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| Testosterone dose-response relationships in healthy young men |
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| Author(s): Bhasin S, Woodhouse L, Casaburi R, Singh AB, Bhasin D, Berman N, Chen XH, Yarasheski KE, Magliano L, Dzekov C, Dzekov J, Bross R, Phillips J, Sinha-Hikim I, Shen RQ, Storer TW |
| Source: AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM Volume: 281 Issue: 6 Pages: E1172-E1181 Published: DEC 2001 |
| Times Cited: 107 References: 50 |
| Abstract: Testosterone increases muscle mass and strength and regulates other physiological processes, but we do not know whether testosterone effects are dose dependent and whether dose requirements for maintaining various androgen-dependent processes are similar. To determine the effects of graded doses of testosterone on body composition, muscle size, strength, power, sexual and cognitive functions, prostate-specific antigen (PSA), plasma lipids, hemoglobin, and insulin-like growth factor I (IGF-I) levels, 61 eugonadal men, 18-35 yr, were randomized to one of five groups to receive monthly injections of a long-acting gonadotropin-releasing hormone (GnRH) agonist, to suppress endogenous testosterone secretion, and weekly injections of 25, 50, 125, 300, or 600 mg of testosterone enanthate for 20 wk. Energy and protein intakes were standardized. The administration of the GnRH agonist plus graded doses of testosterone resulted in mean nadir testosterone concentrations of 253, 306, 542, 1,345, and 2,370 ng/dl at the 25-, 50-, 125-, 300-, and 600-mg doses, respectively. Fat-free mass increased dose dependently in men receiving 125, 300, or 600 mg of testosterone weekly (change +3.4, 5.2, and 7.9 kg, respectively). The changes in fat-free mass were highly dependent on testosterone dose (P = 0.0001) and correlated with log testosterone concentrations (r = 0.73, P = 0.0001). Changes in leg press strength, leg power, thigh and quadriceps muscle volumes, hemoglobin, and IGF-I were positively correlated with testosterone concentrations, whereas changes in fat mass and plasma high-density lipoprotein (HDL) cholesterol were negatively correlated. Sexual function, visual-spatial cognition and mood, and PSA levels did not change significantly at any dose. We conclude that changes in circulating testosterone concentrations, induced by GnRH agonist and testosterone administration, are associated with testosterone dose- and concentration-dependent changes in fat-free mass, muscle size, strength and power, fat mass, hemoglobin, HDL cholesterol, and IGF-I levels, in conformity with a single linear dose- response relationship. However, different androgen-dependent processes have different testosterone dose- response relationships. |
| Document Type: Article |
| Language: English |
| Reprint Address: Bhasin, S (reprint author), Univ Calif Los Angeles, Sch Med, 1731 E 120th St, Los Angeles, CA 90059 USA |
Addresses:
1. Charles R Drew Univ Med & Sci, Div Endocrinol Metab & Mol Med, Los Angeles, CA 90059 USA
2. Univ Calif Los Angeles, Los Angeles Cty Harbor Med Ctr, Torrance, CA 90502 USA
3. El Camino Coll, Lab Exercise Sci, Torrance, CA 90502 USA
4. Washington Univ, Dept Internal Med, St Louis, MO 63110 USA |
| Publisher: AMER PHYSIOLOGICAL SOC, 9650 ROCKVILLE PIKE, BETHESDA, MD 20814 USA |
| Subject Category: Endocrinology & Metabolism; Physiology |
| IDS Number: 490JA |
| ISSN: 0193-1849 |
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