Hepatic microsomal 16-alpha-hydroxylation of 3-beta-hydroxyandrost-5-en-17-one (DHA) by fetal, newborn, and adult rhesus monkeys

Endocrine and pharmacological factors which influence the onset of labour in rhesus monkeys

Indomethacin administration in late pregnancy prolonged gestation in caged rhesus monkeys and inhibited premature labour and postponed delivery in chronically catheterized monkey fetuses. Chronic indomethacin treatment was associated with a reduction in the urinary excretion of a prostaglandin metabolite, a potent inhibitory effect on myometrial cyclic AMP phosphodiesterase, and severe oligohydramnios in pre-term and post-term fetuses. Experimental anencephaly (functional hypophysectomy) of the rhesus fetus results in lowered concentrations of maternal oestradiol and loss of the precise control of gestational length, with 40% of fetuses delivering beyond term. Corticotropin (ACTH) infused into the fetus results in raised concentrations of fetal and maternal cortisol, progesterone and oestrogens. Progesterone concentrations in peripheral blood apparently have little bearing on uterine quiescence in the rhesus monkey, since the concentrations of progesterone in maternal and fetal blood vary directly with uterine activity. The results of chronic infusion of corticotropin in the fetal monkey support the theory that in the monkey parturition is mediated by increased oestrogen production by the fetoplacental unit and by a rise in the concentrations of oestrone and prostaglandin in the amniotic fluid.

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.