1. Formation of steroids by the pregnant mare. V. Metabolism of 14C-isopentenylpyrophosphate and 3H-dehydroisoandrosterone injected into the fetus.
- Author
-
Bhavnani BR, Martin LJ, and Baker RD
- Subjects
- 17-Ketosteroids biosynthesis, 17-Ketosteroids urine, Alkenes metabolism, Animals, Estradiol urine, Estranes urine, Estrogens urine, Estrone urine, Female, Hydroxysteroids urine, Phenols, Phosphoric Acids metabolism, Pregnancy, Pregnanediol urine, Pregnanes urine, Dehydroepiandrosterone metabolism, Estranes biosynthesis, Horses metabolism, Maternal-Fetal Exchange, Organophosphorus Compounds metabolism, Pregnancy, Animal
- Abstract
A mixture of 1-14C-isopentenylpyrophosphate and 3H-dehydroisoandrosterone was injected into a horse fetus intramuscularly during laparotomy, after which maternal urine was collected for 4 days. Steroid conjugates in the urine were extracted with Amberlite XAD-2 resin, hydrolysed and separated into phenolic and neutral fractions. From the phenolic fraction estrone, 17alpha-estradiol, equilin and equilenin were isolated. Only estrone and 17alpha-estradiol contained both 3H and 14C, while the ring B unsaturated estrogens contained only 14C. From the neutral fraction 14C-labeled 3beta-hydroxy-5alpha-pregnan-20-one, 5alpha-pregnane-3beta,20beta-diol and 5alpha-pregnan-3beta, 20alpha-diol were isolated. These results demonstrate that the route of biosynthesis of both the ring B saturated and unsaturated estrogens is the same up to the stage of isopentenylpyrophosphate. Thus, the bifurcation in the classical pathway of steroid biosynthesis reported previously by us is occurring at a point after the formation of isopentenylpyrophosphate and prior to the formation of squalene.
- Published
- 1975
- Full Text
- View/download PDF