title: 17beta-estradiol activates ICI 182,780-sensitive estrogen receptors and cyclic GMP-dependent thioredoxin expression for neuroprotection.
abstract: Clinical studies suggest that estrogen may improve cognition in Alzheimer's patients. Basic experiments demonstrate that 17beta-estradiol protects against neurodegeneration in both cell and animal models. In the present study, a human SH-SY5Y cell model was used to investigate molecular mechanisms underlying the receptor-mediated neuroprotection of physiological concentrations of 17beta-estradiol. 17beta-estradiol (<10 nM) concomitantly increased neuronal nitric oxide synthase (NOS1) expression and cell viability. 17beta-estradiol-induced neuroprotection was blocked by the receptor antagonist ICI 182,780, also prevented by inhibitors of NOS1 (7-nitroindazole), guanylyl cyclase (LY 83,583), and cGMP-dependent protein kinase (PKG) (Rp-8-pCPT-cGMPs). In addition to the expression of NOS1 and MnSOD, 17beta-estradiol increased the expression of the redox protein thioredoxin (Trx), which was blocked by the inhibition of either cGMP formation or PKG activity. The expression of heme oxygenase 2 and brain-derived neurotrophic factor was not altered. Estrogen receptor-enhanced cell viability against oxidative stress may be linked to Trx expression because the Trx reductase inhibitor, 5,5'-dithio-bis(2-nitrobenzoic acid) significantly reduced the cytoprotective effect of 17beta-estradiol. Furthermore, Trx (1 microM) inhibited lipid peroxidation, proapoptotic caspase-3, and cell death during oxidative stress caused by serum deprivation. We conclude that cGMP-dependent expression of Trx--the redox protein with potent antioxidative and antiapoptotic properties--may play a pivotal role in estrogen-induced neuroprotection.
authors.affiliation: Department of Neuroscience and Anatomy, Penn State University College of Medicine, M.S. Hershey Medical Center, Hershey, Pennsylvania, USA.
authors.forename: Sang Y
authors.initials: SY
authors.lastname: Lee
authors.forename: Tsugunobu
authors.initials: T
authors.lastname: Andoh
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Murphy
authors.forename: Chuang C
authors.initials: CC
authors.lastname: Chiueh
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D006152:Cyclic GMP / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D000077267:Fulvestrant; D006801:Humans; D008954:Models, Biological; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D018384:Oxidative Stress / Q000187:drug effects; D011960:Receptors, Estrogen / Q000037:antagonists & inhibitors* / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D013482:Superoxide Dismutase / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects / Q000378:metabolism
chemical_list: D004965:Estrogen Antagonists; D018696:Neuroprotective Agents; D011960:Receptors, Estrogen; D000077267:Fulvestrant; D009569:Nitric Oxide; D004958:Estradiol; D013879:Thioredoxins; C496320:NOS1 protein, human; C496314:NOS3 protein, human; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP