Mild acidosis enhances AMPA receptor-mediated intracellular zinc mobilization in cortical neurons
Mild acidosis enhances AMPA receptor-mediated intracellular zinc mobilization in cortical neurons
复制标题
DOI：
10.2119/2007-00047.frazzini
复制
发表时间：
2007-07-01
影响因子：
5.7
通讯作者：
Sensi, Stefano L.
中科院分区：
文献类型：
--
作者：
Frazzini, Valerio;Rapposelli, Ilario G.;Sensi, Stefano L.
谷氨酸受体的过度激活和随后的神经元内钙（（Ca（2+））（1））水平的失调是脑缺血引发的损伤性通路的关键组成部分。中风的另一个标志是实质性酸中毒，我们以前已经证明，轻度酸中毒可以作为一个开关，以减少NMDAR依赖的神经元损失，同时增强AMPAR介导的神经元损失。在酸中毒环境中AMPAR介导的神经元死亡的增强最初仅与（Ca 2+），稳态失调相关，如通过Ca 2+成像评估的;然而，另一种二价阳离子Zn 2+的细胞内稳态失调最近已成为缺血性神经元损伤中的另一个重要辅因子。（Zn ~（2+）~（1+））的增加对Ca ~（2+）敏感的荧光探针的荧光变化有很大的贡献，Ca ~（2+）敏感的荧光探针对Zn ~（2+）也有很大的亲和力。因此，我们重新审视了我们最初的发现（Mcdonald等人，1998）并研究我们观察到的AMPAR介导的fura-2信号是否也可能部分归因于（Zn 2+）（1）的增加。将载有Fura-2的神经元培养物暴露于在pH 7.4的生理缓冲液中的AMPAR激动剂红藻氨酸盐，然后在pH 7.4或pH 6.2下洗涤。在两种pH下观察到fura-2信号的延迟恢复。有趣的是，发现这种受损的恢复期对细胞内Zn 2+的螯合敏感。用Zn 2+敏感（和Ca（2+）不敏感）荧光探针FluoZin-3的实验证实了AMPAR激活增加（Zn 2+）的想法，这是一种通过轻度酸中毒增强的现象。此外，我们的研究结果表明，选择性Ca 2+成像要求使用细胞内重金属螯合剂，以避免内源性金属，如Zn 2+的混淆效应。
Overactivation of glutamate receptors and subsequent deregulation of the intraneuronal calcium ((Ca (2+))(1)) levels are critical components of the injurious pathways initiated by cerebral ischemia. Another hallmark of stroke is parenchymal acidosis, and we have previously shown that mild acidosis can act as a switch to decrease NMDAR-dependent neuronal loss while potentiating the neuronal loss mediated by AMPARs. Potentiation of AMPAR-mediated neuronal death in an acidotic environment was originally associated only with (Ca2+), dyshomeostasis, as assessed by Ca2+ imaging; however, intracellular dyshomeostasis of another divalent cation, Zn2+, has recently emerged as another important co-factor in ischemic neuronal injury. Rises in(Zn2+)1 greatly contribute to the fluorescent changes of Ca2+-sensitive fluorescent probes, which also have great affinity for Zn2+. We therefore revisited our original findings (Mcdonald et al., 1998) and investigated if AMPAR-mediated fura-2 signals we observed could also be partially due to (Zn2+)(1) increases.Fura-2 loaded neuronal cultures were exposed to the AMPAR agonist, kainate, in a physiological buffer at pH 7.4 and then washed either at pH 7.4 or pH 6.2. A delayed recovery of fura-2 signals was observed at both pHs. Interestingly this impaired recovery phase was found to be sensitive to chelation of intracellular Zn2+. Experiments with the Zn2+ sensitive (and Ca(2+ -)insensitive) fluorescent probe FluoZin-3 confirmed the idea that AMPAR activation increases (Zn2+), a phenomenon that is potentiated by mild acidosis. Additionally, our results show that selective Ca 2+ imaging mandates the use of intracellular heavy metal chelators to avoid confounding effects of endogenous metals such as Zn2+.