重度缺氧中海马神经元KATP通道的表达改变

Alteration of ATP-sensitive K^＋ channel expression in hippocampal neurons after severe chronic hypoxia

目的探讨重度缺氧状态中ATP敏感性钾通道（KATP）通道在海马神经元上的表达变化。方法取培养1周的新生大鼠海马神经元分为4组：第1组为正常对照组．在正常氧状态中（5％CO2、95％空气）孵育8h；第2组为处理组，在模拟的缺氧状态（5％CO2、95％N2）孵育8h（单纯缺氧组）；第3组为二氮嗪＋缺氧组，在缺氧处理的同时添加KATP通道激动剂二氮嗪（100μmol／L），处理时间为8h；第4组为甲糖宁＋缺氧组，在缺氧处理的同时添加KATP通道阻断剂甲糖宁（100μmol／L），处理时间为8h。利用MTT、免疫印迹及RT—PCR技术，比较4组细胞存活情况以及缺氧状态中神经元上KATP通道的表达改变。结果缺氧8h后，二氮嗪能明显降低细胞的凋亡数量，甲糖宁使细胞的凋亡数量增加，与正常对照组比较，差异均有统计学意义（氏0．05）。缺氧状态中KATP通道的SUR1亚基的表达明显增加，而Kir6．2亚基表达量则无明显改变，与正常对照组比较，差异均有统计学意义（氏0．05）。结论KATP通道的活性及表达改变，对缺氧中的海马神经元的保护起到重要作用。

Objective To explore the alteration of ATP-sensitive K^＋ （KATP） channel expression in hippocampal neurons after severe chronic hypoxia. Methods The hippocampal neurons from 1-week-old rat were incubated and divided into normal control （incubated under 5% CO2 and 95% air for 8 h）, hypoxia （incubated under 5% CO2 and 95% N2 for 8 h）, hypoxia combined with diazoxide-treated （incubated with 100 μmol/L diazoxide under 5% CO2 and 95% N2 for 8 h） and hypoxia combined with tolbutamide-treated groups （incubated with 100 μmol/L tolbutamide under 5% CO2 and 95% N2 for 8 h）. Cell apoptosis was identified by MTT. And the mRNA and protein expressions of KATP channel were estimated by RT-PCR and Western blot analysis, respectively. Results Hypoxia combined with diazoxide-treated group showed a significantly decreased apoptosis rate of neuron as compare with the normal control group 8 h after hypoxia （P〈0.05）; while hypoxia combined with tolbutamide-treated group showed a significantly increased apoptosis rate of neuron compared with the normal control group （P〈 0.05）. The expression of SUR1 in the three hypoxia groups significantly increased as compared with that in the normal control group （P〈0.05）; however, the expression of Kir6.2 in the three hypoxia groups did not change as compared with that in the normal control group （P〉0.05）. Conclusion Kaa~ channels can protect the hippocampal neurons under severe chronic hypoxia through the activation of KATP channels and upregulation of expression of KATP channels SUR1 subunit.