Aromatase inhibition by delta 1-testolactone does not relieve the gonadotropin-induced late steroidogenic block in normal men.
Aromatase inhibition by delta 1-testolactone [(17 oxa-D-homo 1,4 androstanediene-3,17 dione) 500 mg twice daily for 10 days] in nine normal men lowered circulating estradiol (E2) levels by about 25%, enhanced the secretion of FSH, 17-hydroxyprogesterone (17-OHP), and to a lesser degree testosterone (T), but did not affect serum LH levels. Despite E2 lowering there was greater accumulation of 17-OHP than of T after 7 days of treatment, suggesting 17,20-lyase inhibition. Unexpectedly, administration of delta 1-testolactone almost halved the T response to hCG (Pregnyl, 1500 IU), but did not affect the 17-OHP response. Thus, E2 lowering by testolactone aggravated the hCG-induced 17,20-lyase block present before testolactone administration. Although the present data might suggest that estrogens do not play a role in the genesis of the hCG-induced late steroidogenic block, the results suggest that testolactone per se, in addition to its reported antiestrogenic action, inhibits 17,20 lyase.
D019326:17-alpha-Hydroxyprogesterone; D000328:Adult; D001141:Aromatase / Q000494:pharmacology; D047072:Aromatase Inhibitors; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000097:blood*; D005640:Follicle Stimulating Hormone / Q000097:blood; D006062:Gonadotropins / Q000494:pharmacology*; D006801:Humans; D006908:Hydroxyprogesterones / Q000097:blood; D007985:Leydig Cells / Q000502:physiology*; D008297:Male; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D013738:Testolactone / Q000494:pharmacology*; D013739:Testosterone / Q000097:blood
D047072:Aromatase Inhibitors; D006063:Chorionic Gonadotropin; D006062:Gonadotropins; D006908:Hydroxyprogesterones; D013739:Testosterone; D004958:Estradiol; D019326:17-alpha-Hydroxyprogesterone; D013738:Testolactone; D005640:Follicle Stimulating Hormone; D010088:Oxidoreductases; D001141:Aromatase