Cytosolic acidification and intracellular zinc release in hippocampal neurons
Cytosolic acidification and intracellular zinc release in hippocampal neurons
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DOI：
10.1111/j.1471-4159.2012.07695.x
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发表时间：
2012-05-01
影响因子：
4.7
通讯作者：
Kiedrowski, Lech
中科院分区：
文献类型：
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作者：
Kiedrowski, Lech
在暴露于谷氨酸的神经元中，Ca 2+内流通过一种尚不清楚的机制触发细胞内Zn 2+的释放。由于谷氨酸诱导Ca 2+依赖的胞质酸化，本工作测试了胞内Ca 2+浓度（[Ca 2 +]i）、胞内pH（pHi）和[Zn 2 +]i之间的关系。将培养的海马神经元暴露于谷氨酸和甘氨酸（Glu/Gly），同时分别使用FluoZin-3、Fura 2-FF和2 '，7'-双-（2-羧乙基）-5（6）-羧基荧光素监测[Zn 2 +]i、[Ca 2 +]i和pHi。正如预期的那样，应用Glu/Gly将pHi降低至6.1，并以Ca 2+依赖性方式诱导细胞内Zn 2+释放。pHi下降降低了FluoZin-3和Fura-2-FF对Zn 2+的亲和力。Glu/Gly诱导的[Zn ~（2+）]i升高速率与[Ca ~（2+）]i升高速率无相关性。相反，[Zn 2 +]i升高的程度与pHi下降的速率很好地对应。也就是说，[Zn 2 +]i增加更多的高度酸化的神经元。抑制Ca 2+依赖性pHi下降的机制（质膜Ca 2+泵和线粒体）抵消了Glu/Gly诱导的细胞内Zn 2+释放。碱性pH（8.5）抑制Glu/Gly诱导的细胞内Zn ~（2+）释放，而酸性pH（6.0）则增强其释放。pHi降至6.0（没有任何Ca ~（2+）内流或谷氨酸受体激活）导致细胞内Zn ~（2+）释放;释放的Zn ~（2+）（游离Zn ~（2+）加上与Fura-2FF和FluoZin-3结合的Zn ~（2+））达到1 μ M。
In neurons exposed to glutamate, Ca2+ influx triggers intracellular Zn2+ release via an as yet unclear mechanism. As glutamate induces a Ca2+-dependent cytosolic acidification, the present work tested the relationships among intracellular Ca2+ concentration ([Ca2+]i), intracellular pH (pHi), and [Zn2+]i. Cultured hippocampal neurons were exposed to glutamate and glycine (Glu/Gly), while [Zn2+]i, [Ca2+]i and pHi were monitored using FluoZin-3, Fura2-FF, and 2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein, respectively. Glu/Gly applications decreased pHi to 6.1 and induced intracellular Zn2+ release in a Ca2+-dependent manner, as expected. The pHi drop reduced the affinity of FluoZin-3 and Fura-2-FF for Zn2+. The rate of Glu/Gly-induced [Zn2+]i increase was not correlated with the rate of [Ca2+]i increase. Instead, the extent of [Zn2+]i elevations corresponded well to the rate of pHi drop. Namely, [Zn2+]i increased more in more highly acidified neurons. Inhibiting the mechanisms responsible for the Ca2+-dependent pHi drop (plasmalemmal Ca2+ pump and mitochondria) counteracted the Glu/Gly-induced intracellular Zn2+ release. Alkaline pH (8.5) suppressed Glu/Gly-induced intracellular Zn2+ release whereas acidic pH (6.0) enhanced it. A pHi drop to 6.0 (without any Ca2+ influx or glutamate receptor activation) led to intracellular Zn2+ release; the released Zn2+ (free Zn2+ plus Zn2+ bound to Fura-2FF and FluoZin-3) reached 1 mu M.