Effect of testosterone on somatomedin-C concentrations in prepubertal boys

• Published in: The journal of clinical endocrinology and metabolism Vol. 58; no. 1; p. 87
• Main Authors: Parker, M W, Johanson, A J, Rogol, A D, Kaiser, D L, Blizzard, R M
• Format: Journal Article
• Language: English
• Published: United States 01.01.1984
• Subjects: Adolescent; Adult; Child; Child, Preschool; Growth Hormone - deficiency; Growth Hormone - pharmacology; Growth Hormone - therapeutic use; Humans; Insulin-Like Growth Factor I; Male; Puberty, Delayed - blood; Puberty, Delayed - drug therapy; Somatomedins - blood; Testosterone - pharmacology; Testosterone - therapeutic use
• ISSN: 0021-972X; 1945-7197
• DOI: 10.1210/jcem-58-1-87

To investigate the role of testosterone (T) in the pubertal elevation of somatomedin-C (SmC), six prepubertal GH-deficient boys were each given 7-day courses of GH alone (0.05 U/kg X day, im), T alone (T propionate; 25 mg/day, im), and a combination of GH and T at the same dosages. Plasma SmC levels were determined on samples drawn at the start and finish of each period, and each course was separated by a 7-day period. SmC was also measured before and after a course of T propionate (25 mg/day, im) in four GH-sufficient boys with delayed adolescence. In the GH-deficient boys, GH and the combination of GH and T resulted in comparable and significant increments of SmC (mean change, 0.68 U/ml after GH and 0.63 U/ml after the combination of GH and T). T alone caused no change in SmC in the GH-deficient boys (mean change, 0.09 U/ml), but resulted in increases in all four GH-sufficient subjects (mean change, 1.29 U/ml). In a single subject with constitutionally delayed puberty, the integrated 24-h GH concentration rose from 2.8 ng/ml before to 5.8 ng/ml after T therapy. Both the number and amplitude of GH secretory events were greater after therapy. These data show that T stimulates SmC production in prepubertal boys who can secrete GH, but not in those who are GH deficient. We postulate that the effect of T in this regard is due to its effect on pituitary GH secretion. Although the T levels were within the pharmacological range, physiological levels of T (e.g. at puberty) may be responsible for the adolescent SmC increment in men.