OESTROGEN SYNTHESIS FROM [4-14C–1,2-3H]TESTOSTERONE BY PLACENTAL MICROSOMES FROM BABOONS

Abstract

SUMMARY Washed, lyophilized placental microsomes from baboons were incubated with [4-14C–1,2-3H]testosterone and NADPH in air; labelled oestrone, 17β-oestradiol, androstenedione, 19-hydroxytestosterone, 19-hydroxyandrostenedione and unchanged substrate were isolated from the incubations by paper chromatography and were further characterized by crystallization to constant specific activity. When NADPH was omitted, androstenedione was the only metabolite and its yield was greatly diminished. Oestrone and 17β-oestradiol had similar 3H: 14C ratios and the amount of tritium retained in these metabolites was about 28% of that present in the substrate. The amount of tritium retained in oestrone and 17β-oestradiol suggest that aromatization by the baboon placenta proceeds through the same pathway as that demonstrated for the human placenta. A slight decrease in the 3H:14C ratio was observed in androstenedione, 19-hydroxytestosterone and 19-hydroxyandrostenedione. The recovered substrate had an unchanged ratio.