Procyanidin Protects Against Polystyrene Microplastic-Induced Male Reproductive Injury Through the NRF2/SLC7A11/GPX4 Pathway

Polystyrene microplastics (PS-MPs) are ubiquitous environmental contaminants of emerging concern owing to their potential adverse effects on male reproductive health. However, the mechanisms underlying PS-MP-induced reproductive injury remain poorly understood, and effective protective interventions are lacking. Here, we investigated the protective effects of procyanidin (PC), a naturally occurring polyphenolic antioxidant, against PS-MP-induced reproductive injury in mice and elucidated the underlying mechanisms using TM3 Leydig cells. In mice, PC treatment attenuated the PS-MP-induced reductions in serum testosterone levels, sperm concentration, survival, and motility. PC also reduced the incidence of sperm abnormalities and the severity of histopathological lesions in the testes and epididymis. PS-MP exposure increased testicular Fe2+ levels and lipid peroxidation while decreasing GSH levels and GSH-Px, CAT, and T-SOD activities; these changes were reversed by PC. PS-MP exposure also downregulated the expression of NRF2, SLC7A11, and GPX4 and altered the expression of ferroptosis-related markers; PC treatment largely reversed these changes. In TM3 cells, PC reduced PS-MP-induced Fe2+ accumulation and lipid peroxidation, preserved mitochondrial membrane potential, and attenuated mitochondrial permeability transition pore (MPTP) opening. These effects were weakened by Erastin, an inhibitor of system Xc− that suppresses SLC7A11-mediated cystine uptake, and by ML385, an NRF2 inhibitor, suggesting the involvement of ferroptosis-related and NRF2-mediated signaling. Molecular docking predicted potential interactions between PC and NRF2 and SLC7A11. Collectively, these findings indicate that PC protects against PS-MP-induced male reproductive injury, potentially by modulating the NRF2/SLC7A11/GPX4 pathway.