Hexachloronaphthalene (PCN67) is one of the most toxic among polychlorinated naphthalenes. Despite the known high bioaccumulation and persistence of PCN67 in the environment, it is still unclear to what extent exposure to these substances may interfere with normal neuronal physiology and lead to neurotoxicity. Therefore, the primary goal of this study was to assess the effect of PCN67 in neuronal in vitro models. Neuronal death was assessed upon PCN67 treatment using differentiated PC12 cells and primary hippocampal neurons. At 72 h postexposure, cell viability assays showed an IC₅₀ value of 0.35 μg/ml and dose-dependent damage of neurites and concomitant downregulation of neurofilaments L and M. Moreover, we found that younger primary neurons (DIV4) were much more sensitive to PCN67 toxicity than mature cultures (DIV14). Our comprehensive analysis indicated that the application of PCN67 at the IC₅₀ concentration caused necrosis, which was reflected by an increase in LDH release, HMGB1 protein export to the cytosol, nuclear swelling, and loss of homeostatic control of energy balance. The blockage of mitochondrial calcium uniporter partially rescued the cell viability, loss of mitochondrial membrane potential (ΔΨ_m), and the overproduction of reactive oxygen species, suggesting that the underlying mechanism of neurotoxicity involved mitochondrial calcium accumulation. Increased lipid peroxidation as a consequence of oxidative stress was additionally seen for 0.1 μg/ml of PCN67, while this concentration did not affect ΔΨ_m and plasma membrane permeability. Our results show for the first time that neuronal mitochondria act as a target for PCN67 and indicate that exposure to this drug may result in neuron loss via mitochondrial-dependent mechanisms.

中文翻译：

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六氯萘通过增强活性氧的产生机制诱导线粒体依赖性神经毒性。

六氯萘（PCN67）是多氯萘中毒性最高的一种。尽管已知PCN67在环境中具有很高的生物蓄积性和持久性，但仍不清楚这些物质的暴露在多大程度上会干扰正常的神经元生理并导致神经毒性。因此，这项研究的主要目的是评估PCN67在体外神经元模型中的作用。使用分化的PC12细胞和原代海马神经元在PCN67治疗后评估神经元死亡。暴露后72小时，细胞活力分析显示IC ₅₀值为 0.35μ克/毫升和神经突的剂量依赖性损伤以及随之而来的神经丝L和M的下调。此外，我们发现年轻的原代神经元（DIV4）对PCN67毒性的敏感性比成熟培养物（DIV14）高得多。我们的综合分析表明，在IC ₅₀浓度下应用PCN67会导致坏死，这可通过LDH释放增加，HMGB1蛋白输出到细胞质，核肿胀以及失去能量平衡的稳态控制来反映。线粒体钙单向转运体的堵塞部分救出细胞活力，线粒体膜电位的损失（ΔΨ_米）以及活性氧的过度生产，表明神经毒性的潜在机制涉及线粒体钙的积累。增加的脂质过氧化作为氧化应激的结果被加看到0.1  μ微克/毫升PCN67，而该浓度不影响ΔΨ_米和质膜通透性。我们的结果首次显示神经元线粒体充当PCN67的靶标，并表明接触该药物可能通过线粒体依赖性机制导致神经元丢失。