Human chorionic gonadotropin and testicular function: stimulation of testosterone, testosterone precursors, and sperm production despite high estradiol levels.

Abstract

Excessive gonadotropin stimulation of the testis induced by the administration of high doses of hCG or LH markedly decreases testicular function in experimental animals. The adverse effects of supraphysiological gonadotropin stimulation are thought to be mediated, in part, by the very high levels of estradiol produced. We administered a supraphysiological dosage of hCG together with exogenous testosterone (T) to normal men for several months. The combination of these agents produced very high serum estradiol (E2) levels and (we assume) high intratesticular E2 levels. In this setting of supraphysiological gonadotropin stimulation and high E2 levels, we examined serum levels of T, the δ4 and δ5 steroid precursors of T, and sperm production. After a 3-month control period, five normal men received T enthanate (T; 200 mg, im, weekly) for 3–5 months. Then, while T was continued in the same dosage, all subjects were given hCG (5000 IU, im, three times weekly) for an additional 4–6 months. Serum E2 levels during...