Abstract
SUMMARYNine adult healthy male volunteers were given a single intramuscular injection of 5000 iu of human chorionic gonadotrophin (hCG). Peripheral blood samples were collected up to 7 days after the injection, the sera were analysed for LH, FSH and prolactin and the results were related to changes in the concentrations of testosterone and oestradiol.Serum LH concentrations tended to decrease for 4 days after the hCG injection (to 65% of the 0 h value) but returned to the starting level during the 7‐day observation period. FSH was suppressed throughout the experiment and correlated inversely with serum prolactin (r = ‐0·74, P < 0·01). The first significant decrease was seen at 48 h and the minimum concentration (28 ± 4%, SEM) at 7 days. Prolactin levels changed only slightly during the first 48 h after the injection but increased thereafter, being significantly elevated at 4 days, and reached a maximum (183 ± 22%) at 6 days after hCG adminstration, coinciding with the late phase of the testosterone response to hCG. Between testosterone and prolactin a positive correlation (r = 0·70. P < 0·01) was found during hCG stimulation.The results suggest that endogenous steroid production of the human testis after hCG administration is sufficient to induce changes in gonadotrophin and prolactin secretion. It is further concluded that the feedback mechanism of FSH is more sensitive to increased testicular steroid output following hCG injection than that of LH. It is hypothesized that pituitary prolactin secretion is stimulated by the elevated serum oestradiol concentration at 24–48 h, and the long term testosterone response, observed 2–6 days after the hCG injection, may be partly due to increased prolactin concentrations.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call