Abstract
Rapid uterine vasodilatation after estrogen administration is believed to be mediated by endothelial production of nitric oxide (NO) via endothelial NO synthase (eNOS). However, the mechanism(s) by which estrogen activates eNOS in uterine artery endothelial cells (UAEC) is unknown. In this study, we observed that estradiol-17beta (E2) and E2-BSA rapidly (<2 min) increased total NOx production in UAEC in vitro. This was associated with rapid eNOS phosphorylation and activation but was unaltered by pretreatment with actinomycin-D. Estrogen receptor-alpha protein was detectable in isolated plasma membrane proteins by immunoblotting, and E2-BSA-fluorescein isothiocyanate binding was evident on the plasma membrane of UAEC. E2 did not mobilize intracellular Ca2+, but E2 and ionomycin in combination induced greater eNOS phosphorylation than either E2 or ionomycin alone. E2 did not stimulate rapid Akt phosphorylation. E2 stimulated rapid ERK2/1 activation in a time- and dose-dependent manner, with maximal responses observed at 5-10 min with E2 (10 nm to 1 microm) treatment. Acute activation of eNOS and NOx production by E2 could be inhibited by PD98059 but not by LY294002. When E2-BSA was applied, similar responses in NOx production, eNOS, and ERK2/1 activation to those of E2 were achieved. In addition, E2 and E2-BSA-induced ERK2/1 activation and ICI 182,780 could inhibit NOx production by E2. Thus, acute activation of eNOS to produce NO in UAEC by estrogen is at least partially through an ERK pathway, possibly via estrogen receptor localized on the plasma membrane. This pathway may provide a novel mechanism for NO-mediated rapid uterine vasodilatation by estrogen.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Arteries / physiology
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Calcium / metabolism
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Cell Membrane / metabolism
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Endothelium, Vascular / enzymology
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Enzyme Activation / drug effects
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Estradiol / analogs & derivatives*
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Estradiol / pharmacology*
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Estrogen Antagonists / pharmacology
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Estrogen Receptor alpha
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Female
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Fulvestrant
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Insulin-Like Growth Factor I / pharmacology
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MAP Kinase Kinase 1
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MAP Kinase Signaling System / drug effects
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MAP Kinase Signaling System / physiology*
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Mitogen-Activated Protein Kinase 1 / metabolism*
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinase Kinases / metabolism
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Mitogen-Activated Protein Kinases / metabolism
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Nitric Oxide / metabolism
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Nitric Oxide Synthase / metabolism*
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Nitric Oxide Synthase Type III
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Phosphorylation / drug effects
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Pregnancy
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-akt
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Proto-Oncogene Proteins c-raf / metabolism
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Receptors, Estrogen / metabolism*
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Serum Albumin, Bovine / pharmacology
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Sheep
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Uterus / blood supply*
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Uterus / physiology
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Vasodilation / drug effects
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Vasodilation / physiology
Substances
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Estrogen Antagonists
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Estrogen Receptor alpha
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Proto-Oncogene Proteins
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Receptors, Estrogen
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Fulvestrant
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Serum Albumin, Bovine
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Nitric Oxide
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Estradiol
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Insulin-Like Growth Factor I
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Nitric Oxide Synthase
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Nitric Oxide Synthase Type III
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Protein Serine-Threonine Kinases
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Proto-Oncogene Proteins c-akt
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Proto-Oncogene Proteins c-raf
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Mitogen-Activated Protein Kinase 1
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Mitogen-Activated Protein Kinase 3
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Mitogen-Activated Protein Kinases
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MAP Kinase Kinase 1
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Mitogen-Activated Protein Kinase Kinases
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Calcium