Impact of polystyrene microplastic exposure at low doses on male fertility: an experimental study in rats.

Polystyrene microplastics (PS-MPs), widely used in commercial and pharmaceutical products, are emerging endocrine-disrupting pollutants with potential reproductive toxicity. This study evaluated the dose-dependent effects of PS-MPs on adult male rats by assessing semen quality, reproductive hormones, oxidative stress, mitochondrial and inflammatory markers, and testicular histology. Rats were assigned to six groups: a control group and five groups receiving PS-MPs orally (0.1, 1, 10, 20, or 40 µg/kg BW) for 45 days. PS-MP exposure reduced sperm count and motility, increased abnormal sperm, decreased testosterone, and elevated FSH and LH. Mitochondrial biogenesis/function markers (PGC-1α, UCP1, TFAM) were downregulated, while NF-κB, caspase-3, and TBARS were increased, accompanied by significant depletion of antioxidant defenses (GSH, GR, GPx, SOD, GST, CAT, TAC) and pronounced testicular histopathology. These effects were dose-dependent, and PS-MPs were detected in testicular tissue by pyrolysis-GC/MS at the doses of 10 µg/kg and higher. Collectively, the data identify mitochondrial dysfunction-driven oxidative stress and associated inflammation as a key mechanism by which PS-MPs induce spermatogenic failure, hormonal disruption, and testicular damage, highlighting their potential as potent male reproductive toxicants.