Research Center of Neurology, Moscow, Russia.
Research Center of Neurology, Moscow, Russia; M.V. Lomonosov Moscow State University, Moscow, Russia.
J Trace Elem Med Biol. 2022 Sep;73:127012. doi: 10.1016/j.jtemb.2022.127012. Epub 2022 Jun 1.
Cadmium is a highly toxic heavy metal that is capable of accumulating in the body and causing neurodegeneration. However, the effect of other trace elements on Cd toxicity is currently poorly understood. The aim of this work was to study the effect of Zn and Cu ions on cadmium-induced death of neurons in the cerebral cortex.
The work was performed on rat cortical primary cultures. The MTT test was used to determine the cytotoxicity effects. Analysis of intracellular Ca concentration was assessed by the Fluo-4 AM calcium indicator that exhibit an increase in fluorescence upon binding Ca. MitoSOX Red (mitochondrial superoxide indicator) was used to measuring mitochondrial ROS content in live cells.
In this article, we show that the administration of CdCl (0.005-0.02 mM) for 48 h induced an increase in dose-dependent death rate of cultured cortical neurons. Mature neurons were more sensitive to the damaging effects of Cd than immature ones. ZnCl (0.01-0.03 mM) significantly protected neurons from this toxic effect. In contrast to ZnCl, CuCl (0.01 mM) increased cadmium neurotoxicity. Using Fluo-4 AM, measurements of intracellular calcium ions demonstrated that 24 h-exposure to Cd induced intensive increase in Fluo-4 fluorescence in neurons, which was significantly reduced by zinc ions. CuCl increased the cadmium-induced Fluo-4 and MitoSOX Red fluorescence in neurons. The chelator of intracellular Ca BAPTA significantly decreased Cd-induced intensive increase in Fluo-4 fluorescence in cells.
The data obtained by us indicate that Zn and Cu can affect the neurotoxicity of cadmium in different directions: Zn weaken the violation of intracellular calcium homeostasis caused by cadmium, preventing cell death, while Cu potentiate the increase in the level of free intracellular calcium induced by cadmium and the development of mitochondrial dysfunction with an increase in the production of free radicals in differentiated cultured neurons of the cerebral cortex, which ultimately stimulates cytotoxicity.
镉是一种毒性很强的重金属，能够在体内积累并导致神经退行性变。然而，目前人们对其他微量元素对镉毒性的影响知之甚少。本研究旨在探讨锌和铜离子对镉诱导大脑皮质神经元死亡的影响。
采用大鼠皮质原代培养细胞，MTT 法检测细胞毒性。通过 Fluo-4 AM 钙指示剂分析细胞内钙离子浓度，该指示剂与钙离子结合后荧光强度增加。MitoSOX Red（线粒体超氧化物指示剂）用于检测活细胞中线粒体 ROS 含量。
本文研究表明，48 小时内给予 0.005-0.02 mM 的 CdCl2 可诱导皮质神经元呈剂量依赖性死亡，成熟神经元对 Cd 的损伤作用比未成熟神经元更敏感。0.01-0.03 mM 的 ZnCl2 可显著保护神经元免受这种毒性作用。与 ZnCl2 相反，0.01 mM 的 CuCl2 增加了镉的神经毒性。用 Fluo-4 AM 测量细胞内钙离子后发现，24 小时暴露于 Cd 可使神经元内 Fluo-4 荧光显著增强，而锌离子可显著降低这种荧光强度。CuCl2 增加了镉诱导的 Fluo-4 和 MitoSOX Red 荧光强度。细胞内钙离子螯合剂 BAPTA 可显著降低细胞内 Fluo-4 荧光的增强。
我们的数据表明，Zn 和 Cu 可以以不同的方向影响 Cd 的神经毒性：Zn 减弱了 Cd 引起的细胞内钙离子稳态的破坏，从而阻止细胞死亡，而 Cu 增强了 Cd 诱导的游离细胞内钙离子水平的增加以及线粒体功能障碍的发展，伴随着自由基生成的增加，最终刺激了细胞毒性。
