Reproductive Toxicity of Chronic Exposure To Polystyrene Microplastics And The Molecular Mechanism of Decrease In Testosterone Levels In Male Mice

Abstract Background: Microplastics (MPs), which are smaller in size and difficult to degrade, can be easily ingested by marine life and enter mammals including human through the food chain. Previous study has demonstrated that acute exposure to MPs induced a reduction of testosterone levels and finally resulted in male reproductive toxicity. Therefore, assessing the harm that MPs dose to the male reproductive system under long-term exposure of environmental concentrations and comprehending the mechanism from cell and molecularlevels are necessary. Results: We affirmed that male reproductive toxicity of chronic exposure to polystyrene MPs (PS-MPs) in environmental pollution concentrations and explored the underlying mechanism of MPs-induced decrease of testosterone in mice. Polystyrene MPs (PS-MPs) treatment resulted in the destruction of testicular histology, abnormal spermatogenesis, and interference of hormone secretion in serum. PS-MPs induced a reduction of testosterone levels through downregulation of LH-mediated LHR/cAMP/PKA/StAR pathway. Moreover, we discovered that PS-MPs attached to and became internalized by Leydig cells. Conclusions: In summary, our study showed that PS-MPs existed toxicity to male reproduction under long-term exposure and environmental pollution concentrations, and these potential hazards may ring alarm bells of public health. As well, the discussing of molecular mechanisms may be instructive to search novel therapeutic targets.