The regulation of ovine placental steroid 17 alpha-hydroxylase and aromatase by glucocorticoid. 1988

J T France, and R R Magness, and B A Murry, and C R Rosenfeld, and J I Mason
Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75235.

Parturition in the pregnant sheep is preceded by an abrupt alteration in placental steroid metabolism causing a shift from progesterone to estrogen production. This change is believed to be a consequence of the prepartum rise in cortisol in the fetal circulation and involves increases in activities of the enzymes steroid 17 alpha-hydroxylase (cytochrome P-450(17)alpha), steroid C-17,20-lyase, and possibly aromatase. We have investigated the activity levels of aromatase and 17 alpha-hydroxylase in placental microsomes in late pregnancy and dexamethasone-induced labor. Over the gestational period of 118-140 days basal levels of placental aromatase were relatively constant [mean value (+/- SD) of 5.6 +/- 1.6 pmol min-1 mg microsomal protein-1 (n = 10)]. Steroid 17 alpha-hydroxylase activity was undetectable [less than 0.5 pmol min-1 mg microsomal protein-1 (n = 7)]. In six animals in labor induced with infusion of dexamethasone into the fetus, placental aromatase activity had a mean value of 14.0 +/- 2.5 pmol min-1 mg protein-1; placental steroid 17 alpha-hydroxylase, measured in four of the animals, had a mean (+/- SD) activity of 319 +/- 58 pmol min-1 mg microsomal protein-1. Immunoblotting of placental microsomal preparations with specific antibodies to cytochrome P-450(17)alpha and NADPH-cytochrome P-450-reductase indicated that the glucocorticoid-induced activity of 17 alpha-hydroxylase was associated with increased content of cytochrome P-450(17)alpha. Northern blotting with a cDNA probe for cytochrome P-450(17)alpha showed that glucocorticoid increased the levels of mRNA for the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

UI MeSH Term Description Entries
D008861 Microsomes Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed) Microsome
D009251 NADPH-Ferrihemoprotein Reductase A flavoprotein that catalyzes the reduction of heme-thiolate-dependent monooxygenases and is part of the microsomal hydroxylating system. EC 1.6.2.4. Cytochrome P-450 Reductase,Ferrihemoprotein P-450 Reductase,NADPH Cytochrome P-450 Oxidoreductase,NADPH Cytochrome P-450 Reductase,NADPH Cytochrome c Reductase,Cytochrome P-450 Oxidase,Cytochrome P450 Reductase,Ferrihemoprotein P450 Reductase,NADPH Cytochrome P450 Oxidoreductase,NADPH Cytochrome P450 Reductase,NADPH-Cytochrome P450 Reductase,NADPH-P450 Reductase,Cytochrome P 450 Oxidase,Cytochrome P 450 Reductase,Ferrihemoprotein P 450 Reductase,NADPH Cytochrome P 450 Oxidoreductase,NADPH Cytochrome P 450 Reductase,NADPH Ferrihemoprotein Reductase,NADPH P450 Reductase,Oxidase, Cytochrome P-450,P-450 Oxidase, Cytochrome,P450 Reductase, Cytochrome,P450 Reductase, NADPH-Cytochrome,Reductase, Cytochrome P-450,Reductase, Cytochrome P450,Reductase, Ferrihemoprotein P-450,Reductase, Ferrihemoprotein P450,Reductase, NADPH-Cytochrome P450,Reductase, NADPH-Ferrihemoprotein,Reductase, NADPH-P450
D010920 Placenta A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products. It includes a fetal portion (CHORIONIC VILLI) derived from TROPHOBLASTS and a maternal portion (DECIDUA) derived from the uterine ENDOMETRIUM. The placenta produces an array of steroid, protein and peptide hormones (PLACENTAL HORMONES). Placentoma, Normal,Placentome,Placentas,Placentomes
D011247 Pregnancy The status during which female mammals carry their developing young (EMBRYOS or FETUSES) in utero before birth, beginning from FERTILIZATION to BIRTH. Gestation,Pregnancies
D011270 Pregnancy, Animal The process of bearing developing young (EMBRYOS or FETUSES) in utero in non-human mammals, beginning from FERTILIZATION to BIRTH. Animal Pregnancies,Animal Pregnancy,Pregnancies, Animal
D005260 Female Females
D005938 Glucocorticoids A group of CORTICOSTEROIDS that affect carbohydrate metabolism (GLUCONEOGENESIS, liver glycogen deposition, elevation of BLOOD SUGAR), inhibit ADRENOCORTICOTROPIC HORMONE secretion, and possess pronounced anti-inflammatory activity. They also play a role in fat and protein metabolism, maintenance of arterial blood pressure, alteration of the connective tissue response to injury, reduction in the number of circulating lymphocytes, and functioning of the central nervous system. Glucocorticoid,Glucocorticoid Effect,Glucorticoid Effects,Effect, Glucocorticoid,Effects, Glucorticoid
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001141 Aromatase An enzyme that catalyzes the desaturation (aromatization) of the ring A of C19 androgens and converts them to C18 estrogens. In this process, the 19-methyl is removed. This enzyme is membrane-bound, located in the endoplasmic reticulum of estrogen-producing cells of ovaries, placenta, testes, adipose, and brain tissues. Aromatase is encoded by the CYP19 gene, and functions in complex with NADPH-FERRIHEMOPROTEIN REDUCTASE in the cytochrome P-450 system. CYP19,Cytochrome P-450 CYP19,Cytochrome P-450(AROM),Androstenedione Aromatase,CYP 19,CYP19 Protein,Cytochrome P450 19,Estrogen Synthase,Estrogen Synthetase,P450AROM,Aromatase, Androstenedione,Cytochrome P 450 CYP19,Protein, CYP19
D012756 Sheep Any of the ruminant mammals with curved horns in the genus Ovis, family Bovidae. They possess lachrymal grooves and interdigital glands, which are absent in GOATS. Ovis,Sheep, Dall,Dall Sheep,Ovis dalli

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