Toxicity of cerium oxide nanoparticles on neonatal testicular development in mouse organ culture

Cerium oxide nanoparticles (CeO(2)NPs) are lanthanide element oxides widely used in industrial processes, and environmental exposure to these nanomaterials highlights the potential risks to human health. In the present study, we evaluated the toxicity of CeO(2)NPs in neonatal mouse testes using in vitro organ cultures. Mouse testicular fragments (MTFs) derived from 5-day postpartum mouse testes were exposed to 0-50 mu g/mL CeO(2)NPs for 5 days. We observed that CeO(2)NPs significantly reduced the number of undifferentiated and differentiated germ cells in MTFs in a dose-dependent manner. Compared with the control, CeO(2)NPs downregulated expression levels of both undifferentiated and differentiated germ cell marker genes. Although treatment with 10-30 mu g/mL CeO(2)NPs did not alter Sertoli cell numbers, 50 mu g/mL CeO(2)NPs reduced the cell number and mRNA expression of Sox9 and AMH in MTFs. Accordingly, protein levels of Sox9 were also reduced in MTFs exposed to 50 mu g/mL CeO(2)NPs when compared with those exposed to other treatments. Exposure of MTFs to 50 mu g/mL CeO(2)NPs decreased mRNA expression levels of steroidogenic enzymes, such as Cyp17 alpha 1 and HSD3b1. Furthermore, the expression of Insl3, a Leydig cell-specific marker gene, decreased with increasing CeO(2)NPs concentrations, although interstitial cells were still observed in MTFs exposed to 50 mu g/mL CeO(2)NPs. Collectively, our findings revealed that CeO(2)NPs could negatively impact prepubertal spermatogenesis and germ cell maintenance via germ cell depletion, and high doses could damage Sertoli cells and disturb steroidogenesis in MTFs.