Bax参与KATP通道对神经元损伤的保护作用

Bax is involved in KATP-mediated protection of the hippocampal neurons against hypoxic exposure

目的探讨ATP敏感性钾通道(KATP)介导对缺氧海马神经元损伤保护作用的分子机制。方法原代培养7d后,对神经元进行缺氧(5%CO2和95%N2),同时分别给予神经元KATP通道的阻断剂甲糖宁(100μmol/L)和KATP通道的激动剂二氮嗪(100μmol/L),MTT法检测细胞活性,RT-PCR检测Bax的mRNA表达水平。结果单纯缺氧组,缺氧+二氮嗪组和缺氧+甲糖宁组的细胞存活率分别是(75.7±2.8)%(n=7)、(55.7±2.5)%(n=6)和(81.1±2.4)%(n=6),各加药组与单纯缺氧组比较有显著性差异(P<0.01)。缺氧+二氮嗪组中Bax的mRNA表达水平与单纯缺氧组相比明显下降(n=5)(P<0.01),在缺氧+甲糖宁组中Bax的mRNA表达水平相对于单纯缺氧组高表达(n=5)(P<0.05);而在常氧时各用药组中细胞存活率以及Bax的mRNA表达水平与对照组相比都均无显著性差异。结论Bax参与KATP通道对神经元损伤的保护作用。

Objective To investigate the mechanism of KATP-mediated protection of the hippocampal neurons exposed to hypoxia. Methods The neurons were exposed to hypoxia （0% O2, 5% CO2 and 95% N2） or treated with tolbutamide or diazoxide for 12 or 24 h 1 week after seeding. MTT assay was used to measure the cell viability. RT-PCR was performed to detect Bax mRNA expression. Results MTT assay showed a much lower survival rate （75.7±2.8%） of the neurons exposed to severe hypoxia （PO2=0 mmHg） than that of the neurons in normoxia （P〈0.01, n=7）. Tolbutamide （100 μmol/L） treatment significantly reduced the survival rate of the neurons to （55.7±2.5）%, while diazoxide （100 μmol/L） increased the survival rate to （81.1±2.4）% （P〈0.01, n=6）. In normoxia, neither diazoxide nor tolbutamide significantly affected the cell viability （P〉0.05, n=6）. A significant increase in Bax （P〈0.01） and Fas （P〈0.01） mRNA expression occurred in the neurons exposed to severe hypoxia （PO2=0 mmHg） as compared with the expressions in cells in normoxia （PO2=144 mmHg）. In the hypoxic neurons, tolbutamide significantly increased Bax mRNA expression（P〈0.05）, while diazoxide reduced the expression to a level comparable with that observed in normoxic condition. Conclusion Bax is involved in KATP-mediated protection of hippocampal neurons exposed to hypoxia.