Rapid and slow response of human testicular steroidogenesis to hCG by measurements of steroids in spermatic and peripheral vein blood.

The effects of human chorionic gonadotropin (hCG) on testicular steroid secretion were studied in men during operation upon inguinal hernia. To investigate the rapid testicular response, we drew blood samples from peripheral and spermatic veins at the beginning of the operation, then gave an intramuscular injection of 5000 I.U. of hCG, and took another set of blood samples 30 min after injection. The slow testicular response to hCG was evaluate by taking samples from spermatic and peripheral veins 4 days following hCG administration. The operation alone led to a significant decrease in spermatic vein levels of pregnenolone, progesterone, 17-hydroxyprogesterone, androstenedione and testosterone in 30 min. Testicular steroidogenesis responded rapidly to hCG stimulation, which was reflected in elevated spermatic vein levels of pregnenolone, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone and 5 alpha-dihydrotestosterone at 30 min following hCG. In peripheral vein, the concentrations of pregnenolone, progesterone and 17-hydroxyprogesterone were significantly elevated at the same time. Four days following hCG administration, the peripheral serum concentrations of 17-hydroxyprogesterone, testosterone, 5 alpha-dihydrotestosterone and estradiol were significantly increased. In spermatic vein, the steroids released after 4 days suggested a preferential release of C19 steroids and estradiol. Our results directly demonstrate that the human testis is able to respond rapidly to hCG stimulation. The first effect of hCG might be general facilitation of C21 and C19 steroid release to the circulation. Four days after hCG stimulation, the secretion of C19 steroids (including testosterone) and estradiol seems to be preferred, with a relative decrease in the release of C21 steroids.