Conversion,in vitro,of (7n-3H) testosterone to estrone and estradiol-17β and their 3-sulfäte conjugate by the guinea-pig placenta

Different cellular fractions of guinea-pig placenta were incubated in the presence of (7n-³H) testosterone. Microsomal aromatization of ³H-testosterone into estrone and estradiol-17β was demonstrated in the presence of NADPH. The predominance of estrone after incubation with 17β-hydroxylated precursors, (7n-³H) testosterone and (6,7-³H) estradiol-17β, indicate that there is a microsomal 17β-hydroxysterold dehydrogenase activity. In this report, cytosolic sulfurylation of estrogens is demonstrated. This latter activity represents a quite original characteristic of the placental metabolism of estrogens in guinea-pigs. In contrast with the human placenta where there is considerable sulfatase activity, the guinea-pig placenta can sulfurylate estrogens.