title: Additive effects of low concentrations of estradiol-17β and progesterone on nitric oxide production by human vascular endothelial cells through shared signaling pathways.
abstract: Potential cardiovascular benefits of low-dose formulations of estrogens and progesterone (P4) for treating climacteric symptoms in postmenopausal women remain unclear because information is lacking on their combined vascular effects. Protective effects of low concentrations (5nM) of P4 and estradiol-17β (E2), alone and in combination (P4+E2), were investigated in a nongenomic model of vascular protection which measured acute increases in nitric oxide (NO) production by cultured human umbilical vein endothelial cells (HUVECs). Treatment with 5nM P4+E2 for twenty minutes significantly increased NO production and endothelial NO synthase (eNOS) phosphorylation, whereas 5nM treatments with either steroid alone were ineffective. The 5nM P4+E2 treatment also increased phosphorylation of ERK and Akt, mimicking the effects of higher concentrations of P4 and E2 alone. Pre-treatment with inhibitors of PI3K (wortmannin), Akt (ML-9), and MAP kinase (AZD6244 and U0126) completely blocked the NO response to 5nM P4+E2. Combined 5nM treatments with specific estrogen and progesterone receptor agonists showed an involvement of membrane progesterone receptor alpha (mPRα, also known as PAQR7), G protein-coupled estrogen receptor 1 (GPER), and estrogen receptor alpha (ERα), but not ERβ, in P4+E2 stimulation of NO production. P4+E2 also exerted genomic actions, increasing mPRα, GPER, cyclooxygenase-1, and prostacyclin-synthase mRNA levels. Taken together, the results show that a low concentration of P4+E2 rapidly increases NO production in HUVECs through mPRα, ERα, and GPER and involves common signaling pathways, PI3K/Akt and MAP kinase. These in vitro findings suggest that low doses of E2 and P4 may also have some beneficial cardiovascular effects in vivo when administered as hormone replacement therapy (HRT) for post-menopausal women.
authors.affiliation: Marine Science Institute, University of Texas at Austin, 750 Channel View Drive, Port Aransas, TX 78373, United States. Electronic address: yfpang@utexas.edu.
authors.forename: Yefei
authors.initials: Y
authors.lastname: Pang
authors.affiliation: Marine Science Institute, University of Texas at Austin, 750 Channel View Drive, Port Aransas, TX 78373, United States. Electronic address: peter.thomas@utexas.edu.
authors.forename: Peter
authors.initials: P
authors.lastname: Thomas
mesh_terms: D002478:Cells, Cultured; D051545:Cyclooxygenase 1 / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000378:metabolism; D020249:Hormone Replacement Therapy; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D020935:MAP Kinase Signaling System; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D015398:Signal Transduction; D014470:Umbilical Cord / Q000378:metabolism
chemical_list: C506487:ESR1 protein, human; D047628:Estrogen Receptor alpha; C109584:GPER1 protein, human; D012333:RNA, Messenger; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D011980:Receptors, Progesterone; D009569:Nitric Oxide; D011374:Progesterone; D004958:Estradiol; D003577:Cytochrome P-450 Enzyme System; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051545:Cyclooxygenase 1; C496511:PTGS1 protein, human; C472456:PTGIS protein, human
keywords: Additive; Estradiol-17β; HUVECs; Nitric oxide; Progesterone; Signaling pathways