Mitochondrial inhibition prior to oxygen-withdrawal facilitates the occurrence of hypoxia-induced spreading depression in rat hippocampal slices
Mitochondrial inhibition prior to oxygen-withdrawal facilitates the occurrence of hypoxia-induced spreading depression in rat hippocampal slices
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DOI：
10.1152/jn.01015.2005
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发表时间：
2006-07-01
影响因子：
2.5
通讯作者：
Mueller, Michael
中科院分区：
文献类型：
--
作者：
Gerich, Florian J.;Hepp, Sebastian;Mueller, Michael
缺氧阻断线粒体呼吸。在大鼠海马脑片中，这触发了CA 1神经元的大量去极化和细胞外DC电位的负移，这是缺氧诱导的扩散性抑制（HSD）的特征性标志。为了揭示线粒体对缺氧感测和HSD点燃的贡献，我们修改了线粒体功能。线粒体解偶联羰基氰4-（三氟甲氧基）苯腙（FCCP，1 μ M）缺氧前加速发病，缩短HSD的持续时间。寡霉素（10 μ g/ml）阻断线粒体ATP合成没有效果。鱼藤酮（20 μ M），diphenyleneiodonium（25 μ M），或抗霉素A（20 μ M）的线粒体呼吸抑制也加速HSD发病和缩短HSD持续时间。3-硝基丙酸（1 mM）增加HSD持续时间。氰化物（100 μ M）加速HSD发作和增加HSD持续时间。在较高浓度下，氰化物（1 mM），叠氮化物（2 mM），FCCP（10 μ M）触发SD发作自己。与对照HSD相比，氰化物和叠氮化物诱导的SD的固有光信号的空间范围更明显。监测NADH（烟酰胺腺嘌呤二核苷酸）和FAD（黄素腺嘌呤二核苷酸）自发荧光和线粒体膜电位证实了所用药物的线粒体靶向作用。除了1 mM氰化物，没有治疗严重降低细胞ATP水平，ATP，NADH，或FAD水平和HSD发作的时间之间没有相关性。因此，ATP消耗或由于NADH/FADH（2）积累而引起的胞质还原转变不能作为HSD加速线粒体抑制作用发生的一般解释。额外的氧化还原对（谷胱甘肽）或事件下游的线粒体去极化需要考虑。
Oxygen withdrawal blocks mitochondrial respiration. In rat hippocampal slices, this triggers a massive depolarization of CA1 neurons and a negative shift of the extracellular DC potential, the characteristic sign of hypoxia-induced spreading depression (HSD). To unveil the contribution of mitochondria to the sensing of hypoxia and the ignition of HSD, we modified mitochondrial function. Mitochondrial uncoupling by carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone ( FCCP, 1 mu M) prior to hypoxia hastened the onset and shortened the duration of HSD. Blocking mitochondrial ATP synthesis by oligomycin ( 10 mu g/ml) was without effect. Inhibition of mitochondrial respiration by rotenone (20 mu M), diphenyleneiodonium (25 mu M), or antimycin A (20 mu M) also hastened HSD onset and shortened HSD duration. 3-nitropropionic acid (1 mM) increased HSD duration. Cyanide ( 100 mu M) hastened HSD onset and increased HSD duration. At higher concentrations, cyanide (1 mM), azide (2 mM), and FCCP (10 mu M) triggered SD episodes on their own. Compared with control HSD, the spatial extent of the intrinsic optical signals of cyanide- and azide-induced SDs was more pronounced. Monitoring NADH ( nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) autofluorescence and mitochondrial membrane potential verified the mitochondrial targeting by the drugs used. Except 1 mM cyanide, no treatment reduced cellular ATP levels severely and no correlation was found between ATP, NADH, or FAD levels and the time to HSD onset. Therefore ATP depletion or a cytosolic reducing shift due to NADH/FADH(2) accumulation cannot serve as a general explanation for the hastening of HSD onset on mitochondrial inhibition. Additional redox couples (glutathione) or events downstream of the mitochondrial depolarization need to be considered.