Cytosolic phospholipase A2 alpha mediates electrophysiologic responses of hippocampal pyramidal neurons to neurotoxic NMDA treatment
Cytosolic phospholipase A2 alpha mediates electrophysiologic responses of hippocampal pyramidal neurons to neurotoxic NMDA treatment
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DOI：
10.1073/pnas.0605427104
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发表时间：
2007-04
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影响因子：
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通讯作者：
Ying Shen;K. Kishimoto;D. Linden;A. Sapirstein
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作者：
Ying Shen;K. Kishimoto;D. Linden;A. Sapirstein
花生四烯酸生成酶胞浆磷脂酶A2 α（cPLA 2 α）与兴奋性毒性神经元损伤的进展有关。然而，cPLA 2 α毒性的机制尚未确定。在这里，我们使用了将小鼠海马切片暴露于NMDA作为兴奋性毒性损伤的模型系统，并结合CA 1锥体神经元的同步膜片钳记录和共聚焦Ca 2+成像。NMDA处理对野生型（WT）CA 1神经元的损伤显著大于cPLA 2 α缺失的CA 1神经元。在电压钳位神经元（由NMDA受体介导的和其他电导组成）中，NMDA的浴应用诱发了缓慢的内向电流，cPLA 2 α null中的内向电流小于WT切片。这不是由于NMDA受体功能的下调，因为NMDA受体介导的电流在每个基因型的笼状谷氨酸短暂光解后是相等的。电流钳记录过程中和NMDA暴露后，引发一个单一的动作电位与一个简短的电流注入。NMDA暴露后，WT CA 1神经元产生了棘波诱发的平台电位和增加的棘波诱发的树突状细胞钙瞬变。cPLA 2 α敲除小鼠的CA 1神经元和用cPLA 2 α抑制剂处理的WT神经元中不存在这些效应。Ca敏感性K通道毒素apamin和paxilline在WT和cPLA 2 α null切片中引起峰电位增宽和Ca 2+增强。WT中的NMDA应用和cPLA 2 α无效细胞中的花生四烯酸应用阻断了apamin/paxilline的作用。这些结果表明，cPLA 2 α活性是NMDA受体激活触发的异常电生理事件发生所必需的，部分原因是K通道功能减弱。
The arachidonic acid-generating enzyme cytosolic phospholipase A2 alpha (cPLA2α) has been implicated in the progression of excitotoxic neuronal injury. However, the mechanisms of cPLA2α toxicity have yet to be determined. Here, we used a model system exposing mouse hippocampal slices to NMDA as an excitotoxic injury, in combination with simultaneous patch-clamp recording and confocal Ca2+ imaging of CA1 pyramidal neurons. NMDA treatment caused significantly greater injury in wild-type (WT) than in cPLA2α null CA1 neurons. Bath application of NMDA evoked a slow inward current in voltage-clamped neurons (composed of both NMDA receptor-mediated and other conductances) that was smaller in cPLA2α null than in WT slices. This was not due to down-regulation of NMDA receptor function because NMDA receptor-mediated currents were equivalent in each genotype following brief photolysis of caged glutamate. Current-clamp recordings were made during and following NMDA exposure by eliciting a single action potential with a brief current injection. After NMDA exposure, WT CA1 neurons developed a spike-evoked plateau potential and an increased spike-evoked dendritic Ca2+ transient. These effects were absent in CA1 neurons from cPLA2α null mice and WT neurons treated with a cPLA2α inhibitor. The Ca-sensitive K-channel toxins, apamin and paxilline, caused spike broadening and Ca2+ enhancement in WT and cPLA2α null slices. NMDA application in WT and arachidonate applied to cPLA2α null cells occluded the effects of apamin/paxilline. These results indicate that cPLA2α activity is required for development of aberrant electrophysiologic events triggered by NMDA receptor activation, in part through attenuation of K-channel function.