In vitro cytotoxicity of zinc oxide nanoparticles in mouse ovarian germ cells

Recently, metal oxide nanoparticles such as zinc oxide nanoparticles (ZnO-NPs) have received considerable attention and humans are exposed to them in everyday life. The increasing use of ZnO-NPs may lead to human health issues. However, little is known about their effects on female reproductive systems, particularly on female germ cells. Germ cells differentiation is a complex biological process that is sensitive to environmental insults and any negative effect on germ cells development may inhibit fertility. Therefore, this study aimed to determine the impact of ZnO-NPs on mouse ovarian germ cells in an in vitro system. The effects of ZnO-NPs on these cells were evaluated using light microscopy, cell proliferation assessment, reactive oxygen species (ROS) level determination, standard cytotoxicity assessment (cell viability assessed by PI staining) and gene expression analysis. Our results demonstrated that ZnO-NPs have cytotoxic effects in a concentration- and time-dependent manner in mouse ovarian germ cells. Exposure of cells to ZnO-NPs concentration-dependently enhanced ROS generation. Furthermore, molecular analysis of ZnO-NPs-treated cells showed a significant increase in expression of premeiotic germ cells markers but a decrease in meiotic and post-meiotic markers compared to un-treated cells. Taken together, our data provides a preliminary insight into possible adverse effects of ZnO-NPs on mouse ovarian germ cells differentiation even at low concentrations.