A comparison of metabolism of progesterone to 5α-steroids in monkey, mouse and rat ovaries

Abstract Ovarian homogenates from suckling, immature and adult rhesus monkeys and mice and also those from immature rats were incubated with [ 3 H]-progesterone and NADPH. After incubation, the radioactive products were separated and identified by column and paper chromatography with derivative formation and recrystallization to constant specific activity. All ovaries from monkeys and mice of different ages converted 10–80% of progesterone to 17-hydroxy-4-pregnene-3,20-dione, androstenedion, testosterone, 20α-hydroxy-4-pregnen-3-one and/or 16α-hydroxy-4-pregnene-3,20-dione. In monkeys, however, all ovaries of different ages tested in the present study formed no 5α-reduced metabolites of these 4-ene-3-ketosteroids. In mice, ovaries at 2 and 10 weeks of age were unable to form 52-reduced C 21 -17-OH- and C 19 -steroids. whereas those at 3 and 4 weeks of age formed significant amounts of these 5α-products. In contrast to immature rats, immature ovaries of monkeys do not form significant amounts of 5α-reduced C 19 -steroids. Although immature ovaries of mice synthesize 5α-reduced C 19 -steroids from progesterone, this age dependent formation of 5α-steroids is less active than that in rats.