Mitochondrial calcium ion and membrane potential transients follow the pattern of epileptiform discharges in hippocampal slice cultures
Mitochondrial calcium ion and membrane potential transients follow the pattern of epileptiform discharges in hippocampal slice cultures
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DOI：
10.1523/jneurosci.4000-04.2005
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发表时间：
2005-04-27
影响因子：
5.3
通讯作者：
Kann, O
中科院分区：
文献类型：
--
作者：
Kovács, R;Kardos, J;Kann, O
新出现的证据表明，线粒体功能障碍有助于癫痫的病理生理学。癫痫发作时反复出现的线粒体Ca ~（2+）负荷可能对线粒体膜电位（Δ Psim）和质子动力产生影响。通过电生理学和共聚焦激光扫描显微镜，我们研究了海马脑片培养中低镁离子灌注诱导的癫痫样活动的影响，对Delta Psi m和线粒体Ca 2+离子浓度变化的影响线粒体区室通过使用线粒体-钙离子通道（[Ca 2 +]（m））监测斑片状CA 3锥体细胞的索马体和树突中的Δ Psi m来鉴定。特定电压敏感染料罗丹明-123（Rh-123）。发作间期活动伴随着局限于小树突中少数线粒体的局部线粒体去极化。与此相反，鲁棒Rh-123释放到胞质溶胶中观察到在类线粒体事件（SLE），表明线粒体的同时去极化。这主要依赖于Ca ~（2+）离子的摄取和排出，因为Ru 360抑制线粒体Ca ~（2+）离子单向转运体，7-氯-5-甲基苯甲酸酯抑制线粒体Na ~+/Ca ~（2+）离子交换体。（2-氯苯基）-1，5-二氢-4，1-苯并硫氮杂卓-2（3 H）-酮，但不是线粒体通透性转换孔的抑制剂，环孢菌素A，同时线粒体去极化的Ca ~（2+）依赖性表明癫痫样活动期间线粒体膜Ca ~（2+）循环增强。事实上，[Ca 2 +]（m）波动在发作间期活动在单个树突，这些波动蔓延到整个线粒体室在SLE，显示使用特定的染料（rhod-2和rhod-ff）和空间频率为基础的图像分析。这些发现加强了这样的假设，即癫痫活动导致线粒体功能的Ca 2+依赖性变化，这可能有助于癫痫期间的神经元损伤。
Emerging evidence suggests that mitochondrial dysfunction contributes to the pathophysiology of epilepsy. Recurrent mitochondrial Ca2+ ion load during seizures might act on mitochondrial membrane potential (Delta Psi m) and proton motive force. By using electrophysiology and confocal laser-scanning microscopy, we investigated the effects of epileptiform activity, as induced by low-Mg2+ ion perfusion in hippocampal slice cultures, on changes in Delta Psi m and in mitochondrial Ca2+ ion concentration ([Ca2+](m)).The mitochondrial compartment was identified by monitoring Delta Psi m in the soma and dendrites of patched CA3 pyramidal cells using the mitochondria-specific voltage-sensitive dye rhodamine-123 (Rh-123). Interictal activity was accompanied by localized mitochondrial depolarization that was restricted to a few mitochondria in small dendrites. In contrast, robust Rh-123 release into the cytosol was observed during seizure-like events (SLEs), indicating simultaneous depolarization of mitochondria. This was critically dependent on Ca2+ ion uptake and extrusion, because inhibition of the mitochondrial Ca2+ ion uniporter by Ru360 and the mitochondrial Na+/Ca2+ ion exchanger by 7-chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin- 2(3H)-one but not the inhibitor of mitochondrial permeability transition pore, cyclosporin A, decreased the SLE-associated mitochondrial depolarization.The Ca2+ ion dependence of simultaneous mitochondrial depolarization suggested enhanced Ca2+ ion cycling across mitochondrial membranes during epileptiform activity. Indeed, [Ca2+](m) fluctuated during interictal activity in single dendrites, and these fluctuations spread over the entire mitochondrial compartment during SLEs, as revealed using mitochondria-specific dyes (rhod-2 and rhod-ff) and spatial frequency-based image analysis. These findings strengthen the hypothesis that epileptic activity results in Ca2+ ion-dependent changes in mitochondrial function that might contribute to the neuronal injury during epilepsy.