Short term exposure to polystyrene nanoplastics in mice evokes self-regulation of glycolipid metabolism

With the detection of nano-plastics (NPs) in daily essentials and drinking water, the potential harm of NPs to human health has become the focus of global attention. Studies have shown that long term exposure to NPs can lead to disorders of glucose and lipid metabolism in organisms, while the effects of short term exposure are rarely reported. Moreover, environmental factors cause the aging of NPs, and it is unclear whether this has an effect on their toxicity. In this study, we use 100 nm polystyrene (PS) NPs and ultraviolet (UV) aging PS (aPS) NPs to gavage mice for 7 days at an exposure dose of 50 mg/kg/day. To evaluate the effects of exposure on mice hepatic glucose lipid metabolism, we performed blood biochemical, pathological and metabolomic analyses. The results showed that exposure to PS NPs and aPS NPs increased serum glucose, disrupted serum lipoprotein levels, and up-regulated the expression levels of phosphatidylinositol 3-kinase (PI3K)/ phosphoprotein kinase B (p-AKT)/Glucose transporter 4 (GLUT4) proteins in the glucose metabolism pathway. The expression levels of key proteins sterol regulatory element binding protein-1 (SREBP-1)/peroxisome proliferator-activated receptor-γ (PPARγ)/adipose triglyceride lipase (ATGL) in the lipid metabolism signaling pathway were significantly increased. These findings suggest that short term exposure to PS NPs and aPS NPs induces glycolipid metabolism disturbance in mice, which may subsequently awaken the mice to self-regulate the serum levels of various lipoproteins and the expression of related key proteins. Compared with PS NPs, the aPS NPs interfered more strongly with glucose metabolism, and the corresponding self-regulation in mice was also more obvious. These findings not only provide a basis for environmental factors to increase the health risk of NPs but also provided a reference for the selection of test substances for further studies on the toxicity of NPs.