Estradiol rapidly inhibits soluble guanylyl cyclase expression in rat uterus

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The National Academy of Sciences

RESUMO

Previous reports that investigated the regulation of the NO/soluble guanylyl cyclase (sGC)/cGMP pathway by estrogenic compounds have focused primarily on the levels of NO, NO-producing enzymes, and cGMP in various tissues. In this study, we demonstrate that 17β-estradiol (E2) regulates the α1 and β1 subunits of the NO receptor, sGC, at the mRNA and protein levels in rat uterus. Using real-time quantitative PCR, we found that within 1 h of in vivo E2 administration to rats, sGC mRNA levels begin to diminish. After 3 h, there is a maximal diminution of sGC mRNA expression (sGC α1 10% and sGC β1 33% of untreated). This effect was blocked by the estrogen receptor antagonist, ICI 182,780, indicating that estrogen receptor is required. The effect of E2 also was observed in vitro with incubations of uterine tissue, indicating that the response does not depend on the secondary release of other hormones or factors from other tissues. Puromycin did not block the effect, suggesting the effects occur because of preexisting factors in uterine tissues and do not require new protein synthesis. Using immunoblot analysis, we found that sGC protein levels also were reduced by E2 over a similar time course as the sGC mRNA. We conclude that sGC plays a vital role in the NO/sGC/cGMP regulatory pathway during conditions of elevated estrogen levels in the rat uterus as a result of the reduction of sGC expression.

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