Testosterone-Induced Inhibition of the LH and FSH Responses to Gonadotropin-Releasing Hormone Occurs Slowly

Evidence for Decreased Secretion of Gonadotropin-Releasing Hormone in Pubertal Boys during Short-Term Testosterone Treatment

“…However, other observations did not lead us to expect to find a major reduction in pituitary responses to GnRH in this study, even if GnRH secretion were decreased markedly by sex steroids (23,24). For example, we demonstrated previously that abrupt withdrawal of pulsatile GnRH therapy in GnRH-deficient patients leads to subsequent augmentation of pituitary responsiveness (23).…”

“…For example, we demonstrated previously that abrupt withdrawal of pulsatile GnRH therapy in GnRH-deficient patients leads to subsequent augmentation of pituitary responsiveness (23). Furthermore, Camino-Torres et al (24) demonstrated that T-induced inhibition of pituitary responses to GnRH occurs slowly, after several weeks.…”

“…CaminoTorres et al (24) administered either 50 or 200 mg of T enanthate to normal men weekly, for 8 wk. They found that serum T must be increased to 150% of the mean adult male value for 28 days before gonadotropin responses to GnRH are significantly decreased.…”

“…These combined observations suggest that an increase in testicular steroids over a period of 3% to 6 days, regulates LH secretion primarily by reducing GnRH pulse amplitude in both pubertal boys and men. However, as the effects of sex steroids are both time-and dose-dependent, it is important to emphasize that longer treatment with T might be expected to have direct and/ or indirect suppressive effects on pituitary responsiveness to GnRH (24).…”

Population Pharmacokinetic/Pharmacodynamic Modeling of Depot Testosterone Cypionate in Healthy Male Subjects

“…The LH concentration after a stimulation test was chosen as the PD marker in part because the response of LH to the stimulation test was different across all three TC dose groups. The lag between loss of basal and stimulated LH levels has been previously observed 25. The ability of exogenous testosterone administration to suppress LH release was incorporated into the PD model.…”