Protective effect of 17β-estradiol on hydrogen peroxide induced apoptosis of rat nucleus pulposus cells

Background: It has been suggested that intervertebral disc (IVD) cell apoptosis playing a key role in promoting disc degeneration, and Oxidative stress has been proved to induce apoptosis of nucleus pulposus cells (NPCs) in contributing to the process of IVD degeneration. 17 beta-Estradiol (17 beta-E-2) has been reported for its protective effect on NPCs in our previous studies. However, it is not yet clear whether 17 beta-E-2 has the protective effect on NPCs against apoptosis induced by oxidative stress. Purpose: Based on apoptotic cell model induced by Hydrogen Peroxide (H2O2), the current research was design to explore the effect of 17 beta-E-2 on rat NPCs against apoptosis. Methods: NPCs were isolated from male Sprague-Dawley rats and cultured in complete medium. After two weeks, the NPCs were treated with H2O2 (1, 10, 100, 500 and 1000 mu M/L, respectively) for 6 h, and 500 mu M/L H2O2 for (1, 3, 6, 12 and 24 h, respectively). Cell counting kit-8 assay was performed to determine cell viability. LDH assay was performed to assess cytotoxicity after different treatments. Apoptotic incidence was analyzed by Fluorescence Activating Cell Sorter (FACS), morphological changes, as well as western blot of active caspase-3. Results: The results showed that H2O2 induced notable apoptosis and over expression of active caspase-3 in a dose-and time-dependent manner. However, the adverse effect caused by H2O2 was obviously reversed by 17 beta-E-2. Besides, cell viability was decreased after treatment with H2O2, which was then increased by the addition of 17 beta-E-2. In particular, the dose-dependent effect of 17 beta-E-2 was remarkable. During the experiments, it was found that all effects resulting from 17 beta-E-2 were eliminated by estrogen receptor antagonist ICI182, 780. Conclusions: These results obtained in this study suggest that 17 beta-E-2 can effectively protect rat NPCs from peroxide-induced apoptosis in a dose-dependent manner, implying the potential of 17 beta-E-2 to prevent IVDD onset or slow its progression in the early stage.