Dual action of H2O2 on placental hCG secretion:: Implications for oxidative stress in preeclampsia

Objective: Our previously published findings showed that circulating levels of H2O2 were increased and correlated with high levels of hCG in women with preeclampsia, suggesting that oxidative stress modulates placental hormone synthesis. The aim of this study was to investigate in vitro the effects of H2O2 on placental secretion of hCG. Design and methods: In vitro trophoblasts were stimulated with increasing concentrations of H2O2 and the de novo hCG secretion was assayed. Results: Stimulation with low concentrations of H2O2 (1-50 mu M) enhances cytotrophoblastic hCG secretion, whereas concentrations of H2O2 > 50 mu M reduce hCG secretion in a dose-dependent manner. Conclusions: Our findings emphasize that: (1) H2O2 may have dual action on placental activity and acts not only as a cytotoxic mediator, but also as a signaling molecule able to induce hCG secretion; (2) hCG may be a protective antioxidant released by the placenta to counter low oxidative stress challenge. (c) 2006 The Canadian Society of Clinical Chemists. All rights reserved.