Recombinant Human Follicle-Stimulating Hormone Administration Increases Testosterone Production in Men, Possibly by a Sertoli Cell-Secreted Nonsteroid Factor

We previously showed that recombinant human FSH (R-FSH) in males increased the testosterone (T) concentration in spermatic venous blood (SB). To investigate the effect of R-FSH on spermatic steroid levels and the action of steroid- and LH-free SB on isolated Leydig cells, nine normospermic males were studied during spermatic cord surgery. Peripheral blood and SB samples were collected before and 30 min after iv administration of 150 U R-FSH to measure LH, FSH, T, estradiol, 17α-hydroxyprogesterone, and sex hormone-binding globulin, and in SB, androstenedione (Δ4) and dehydroepiandrosterone (DHEA) were also measured. LH bioactivity was assessed by in vitro production of T in isolated Leydig cells. The actions of R-FSH and SB (steroid and LH free) were analyzed in the bioassay. Data are expressed as the mean ± se. FSH in peripheral blood and SB increased by 411% and 477% after R-FSH administration. R-FSH induced a significant increase in spermatic T (basal vs. 30 min, 326.4 ± 98.5 vs. 732.4 ± 152.8 ng/mL; P...