Mechanisms of Polystyrene Microplastics in Multipathway Disruption of the Blood–Testis Barrier
Haoran Liu, Adila Adili, Hui Tian, Xiaofang HanABSTRACT
Background
Polystyrene microplastics (PS‐MPs) represent an emerging environmental pollutant, yet their potential threat to male reproductive health, specifically the integrity of the blood–testicular barrier (BTB), remains incompletely understood.
Objective
This study aimed to investigate the toxicological effects and underlying mechanisms of PS‐MPs exposure on testicular structure and BTB function in a mouse model.
Methods
Four‐week‐old male ICR mice were exposed to PS‐MPs at concentrations of 0, 500 µg/L, 5 mg/L, and 50 mg/L via drinking water for up to 5 weeks. Animals ( n = 10 per group per time point) were sacrificed at weeks 1, 2, 3, 4, and 5 after initiation of exposure. A comprehensive assessment was performed, including evaluation of BTB permeability via biotin tracing, analysis of key junction protein (Connexin43, ZO‐1, Occludin) expression and localization using western blot (WB), real‐time quantitative polymerase chain reaction (RT‐qPCR), and immunofluorescence, and immunofluorescent detection of macrophage activation (IBA‐1).
Results
PS‐MPs exposure significantly increased BTB permeability in a dose‐ and time‐dependent manner. This was accompanied by a marked downregulation in the expression and disrupted localization of Connexin43, ZO‐1, and Occludin. We observed an upregulation of IBA‐1 within the testis, indicating macrophage activation.
Conclusion
This study demonstrates that PS‐MPs induce BTB dysfunction in association with multipathway responses. Macrophage activation, as indicated by IBA‐1 upregulation, was closely associated with BTB injury and may represent a key component in this toxicological process, although its precise mechanistic role requires further investigation. These findings provide new insights into the reproductive toxicity of microplastics.