Polystyrene Microplastics Induce Oxidative Stress in Mouse Hepatocytes in Relation to Their Size

Microplastics have become a new type of environmental pollutant that can accumulate in various tissues and organs of the body and cause chronic damage. In this study, two different size polystyrene microplastics (PS-MPs, 5 μm and 0.5 μm) exposure models were established in mice to investigate the effects of PS-MPs with different particle sizes on oxidative stress in the liver. The results showed that PS-MPs exposure caused a decrease in body weight and liver-to-body weight. The hematoxylin and eosin staining and transmission electron microscopy results showed that exposure to PS-MPs led to the disorganized cellular structure of liver tissue, nuclear crinkling, and mitochondrial vacuolation. The extent of damage in the 5 μm PS-MP exposure group was more extensive when compared with the other group. The evaluation of oxidative-stress-related indicators showed that PS-MPs exposure exacerbated oxidative stress in hepatocytes, especially in the 5 μm PS-MPs group. The expression of oxidative-stress-related proteins sirtuin 3(SIRT3) and superoxide dismutase (SOD2) was significantly reduced, and the reduction was more pronounced in the 5 μm PS-MPs group. In conclusion, PS-MPs exposure led to oxidative stress in mouse hepatocytes and caused more severe damage in the 5 μm PS-MPs group when compared with the 0.5 μm PS-MPs group.