AMPA exposures induce mitochondrial Ca2+ overload and ROS generation in spinal motor neurons in vitro
AMPA exposures induce mitochondrial Ca2+ overload and ROS generation in spinal motor neurons in vitro
复制标题
DOI：
10.1523/jneurosci.20-01-00240.2000
复制
发表时间：
2000-01-01
影响因子：
5.3
通讯作者：
Weiss, JH
中科院分区：
文献类型：
--
作者：
Carriedo, SG;Sensi, SL;Weiss, JH
肌萎缩侧索硬化症（ALS）中运动神经元选择性脆弱的原因主要是未知的。一个可能的因素是运动神经元的Ca 2+渗透性AMPA/红藻氨酸通道的表达，这可能允许响应于突触受体激活的快速Ca 2+内流。然而，中枢神经元的其他亚群，最显著的是前脑GABA能中间神经元，始终表达大量的这些通道，但在ALS中不退化。事实上，当受到相同的兴奋性毒性暴露时，运动神经元比GABA能神经元更容易受到AMPA/红藻氨酸受体介导的神经毒性的影响。进行了显微荧光研究，以审查脆弱性差异的基础。首先，AMPA或红藻氨酸暴露似乎触发运动神经元中的大量线粒体Ca 2+负载，如激动剂暴露后添加线粒体解偶联剂羰基氰化物对-（三氟甲氧基）苯腙（FCCP）后细胞内Ca 2+急剧增加所示。相同的暴露导致GABA能皮质神经元中线粒体Ca 2+积聚很少。随后的实验检查了线粒体功能的其他措施，以比较这些人群之间AMPA/红藻氨酸受体激活的后遗症。短暂暴露于AMPA或红藻氨酸引起的线粒体去极化，使用四甲基罗丹明乙酯，和活性氧（ROS）的产生，使用hydroethidine，在运动神经元中进行评估。然而，这些作用仅见于暴露于非脱敏AMPA受体激动剂红藻氨酸后的GABA能神经元。最后，添加抗氧化剂或毒素（FCCP或CN-），阻止线粒体Ca 2+摄取减弱AMPA/红藻氨酸受体介导的运动神经元损伤，表明线粒体Ca 2+摄取和随后的ROS产生是损伤过程的核心。
The reason for the selective vulnerability of motor neurons in amyotrophic lateral sclerosis (ALS) is primarily unknown. A possible factor is the expression by motor neurons of Ca2+-permeable AMPA/kainate channels, which may permit rapid Ca2+ influx in response to synaptic receptor activation. However, other subpopulations of central neurons, most notably forebrain GABAergic interneurons, consistently express large numbers of these channels but do not degenerate in ALS. Indeed, when subjected to identical excitotoxic exposures, motor neurons were more susceptible than GABAergic neurons to AMPA/kainate receptor-mediated neurotoxicity. Microfluorimetric studies were performed to examine the basis for the difference in vulnerability. First, AMPA or kainate exposures appeared to trigger substantial mitochondrial Ca2+ loading in motor neurons, as indicated by a sharp increase in intracellular Ca2+ after addition of the mitochondrial uncoupler carbonyl cyanide p-(trifluoromethoxy)phenyl hydrazone (FCCP) after the agonist exposure. The same exposures caused little mitochondrial Ca2+ accumulation in GABAergic cortical neurons. Subsequent experiments examined other measures of mitochondrial function to compare sequelae of AMPA/kainate receptor activation between these populations. Brief exposure to either AMPA or kainate caused mitochondrial depolarization, assessed using tetramethylrhodamine ethylester, and reactive oxygen species (ROS) generation, assessed using hydroethidine, in motor neurons. However, these effects were only seen in the GABAergic neurons after exposure to the nondesensitizing AMPA receptor agonist kainate. Finally, addition of either antioxidants or toxins (FCCP or CN-) that block mitochondrial Ca2+ uptake attenuated AMPA/kainate receptor-mediated motor neuron injury, suggesting that the mitochondrial Ca2+ uptake and consequent ROS generation are central to the injury process.