Microplastics (MPs) and nanoplastics (NPs) widely exist in human living environment and enter the body through water, food chain and breathing. Several studies have shown that MPs or NPs disrupt the blood-testis barrier in rodents. However, the molecular mechanism by which MPs and NPs damage the blood-testis barrier remains unclear. In the present study, our aim was to investigate the molecular mechanism of the destruction of blood-testis barrier induced by polystyrene (PS)-NPs. Mice were treated with 50 μg/kg·day PS-NPs by tail vein injection once daily for two consecutive days. The results showed that PS-NPs exposure significantly decreased the levels of tight junction (TJ) proteins ZO-2, occludin and claudin-11 in testis of mice. In vitro, we used TM4 Sertoli cells to explore the underlying mechanism of the decrease in TJ proteins induced by PS-NPs. We found that PS-NPs activated IRE1α and induced its downstream XBP1 splicing, which in turn elevated the expression of the E3 ubiquitin ligase CHIP, then CHIP triggers proteasomal degradation of ZO-2, occludin, and claudin-11 proteins. Our findings suggest that IRE1α/XBP1s/CHIP pathway is a pivotal mechanism of TJ proteins degradation induced by PS-NPs in mouse Sertoli cells. In conclusion, our results reveal that the degradation of TJ proteins is one of the mechanisms of blood-testis barrier destruction caused by acute exposure to PS-NPs.

Bisphenol A (BPA), extensively utilized in the manufacture of epoxy resins and polycarbonate plastics, is prevalent in the environment. Its exposure has been associated with an increased risk of hepatic lesions; however, the underlying mechanisms and the spectrum of its effects remain poorly understood. This study investigates the role of the Keap1-Nrf2 signaling pathway in regulating BPA-induced hepatotoxicity in vivo using a rat model. Over a 30-day period, rats were orally administered either corn oil or BPA (0.5, 5, and 50 mg/kg). Changes in hepatic and kidney histology were assessed via transmission electron microscopy and HE staining. Oxidative stress levels in the liver tissue and serum were quantified, while the mRNA expression of Nrf2, Keap1, GPX2, HO-1, and caspase-3 was evaluated using qRT-PCR. Additionally, the expression of Nrf2 and cleaved caspase-3 in the liver tissue was measured through immunohistochemistry and Western blotting. Results indicated that BPA exposure significantly reduced the liver and adrenal coefficients in the treated rats compared to controls. Notable histomorphological alterations were observed in the liver and kidney tissues of the BPA-treated rats. The serum levels of GOT and TNF-α were significantly elevated in the BPA group relative to the controls. Evidence of oxidative stress was supported by increased malondialdehyde levels and decreased total superoxide dismutase activity in the liver and kidney, alongside a reduction in glutathione peroxidase activity in the liver tissue. Furthermore, BPA exposure enhanced the mRNA expression levels of Nrf2, Keap1, GPX2, HO-1, and caspase-3 in the liver tissue. Concurrently, Nrf2 and cleaved caspase-3 expression levels were elevated in the BPA-treated group compared to the controls. These findings suggest that BPA may contribute to metabolic disorders of liver function and poses a hepatotoxicity risk. Moreover, the activation of the Keap1-Nrf2 pathway may offer protective effects against hepatotoxicity, with potential implications for human liver disease.