone, testosterone (T) alone, and combined GH and T on whole body protein metabolism. Twelve hypopituitary men participated in two studies. Study 1 compared the effects of GH alone with GH plus T, and study 2 compared the effects of T alone with GH plus T. IGF-I, resting energy expenditure (REE), and fat oxidation (Fox) and rates of whole body leucine appearance (Ra), oxidation (Lox), and nonoxidative leucine disposal (NOLD) were measured. In study 1, GH treatment increased mean plasma IGF-I ( P < 0.001). GH did not change leucine Ra but reduced Lox ( P < 0.02) and increased NOLD ( P < 0.02). Addition of T resulted in an additional increase in IGF-I ( P < 0.05), reduction in Lox ( P < 0.002), and increase in NOLD ( P < 0.002). In study 2, T alone did not alter IGF-I levels. T alone did not change leucine Ra but reduced Lox ( P < 0.01) and increased NOLD ( P < 0.01). Addition of GH further reduced Lox ( P < 0.05) and increased NOLD ( P < 0.05). In both studies, combined treatments on REE and Fox were greater than either alone. In summary, GH-induced increase of circulating IGF-I is augmented by T, which does not increase IGF-I in the absence of GH. T and GH exerted independent and additive effects on protein metabolism, Fox and REE. The anabolic effects of T are independent of circulating IGF-I.Keywords
This publication has 40 references indexed in Scilit:
- How Is Whole Body Protein Turnover Perturbed in Growth Hormone-Deficient Adults?Journal of Clinical Endocrinology & Metabolism, 1998
- Growth Hormone (GH)-Deficient Men Are More Responsive to GH Replacement Therapy Than WomenJournal of Clinical Endocrinology & Metabolism, 1997
- The Effect of Recombinant Human Growth Hormone on Glucose and Leucine Metabolism in Cushing's SyndromeJournal of Clinical Endocrinology & Metabolism, 1997
- Do androgens regulate growth hormone-binding protein in adult man?Journal of Clinical Endocrinology & Metabolism, 1995
- Energy metabolism and substrate oxidation in acromegalyJournal of Clinical Endocrinology & Metabolism, 1995
- Adults with growth hormone deficiency have abnormal body composition but normal energy metabolismJournal of Clinical Endocrinology & Metabolism, 1995
- Diagnosis of growth-hormone deficiency in adultsThe Lancet, 1994
- Testosterone administration increases insulin-like growth factor-I levels in normal menJournal of Clinical Endocrinology & Metabolism, 1993
- Activation of the somatotropic axis by testosterone in adult males: evidence for the role of aromatizationJournal of Clinical Endocrinology & Metabolism, 1993
- Interrelation of the therapeutic effects of growth hormone and testosterone on growth in hypopituitarismThe Journal of Pediatrics, 1976