RESUMO
The effect of androgens on the conversion of estradiol (E2) and estrone (E1) from estrone-3-sulfate (E1-S) was studied in explants of normal human term placentas. Explants incubated in medium supplemented with 2.0 microM E1-S showed that 50 microM dihydrotestosterone (DHT) stimulated E2 production 15-fold above control values after 0.5h, but neither 50 microM methyltestosterone (MT) nor 50 microM diethylstilbestrol (DES) had any effect. HCG (5.0 i.u./ml), alone or in combination with one of the androgens, did not influence the E2 production. When the explants were incubated in medium with 0.25 microM E1-S (the average concentration reported for late pregnancy plasma), DHT (0.5-50 microM) caused a dose- and time-dependent increase in E2 production, while E1 production and the combined accumulation of E2 and E1 were slightly inhibited by all doses of DHT during the 0.5-4h incubation. When E1 (0.1 microM) was used as substrate, DHT caused a dramatic dose- and time-dependent shift in the E1-E2 equilibrium towards E2. The results indicate that during late pregnancy, a particular class of androgens may increase the production of the more bioactive E2 from the circulating E1-S; the mode of action may be an enhanced conversion of E1 to E2.
