Metabolism of progesterone in uterine tissue of non-pregnant rats in vitro.
The metabolism of labelled progesterone was studied in vitro in uterine tissue of non-pregnant rats with particular emphasis on the influence of substrate concentration. Neither a qualitative nor quantitative difference was found for a steroid tissue ratio between 15 X 10(-6) and 4.2 X 10(-9) to 1 g (substrate amounts between 57.73 and 0.02 nmol); with both concentrations 42 to 44 per cent of progesterone was metabolized to about 35 per cent monohydroxymonoketonic steroids and 4-6 per cent dihydroxylated C21O2-compounds. In both sets of incubations we have isolated and identified the following steroids: 3alpha-hydroxy-5alpha-pregnan-20-one, 3beta-hydroxy-4-pregnen-20-one, 3alpha-hydroxy-4-pregnen-20-one, 20alpha-hydroxy-4-pregnen-3-one, 5alpha-pregnane-3alpha,20alpha-diol and 4-pregnene-3alpha,20alpha-diol. The most abundant metabolite formed in these incubations was 3alpha-hydroxy-4-pregnen-20-one which corresponds to about 30 per cent of the total activity recovered. It is the first time that the presence of 20alpha-hydroxysteroid-oxidoreductase activity is definitely established in this type of tissue. The identification of three allylic alcohols as progesterone metabolites in the rat uterus confirms that delta4-3-hydroxysteroids are important intermediates in the in vitro uterine metabolism of steroids.
D004092:20-alpha-Dihydroprogesterone / Q000096:biosynthesis; D000498:Allyl Compounds; D000818:Animals; D005260:Female; D011276:Pregnanediol / Q000096:biosynthesis; D011278:Pregnanes / Q000096:biosynthesis; D011280:Pregnanolone / Q000096:biosynthesis; D011283:Pregnenes / Q000096:biosynthesis; D011374:Progesterone / Q000378:metabolism*; D051381:Rats; D014599:Uterus / Q000378:metabolism*
D000498:Allyl Compounds; D011278:Pregnanes; D011283:Pregnenes; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D011280:Pregnanolone; D011276:Pregnanediol