Nrf2-Mediated Resistance to Oxidant-Induced Redox Disruption in Embryos

Events that control developmental changes occur during specific windows of gestation and if disrupted, can lead to dysmorphogenesis or embryolethality. One largely understudied aspect of developmental control is redox regulation, where the untimely disruption of intracellular redox potentials (Eh) may alter development, suggesting that tight control of developmental-stagespecific redox states is necessary to support normal development. In this study, mouse gestational day 8.5 embryos in whole embryo culture were treated with 10 mu M dithiole-3-thione (D3T), an inducer of nuclear factor (erythroid-derived 2)-like 2 (Nrf2). After 14 hr, D3T-treated and -untreated conceptuses were challenged with 200 mu M hydrogen peroxide (H2O2) to induce oxidant-induced change to intracellular Ehs. Redox potentials of glutathione (GSH), thioredoxin-1 (Trx1), and mitochondrial thioredoxin-2 (Trx2) were then measured over a 2-hr rebounding period following H2O2 treatment. D3T treatment increased embryonic expression of known Nrf2-regulated genes, including those responsible for redox regulation of major intracellular redox couples. Exposure to H2O2 without prior D3T treatment produced significant oxidation of GSH, Trx1, and Trx2, based on Eh values, where GSH and Trx2 Eh recovered, reaching to pre-H2O2 Eh ranges, but Trx1 Eh remained oxidized. Following H2O2 addition in culture to embryos that received D3T pretreatments, GSH, Trx1, and Trx2 were insulated from significant oxidation. These data show that Nrf2 activation may serve as a means to protect the embryo from chemically induced oxidative stress through the preservation of intracellular redox states during development, allowing normal morphogenesis to ensue. Birth Defects Res (Part B) 95:195-201, 2012. (C) 2012 Wiley Periodicals, Inc.