Effect of clomiphene treatment on the human testicular response to a single dose of hCG

The effect of antioestrogen treatment on the human testicular response to hCG was investigated in 17 adult men to further clarify the role of endogenous oestradiol in the regulation of testicular steroidogenesis. Clomiphene citrate was administered in 2 different modes. Group 1 (n = 8) was treated for 6 days (100 mg of the antioestrogen once a day) and a single dose of hCG (5000 IU im) was given at the beginning of the experiment. In group 2 (n = 9), the treatment was started 7 days prior to the hCG injection and was continued for additional 6 days. In both groups peripheral blood samples were collected up to 6 days after hCG, and the sera were analysed for FSH, prolactin and 8 steroids. In group 1, the steroidogenic response was identical to that found previously in untreated men. In group 2, the 7-day treatment with clomiphene citrate led to elevated serum concentrations of LH, FSH, pregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, testosterone, 5α-dihydrotestosterone and oestradiol. When compared with these elevated values, the responses of serum 17-hydroxyprogesterone. dehydroepiandrosterone, androstenedione and testosterone to hCG were diminished. The ratios of the steroid concentrations support previous reports that hCG-induced inhibition of 17-hydroxylase, 17–20 desmolase and 3β-hydroxysteroid dehydrogenase-Δ^4–5 isomerase is decreased during antioestrogen administration. This further substantiates the idea of a central role for endogenous testicular oestradiol in the mediation of steroidogenic lesions following acute large doses of hCG.