In vitro investigation of zinc oxide nanoparticle toxic effects in spermatogonial cells at the molecular level

Because spermatogonia transmit genetic information across generations, their DNA must be protected from environmental damages, including exposure to zinc oxide nanoparticles (ZnO NPs), which are frequently used in modern technology. Here, we used an in vitro system enriched for spermatogonia and exposed them to 10 and 20 μg/ml ZnO NPs for one/seven days. We did not detect any significant cell death, chromosomal instability, or DNA fragmentation in the spermatogonia treated with the ZnO NPs following one-day treatment with 10 or 20 μg/ml ZnO NPs. However, ZnO NPs (both 10 and 20 μg/ml) induced chromosomal instability in the spermatogonia after seven days of treatment. Moreover, one-day exposure to these NPs induced reactive oxygen species (ROS) generation and upregulation of apoptotic pathway-related genes p53, Caspase3 and Il6, as an inflammatory factor. Taken together, our study provides preliminary evidence for possible damages induced by low concentrations of ZnO NPs in spermatogonia. We should pay increased attention when using these NPs because of the silent damages in spermatogonia that can be transmitted to the next generation and cause severe effects. However, more data and validation of these results are required to determine the extent of this concern.