Time course assessment of methylmercury effects on C6 glioma cells: Submicromolar concentrations induce oxidative DNA damage and apoptosis
Time course assessment of methylmercury effects on C6 glioma cells: Submicromolar concentrations induce oxidative DNA damage and apoptosis
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DOI：
10.1002/jnr.10419
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发表时间：
2002-12-01
影响因子：
4.2
通讯作者：
Gatti, R
中科院分区：
文献类型：
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作者：
Belletti, S;Orlandini, G;Gatti, R
有机汞是一种众所周知的神经毒物，但其作用机制尚未完全阐明。除了对神经元的直接影响外，许多实验证据也支持神经胶质成分的参与。我们评估了暴露在 10(-5)-10(-8) M 范围内的神经胶质模型、C6 神经胶质瘤细胞中氢氧化甲基汞 (MeHgOH) 的毒性。通过延时共焦显微镜研究了效应的时间进程，并补充了生化数据。我们监测了细胞活力和增殖率、活性氧 (ROS)、线粒体跨膜电位、DNA 氧化、能量代谢和细胞死亡方式。最早的影响是可测量的 ROS 产生，随后是氧化 DNA 损伤，同时伴有部分线粒体去极化。对细胞活力的影响是剂量依赖性的。 TUNEL、caspase活性和钙黄绿素负载细胞的实时形态学观察表明，细胞凋亡是该浓度范围内唯一可检测到的细胞死亡模式。 N-乙酰半胱氨酸 (NAC) 或还原型谷胱甘肽 (GSH) 完全阻止 MeHgOH 的细胞凋亡作用。产生ROS和DNA OH加合物的最低有效MeHgOH浓度为10(-7) M。亚微摩尔浓度的 MeHgOH 对 C6 细胞的影响可能与低剂量、长期接触（例如食物来源的接触）引起的发育神经毒性有关。此外，我们还表明，相同的浓度可有效诱导 DNA 氧化损伤，并具有进一步的潜在致病影响。 (C) 2002 Wiley-Liss, Inc.
Organic mercury is a well-known neurotoxicant although its mechanism of action has not been fully clarified. In addition to a direct effect on neurons, much experimental evidence supports an involvement of the glial component. We assessed methylmercury hydroxide (MeHgOH) toxicity in a glial model, C6 glioma cells, exposed in the 10(-5)-10(-8) M range. The time course of the effects was studied by time-lapse confocal microscopy and supplemented with biochemical data. We have monitored cell viability and proliferation rate, reactive oxygen species (ROS), mitochondrial transmembrane potential, DNA oxidation, energetic metabolism and modalities of cell death. The earliest effect was a measurable ROS generation followed by oxidative DNA damage paralleled by a partial mitochondrial depolarization. The effect on cell viability was dose dependent. TUNEL, caspase activity and real-time morphological observation of calcein-loaded cells showed that apoptosis was the only detectable mode of cell death within this concentration range. N-acetyl-cysteine (NAC) or reduced glutathione (GSH) completely prevent the apoptotic effect of MeHgOH. The lowest effective MeHgOH concentration was 10(-7) M for ROS and DNA OH-adducts generation. The effect of submicromolar concentrations of MeHgOH on C6 cells could be relevant in the developmental neurotoxicity caused by low dose, long-term exposures, such as those of food origin. In addition, we have shown that the same concentrations are effective in the induction of DNA oxidative damage, with further potential pathogenetic implications. (C) 2002 Wiley-Liss, Inc.