Routes of zinc entry in mouse cortical neurons: role in zinc‐induced neurotoxicity
Routes of zinc entry in mouse cortical neurons: role in zinc‐induced neurotoxicity
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DOI：
10.1046/j.1460-9568.2000.00875.x
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发表时间：
2000-01
影响因子：
3.4
通讯作者：
P. Marin;M. Israël;J. Glowinski;J. Prémont
中科院分区：
文献类型：
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作者：
P. Marin;M. Israël;J. Glowinski;J. Prémont
中枢神经元暴露于Zn 2+会触发神经元死亡。使用特异性Zn 2+荧光染料N-（6-甲氧基-8-喹啉基）-对甲苯磺酰胺（TSQ）在小鼠的活皮质神经元中研究了Zn 2+进入的途径，TSQ优先检测膜结合的Zn 2+。将皮层神经元暴露于浓度递增的Zn ~（2+）（1-100 μm）中，可引起TSQ荧光强度的递增。此荧光信号不被毛地黄皂苷渗透质膜所减弱。因此，TSQ荧光的主要部分（三分之二）与暴露于Zn 2+的皮质神经元的颗粒部分相关。这些结果表明，在神经元中用TSQ检测到的Zn 2+主要与膜结合。在暴露于3 μ mZn 2+的神经元中测量的TSQ荧光被Na+-吡啶并[2-（3-羟基-5-甲基异恶唑-4-丙酸）]、α-氨基-3-羟基-5-甲基异恶唑-4-丙酸（AMPA）、N-甲基-d-天冬氨酸（NMDA）或KCl诱导的去极化增强。然而，在没有任何处理的情况下，暴露于3 μm Zn 2+的神经元的TSQ标记仅被NMDA受体拮抗剂降低，而在AMPA受体或L型电压门控Ca 2+通道的拮抗剂存在下，TSQ标记保持不变。通过NMDA受体的Zn 2+进入不会导致Zn 2+诱导的神经元死亡，因为只有在Zn 2+暴露后加入NMDA受体拮抗剂时，才能阻止Zn 2+诱导的神经元死亡。最后，Zn 2+诱导细胞外谷氨酸的延迟积累，这可能是负责延迟NMDA受体激活，导致神经元死亡。
Exposure of central neurons to Zn2+ triggers neuronal death. The routes of Zn2+ entry were investigated in living cortical neurons from the mouse using the specific Zn2+ fluorescent dye N‐(6‐methoxy‐8‐quinolyl)‐p‐toluene sulphonamide (TSQ), which preferentially detects membrane‐bound Zn2+. Exposure of cortical neurons to increasing concentrations of Zn2+ (1–100 μm) induced a progressive increase in the fluorescence of TSQ. This fluorescence signal was not attenuated by the permeation of plasma membrane with digitonin. Accordingly, the major part of TSQ fluorescence (two‐thirds) was associated to the particulate fraction of cortical neurons exposed to Zn2+. These results suggest that Zn2+ detected with TSQ in neurons is mainly bound to membranes. TSQ fluorescence measured in neurons exposed to 3 μm Zn2+ was enhanced by Na+‐pyrithione, a Zn2+ ionophore, α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid (AMPA), N‐methyl‐d‐aspartate (NMDA) or KCl‐induced depolarization. However, in the absence of any treatment, TSQ labelling of neurons exposed to 3 μm Zn2+ was only decreased by NMDA receptor antagonists, whereas it remained unaltered in the presence of antagonists of AMPA receptors or L‐type voltage‐gated Ca2+ channels. Zn2+ entry through NMDA receptors did not contribute to Zn2+‐induced neuronal death, as it was prevented by antagonists of NMDA receptors only when they were added after the Zn2+ exposure. Finally, Zn2+ induced a delayed accumulation of extracellular glutamate which might be responsible for the delayed NMDA receptor activation that leads to neuronal death.