Reproductive toxicity of polystyrene microplastics: In vivo experimental study on testicular toxicity in mice

Microplastics (MPS) are widespread in our environment and have a potential impact on the reproductive development of humans and mammals. In this study, we evaluated the effect of 5 µm polystyrene microplastics(PS-MPS) on spermatogenesis in mice. The damage by PS-MPS to epididymal sperm was studied using blood cell counts. The results showed that the number of viable epididymis sperm after PS-MPS exposure was significantly reduced. Using Duff-Quik staining, we found that the PS-MPS exposure increased the rate of sperm deformity. The testis is an important organ responsible for normal spermatogenesis. HE and TUNEL staining showed atrophy, shedding, and apoptosis of sperm cells at all levels of the testis after exposure to PS-MPS. Western blot and qPCR analysis were used to detect Nrf2/HO-1 and NF-κB. The results showed that after PS-MPS exposure, the expression of the pro-inflammatory molecule NF-κB and that of the inflammatory factors interleukin (IL)-1β and IL-6 increased significantly, whereas that of the anti-inflammatory molecule Nrf2/HO-1 decreased. These results indicate that the abnormal sperm quality in ICR mice caused by PS-MPS exposure is closely related to the Nrf2/HO-1/NF-κB pathway.