Nocturnal serum growth hormone concentration is not augmented by short-term testosterone infusion in pubertal boys

Chronic exposure to testosterone (T) increases growth hormone (GH) secretion. To determine whether acute exposure to T would also enhance GH secretion, we infused saline, followed 1 wk later by T, for 18-24 h at one-third the adult male production rate in 12 pubertal boys and at the adult male production rate in eight additional pubertal boys. Blood was obtained every 20 min for GH and every 30 min for T from 2000-0800 h. Though infusion significantly increased serum T concentrations in all 20 boys, mean GH concentration, GH pulse frequency, and GH pulse amplitude did not increase compared to the saline infusion night. The secretory dynamics of GH as a function of 3-h time blocks from 2000-0800 h were also determined in the eight boys who received the higher dose of T. The profile for mean GH concentration, pulse frequency, pulse amplitude, and peak area were not affected by acute infusion of T at concentrations sufficient to alter LH secretion. This suggests that, at least in pubertal boys, one must be exposed to T for a period longer than 12-18 h to induce increased GH secretion.