TESTOSTERONE METABOLISM BY RAT PLACENTA

Testosterone-4-C14 was incubated with homogenates of 15- and 21- day rat placental tissue and the resulting radioactive metabolites more polar than testosterone were studied. The most abundantly occurring of these metabolites was shown to be identical to 5α-androstane-3α, 17β-diol, The presence of exogenous NADPH2 in incubations of 21-day placentas appeared to be necessary for the elaboration of this and other unidentified metabolites. Neither estrone nor estradiol were biosynthesized in detectable amounts from testosterone. The results suggest that both 15- and 21-day rat placental tissue homogenates have Δ4-reductase activity. In contrast to the human, rat placental tissue appears to be relatively deficient in aromatizing enzyme activity and perhaps in NADPH2 content. © 1968 Holden-Day, Inc.