Effect of zinc and copper ions on cadmium-induced toxicity in rat cultured cortical neurons.

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.