Polystyrene nanoplastics aggravate reproductive system damage in obese male mice by perturbation of the testis redox homeostasis.

The potential impact of the combination of a high-fat diet (HFD) and polystyrene nanoplastics (PS-NPs) on fertility cannot be ignored, especially when the fertility rate is declining. However, it has not attracted considerable attention. In this study, an obese mouse model was established using an HFD, and the reproductive function of male mice was evaluated after intragastric administration of 100 μL of a 10 mg/mL PS-NP suspension for 4 weeks. By determining the morphology and vitality of sperm and related indicators of testosterone production, it was found that PS-NPs aggravated the destruction of sperm mitochondrial structure, decrease sperm activity, and testosterone production in HFD-fed mice. To comprehensively analyze the injury mechanism, the integrity of the blood testicular barrier (BTB) and the function of Leydig and Sertoli cells were further analyzed. It was found that PS-NPs could destroy BTB, promote the degeneration of Leydig cells, reduce the number of Sertoli cells, and decrease lactate secretion in HFD-fed mice. PS-NPs further interfered with redox homeostasis in the testicular tissues of HFD-fed mice. This study found that PS-NPs could aggravate the damage to the reproductive system of obese male mice by further perturbing its redox homeostasis and revealed the potential health risk of PS-NPs exposure under an HFD.