ZnO纳米粒子通过线粒体通路抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性的作用研究

氧化锌(ZnO)纳米粒子已被发现具有生物毒性,氧化应激被认为是最重要的因素之一。前期实验证实,ZnO纳米粒子能显著减少锰超氧化物歧化酶(Mn SOD)蛋白的表达,降低Mn SOD活性。本文通过检测乳酸脱氢酶(LDH)释放、线粒体活性氧(ROS)水平和膜电位(Δφm)、延迟整流钾电流变化和Na~+/K~+-ATP酶的表达及活性等变化,检测ZnO纳米粒子对小鼠光感受器细胞的细胞毒作用。结果表明,ZnO纳米粒子可显著增强小鼠光感受器细胞中LDH的释放、增加线粒体内ROS水平并下调Δφm、阻断延迟整流钾电流,同时降低Na~+/K~+-ATP酶的表达及活性,从而对小鼠视网膜光感受器细胞产生细胞毒作用,提示ZnO纳米粒子可通过线粒体通路引起氧化应激,从而抑制小鼠光感受器细胞Na~+/K~+-ATP酶表达和活性,产生细胞毒性,导致细胞死亡。本文的研究结果有助于理解ZnO纳米粒子引起细胞毒性的作用机理。

Inhibitory Effects of Zinc Oxide Nanoparticles on Na+/K+-ATP Enzyme Expression and Activity via Mitochondrial Pathway in Murine Photoreceptor Cells

Zinc oxide (ZnO) nanoparticles can exert toxic effect on organisms, and oxidative stress is regarded as one of the major factors. Nevertheless, the detailed mechanism of toxicity induced by ZnO nanoparticles has not yet been elucidated. This study aimed to investigate the toxic effects of ZnO nanoparticles on the expression and activity of Na⁺/K⁺-ATP enzyme and potassium channel block. Meanwhile, the effects of ZnO nanoparticles on murine photoreceptor cells including lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) level within mitochondria and mitochondrial membrane potential, delayed rectifier potassium current were further explored. Experimental results showed that ZnO nanoparticles can significantly enhance the expressions of LDH, increase the intracellular ROS levels, collapse the mitochondrial membrane potential, block the delayed rectifier potassium current, and reduce the Na⁺/K⁺-ATP enzyme expressions at mRNA and protein levels and inhibit their activities. ZnO nanoparticles can exert oxidative stress via mitochondria pathway, inhibit the expression and activity of Na⁺/K⁺-ATP enzyme, thereby exhibiting cytotoxicity and leading to cell death. The present study will facilitate the understanding the mechanism of ZnO nanoparticle-induced cytotoxicity on murine photoreceptor cells.