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

Abstract

Cerium oxide nanoparticles (CeO2NPs) 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 CeO2NPs 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 μg/mL CeO2NPs for 5 days. We observed that CeO2NPs significantly reduced the number of undifferentiated and differentiated germ cells in MTFs in a dose-dependent manner. Compared with the control, CeO2NPs downregulated expression levels of both undifferentiated and differentiated germ cell marker genes. Although treatment with 10–30 μg/mL CeO2NPs did not alter Sertoli cell numbers, 50 μg/mL CeO2NP 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 μg/mL CeO2NPs when compared with those exposed to other treatments. Exposure of MTFs to 50 μg/mL CeO2NPs decreased mRNA expression levels of steroidogenic enzymes, such as Cyp17α1 and HSD3b1. Furthermore, the expression of Insl3, a Leydig cell-specific marker gene, decreased with increasing CeO2NP concentrations, although interstitial cells were still observed in MTFs exposed to 50 μg/mL CeO2NPs. Collectively, our findings revealed that CeO2NPs 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.