Effect of Incubation with NADPH Generator on Progesterone Bound to Nuclei of the Rat Uterus

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概要

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• The metabolism of progesterone bound to uterine nuclear progesterone receptors was accelerated <I>in vitro</I> by incubation at 25°C for 30min with NADPH generator. The characteristics of progesterone metabolites and receptors were examined by <SUP>3</SUP>H-R5020 exchange assay. Progesterone bound nuclei were prepared from uteri of estradiol-primed progesteronetreated ovariectomized rats. The specific nuclear R5020 binding sites examined by exchange assay were identified as specific progesterone receptors by the binding specificity of R5020 to progesterone receptors, their high affinity for progesterone, and the increase in the number of specific binding sites in response to a progesterone injection.<BR>Major metabolites of progesterone specifically bound to nuclear receptors by incubation with the cofactor were 5α-dihydroprogesterone (5α-DHP) and 3α-hydroxy-5α-pregnan-20-one. The relative binding affinity of the progesterone receptor for 5α-DHP at 0°C was 27.5% of progesterone, but 3α-hydroxy-5α-pregnan-20-one had no binding affinity for the receptor. Incubation of the nuclei in the presence of NADPH generator decreased the number of R5020 binding sites from 143 fmol to 25 fmol per 100μg DNA, and increased the dissociation constant of the receptor with progesterone from 2.56nM to 7.78nM.<BR>Results suggest that after gene activation, the specific binding sites of progesterone to nuclear receptors may be denatured in the presence of NADPH, causing both progesterone and receptors to dissociate from the receptors and chromatins, respectively, and that the dissociated progesterone may be converted to 5α-reduced pregnanes which have lower affinity for the receptor.

• 社団法人 日本内分泌学会の論文

著者

• ICHIKAWA SHIGETAKA

  Laboratory of Animal Reproduction, College of Agriculture, University of Osaka Prefecture

• MORIOKA HIROSHI

  Laboratory of Animal Reproduction, college of Agriculture, University of Osaka Prefecture

• KONISHI KAZUYUKI

  Laboratory of Animal Reproduction, college of Agriculture, University of Osaka Prefecture

関連論文

• The Effect of Estrogen on Fetal Survival in Progesterone-Treated Ovariectomized Rats
• The Effect of Ovarian Hormones on Stress Relaxation in the Uterus of the Pregnant Rat
• Effect of Incubation with NADPH Generator on Progesterone Bound to Nuclei of the Rat Uterus
• Effect of the Placenta on the Growth and Function of Artificially Formed Secondary Corpora Lutea of Pregnancy in Rats

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