Parthenolide Restores Testosterone Biosynthesis After Nanoplastic Exposure by Blocking ROS-Driven NF-κB Nuclear Translocation.

Nanoplastics are pervasive contaminants that adversely affect male reproductive function, yet the molecular basis of polystyrene nanoplastic (PS-NP) toxicity in immature testes and effective preventive strategies remain unclear. Here, male mice (postnatal days 22-35, PND 22-35) and TM3 Leydig cells were exposed to graded PS-NPs, followed by transcriptomic profiling to identify differentially expressed genes (DEGs). Candidate therapeutics were prioritized using Connectivity Map (CMap) analysis and molecular docking, and protein interactions were examined by co-immunoprecipitation (Co-IP). PS-NPs accumulated in immature testes, eliciting excessive reactive oxygen species (ROS) and activation of NF-κB. These events coincided with the downregulation of steroidogenic enzymes (CYP11A1 and StAR) and disruption of testicular microarchitecture. In TM3 cells, PS-NPs suppressed testosterone synthesis in a concentration-dependent manner; this effect was fully reversed by pretreatment with N-acetylcysteine (NAC) or Bay 11-7082. Co-IP demonstrated p65-steroidogenic factor-1 (SF-1) binding consistent with formation of a transcriptional repressor complex targeting steroidogenic genes. CMap and docking analyses nominated parthenolide (PTL) as a candidate inhibitor of NF-κB nuclear translocation (predicted binding affinity, -6.585 kcal/mol), and PTL mitigated PS-NP-induced impairment of testosterone synthesis in vitro. Collectively, these data indicate that PS-NPs disrupt testosterone biosynthesis in immature testes through the ROS/NF-κB/p65-SF-1 axis, while PTL emerges as a candidate small molecule to counter nanoplastic-associated reproductive toxicity. These findings underscore translational relevance and support future evaluation under chronic low-dose exposure conditions, including in vivo validation of PTL efficacy, pharmacokinetics, and safety.