雌激素对H_2O_2诱导的氧化应激的保护作用及机制

为了探讨雌激素17β-estradiol对H2O2诱导的氧化应激的影响及其可能机制。本研究将H2O2作用于大鼠皮层神经元,利用四甲基偶氮唑盐(MTT)检测单独H2O2或者17β-estradiol存在时其对细胞活力和乳酸脱氢酶(LDH)释放的影响;检测单独H2O2或者17β-estradiol存在时其对糖原合成激酶-3β(GSK-3β)活性的影响及其对磷酸化和非磷酸化GSK-3β表达的影响;检测GSK-3β抑制剂LiCl对H2O2诱导的细胞活力的影响;检测雌激素受体抑制剂ICI-182780存在时17β-estradiol对GSK-3β表达的影响。结果显示:(1)H2O2作用于大鼠皮层神经元后显著降低细胞的活力,各种浓度的17β-estradiol预处理细胞后均能部分阻断H2O2对细胞活力的影响;(2)H2O2作用后显著增加细胞乳酸脱氢酶的释放,而17β-estradiol则部分拮抗此种作用;(3)H2O2增加了GSK-3β的活性,而提前加入17β-estradiol则可以降低H2O2诱导的GSK-3β活性增加;(4)H2O2降低了GSK-3β的磷酸化,而17β-estradiol则部分拮抗了这种作用;(5)GSK-3β抑制剂LiCl也可以拮抗H2O2诱导的细胞活力下降;(6)与对照组相比,17β-estradiol本身亦可增加GSK-3β的磷酸化,此作用可被雌激素受体抑制剂ICI-182780部分拮抗,而ICI-182780本身对GSK-3β的磷酸化无显著影响。以上结果提示,17β-estradiol可以拮抗H2O2诱导的氧化应激作用,17β-estradiol通过与其受体结合而抑制GSK-3β的活性可能是其发挥保护作用的机制之一。

Neuroprotective effect and mechanism of estrogen on H2O2-induced oxidative stress

To investigate the neuroprotective effect and mechanism of 17β-estradiol on H2O2-induced oxidative stress. H2O2 was added to the neurons of rat primary cortex and its effects on cell viability and lactate dehydrogenase (LDH) release into the cell media were detected with and without the presence of 17β-estradiol. The effects of H2O2 on GSK-3β activity and the expression of phosphorylated and nonphosphorylated GSK-3β were measured with and without the presence of 17β-estradiol. The effect of GSK-3β inhibitor-LiCI on cell viability and the effect of estrogen receptor specific inhibitor ICI-182780 on 17β-estradiol induced GSK-3β phosphorylation were also analyzed. The results showed that: (1) H2O2 decreased cell viability prominently in rat cortical neurons and this effect could be partially blocked by pretreatment of cells with serial concentrations of 17β-estradiol; (2) H2O2 increased the secretion of LDH into the cell media, which was alleviated by 17β-estradiol preincubation; (3) H2O2 increased GSK-3β activity and this effect could be partially blocked by preincubation of cells with 17β-estradiol; (4) H2O2 decreased GSK-3β phosphorylation and the effect could be antagonized by 17β-estradiol; (5) GSK-3β inhibitor-LiCI could also protect rat cortical neurons from H2O2-incuded oxidative stress in cell viability; (6) 17β-estradiol itself could also increase GSK-3β phosphorylation as compared with control group, and this effect could be partially reversed by estrogen receptor antagonist ICI-182780, but the latter alone had no effect on GSK-3β phosphorylation. These results suggest that 17β-estradiol could partially alleviate H2O2-induced oxidative stress. GSK-3β deactivation may underlie 17β-estradiol's neuroprotective effect on cell viability, and this effect may be partially mediated through estrogen receptor dependent mechanism.