Studies on oxidative phosphorylation and steroidogenesis by ovarian mitochondria after gonadotropic stimulation. 1976

M J Dimino, and D M Lloyd, and E A Elfont, and D W Peters, and R J Schubatis

No differences in oxidative phosphorylation or in the per cent of [4-14C]progesterone were found in ovarian mitochondria of immature rats after treatment with 20 IU of pregnant mare serum gonadotropin (PMSG) iv 30 min before killing. However, treatment of immature rats with 20 IU of PMSG sc 54 h prior to killing decreased the ADP:O ratio and increased the per cent of [4-14C]cholesterol conversion. Electron microscopic studies showed that mitochondria with lamellar cristae were prominent in ovaries of untreated rats, while large pleomorphic mitochondria and mitochondria with tubulovesicular cristae dominated in ovaries of PMSG-treated rats. Ovarian homogenates separated by zonal centrifugation showed three peaks od cytochrome oxidase activity which shifted to the heavier end of the gradient after PMSG treatment. These studies suggest that PMSG treatment influences ovarian mitochondria, possibly by stimulating the synthesis of additional functional components and/or the biogenesis of new mitochondria. Aminoglutethimide addition to bovine luteal mitochondria decreased steroidogenesis by 60% when succinate was used as substrate. However, there was a 16% increase in the ADP:O ratio, apparently due to a decrease in oxygen utilization. When oligomycin was added to luteal mitochondria, there was a 30% decrease in the ACP:O ratio but a 300% increase in [4-14C]cholesterol conversion. Dinitrophenol also decreased mitochondrial steroidogenesis. These results suggest that energy obtained from succinate oxidation can be diverted from phosphorylation to support steroidogenesis.

UI MeSH Term Description Entries
D008184 Luteal Cells PROGESTERONE-producing cells in the CORPUS LUTEUM. The large luteal cells derive from the GRANULOSA CELLS. The small luteal cells derive from the THECA CELLS. Lutein Cells,Granulosa-Luteal Cells,Granulosa-Lutein Cells,Large Luteal Cells,Small Luteal Cells,Theca-Luteal cells,Theca-Lutein Cells,Cell, Granulosa-Luteal,Cell, Granulosa-Lutein,Cell, Large Luteal,Cell, Luteal,Cell, Lutein,Cell, Small Luteal,Cell, Theca-Lutein,Cells, Granulosa-Luteal,Cells, Granulosa-Lutein,Cells, Large Luteal,Cells, Luteal,Cells, Lutein,Cells, Small Luteal,Cells, Theca-Lutein,Granulosa Luteal Cells,Granulosa Lutein Cells,Granulosa-Luteal Cell,Granulosa-Lutein Cell,Large Luteal Cell,Luteal Cell,Luteal Cell, Large,Luteal Cell, Small,Luteal Cells, Large,Luteal Cells, Small,Lutein Cell,Small Luteal Cell,Theca Luteal cells,Theca Lutein Cells,Theca-Luteal cell,Theca-Lutein Cell,cell, Theca-Luteal,cells, Theca-Luteal
D008854 Microscopy, Electron Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen. Electron Microscopy
D008928 Mitochondria Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed) Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D010053 Ovary The reproductive organ (GONADS) in female animals. In vertebrates, the ovary contains two functional parts: the OVARIAN FOLLICLE for the production of female germ cells (OOGENESIS); and the endocrine cells (GRANULOSA CELLS; THECA CELLS; and LUTEAL CELLS) for the production of ESTROGENS and PROGESTERONE. Ovaries
D010085 Oxidative Phosphorylation Electron transfer through the cytochrome system liberating free energy which is transformed into high-energy phosphate bonds. Phosphorylation, Oxidative,Oxidative Phosphorylations,Phosphorylations, Oxidative
D011284 Pregnenolone A 21-carbon steroid, derived from CHOLESTEROL and found in steroid hormone-producing tissues. Pregnenolone is the precursor to GONADAL STEROID HORMONES and the adrenal CORTICOSTEROIDS. 5-Pregnen-3-beta-ol-20-one,5 Pregnen 3 beta ol 20 one
D011374 Progesterone The major progestational steroid that is secreted primarily by the CORPUS LUTEUM and the PLACENTA. Progesterone acts on the UTERUS, the MAMMARY GLANDS and the BRAIN. It is required in EMBRYO IMPLANTATION; PREGNANCY maintenance, and the development of mammary tissue for MILK production. Progesterone, converted from PREGNENOLONE, also serves as an intermediate in the biosynthesis of GONADAL STEROID HORMONES and adrenal CORTICOSTEROIDS. Pregnenedione,Progesterone, (13 alpha,17 alpha)-(+-)-Isomer,Progesterone, (17 alpha)-Isomer,Progesterone, (9 beta,10 alpha)-Isomer
D002458 Cell Fractionation Techniques to partition various components of the cell into SUBCELLULAR FRACTIONS. Cell Fractionations,Fractionation, Cell,Fractionations, Cell
D002784 Cholesterol The principal sterol of all higher animals, distributed in body tissues, especially the brain and spinal cord, and in animal fats and oils. Epicholesterol
D003576 Electron Transport Complex IV A multisubunit enzyme complex containing CYTOCHROME A GROUP; CYTOCHROME A3; two copper atoms; and 13 different protein subunits. It is the terminal oxidase complex of the RESPIRATORY CHAIN and collects electrons that are transferred from the reduced CYTOCHROME C GROUP and donates them to molecular OXYGEN, which is then reduced to water. The redox reaction is simultaneously coupled to the transport of PROTONS across the inner mitochondrial membrane. Cytochrome Oxidase,Cytochrome aa3,Cytochrome-c Oxidase,Cytochrome Oxidase Subunit III,Cytochrome a,a3,Cytochrome c Oxidase Subunit VIa,Cytochrome-c Oxidase (Complex IV),Cytochrome-c Oxidase Subunit III,Cytochrome-c Oxidase Subunit IV,Ferrocytochrome c Oxygen Oxidoreductase,Heme aa3 Cytochrome Oxidase,Pre-CTOX p25,Signal Peptide p25-Subunit IV Cytochrome Oxidase,Subunit III, Cytochrome Oxidase,p25 Presequence Peptide-Cytochrome Oxidase,Cytochrome c Oxidase,Cytochrome c Oxidase Subunit III,Cytochrome c Oxidase Subunit IV,Oxidase, Cytochrome,Oxidase, Cytochrome-c,Signal Peptide p25 Subunit IV Cytochrome Oxidase,p25 Presequence Peptide Cytochrome Oxidase

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