Androgen metabolism by hepatic and renal tissues of the fetal rhesus monkey

Liver and kidney from fetal monkeys (day 125 of gestation) were fractionated into low speed pellets, microsomal and cytosolic fractions. Liver cytosols converted as much testosterone (T) to 5 beta-androstane-3 alpha,17 beta-diol (5 beta-diol) at 0 degrees C as at 4 degrees-45 degrees C without exogenous cofactors. The principal product formed from 5 alpha-dihydrotestosterone (5 alpha-DHT) was 5 alpha-diol. A 1000-fold molar excess of radioinert 5 beta- or 5 alpha-DHT inhibited 5 beta-diol formation from 3H]T by cytosols and increased 5 beta-DHT formation. Similarly, using 5 alpha-DHT as substrate, 5 alpha-diol formation was inhibited. Microsomal and low speed pellets with added cofactors formed products which recrystallized with either etiocholanolone or androsterone from 3H]T or 3H]DHT, respectively. Little product was formed without cofactor. Whole liver homogenates produced 5 beta-reduced products from 3H]T in the presence of an NADPH generating system whereas kidney homogenates produced 5 alpha-reduced products. These data provide new information on the capacity of fetal monkey liver and kidney to metabolize androgens. The 3 alpha-reductases are cytosolic. The 5 alpha- and 5 beta-reductases are mostly in the low speed pellet but are sufficiently represented in cytosols to mediate diol formation. The 17-hydroxysteroid dehydrogenases are in the microsomal fraction. Our results suggest that 5 alpha-DHT is the active androgen in fetal liver since testosterone is metabolized to 5 beta-DHT and 5 beta-diol which are inactive androgens.