Lactational exposure to polystyrene nanoplastics induces oxidative stress, testicular histological alterations, and impaired sperm quality in rat offspring.

The widespread presence of nanoplastics in the environment has raised concerns regarding their potential adverse effects on reproductive health, particularly during the early developmental stages. Among these contaminants, polystyrene nanoplastics (PSNPs) can cross biological barriers and accumulate in tissues; however, the reproductive consequences of lactational exposure remain insufficiently understood. This study investigated the effects of maternal exposure to PSNPs during lactation on testicular development, oxidative stress, spermatogenesis, and sperm quality in male rat offspring on postnatal days (PD) 30 and 60. Lactating Sprague Dawley rats were orally administered PSNPs at doses of 0.1, 1, or 10 mg/kg/day from postnatal days 1 to 21. Male offspring were evaluated on PD30 and PD60. Testicular morphometry, histopathological alterations, oxidative stress biomarkers, reproductive hormone levels, sperm characteristics, and immunohistochemical expression of p53 and BCL-2 were also assessed. Histopathological examination revealed degeneration of seminiferous tubules, reduction in germinal epithelium height, and impaired spermatogenic organization, particularly at higher exposure doses. Significant alterations in oxidative stress biomarkers were observed, characterized by an increased total oxidant status and oxidative stress index, accompanied by a reduced antioxidant capacity. Sperm analysis revealed reductions in sperm count, motility, and viability, along with increased morphological abnormalities in the exposed groups. Hormonal evaluation indicated disturbances in serum testosterone, luteinizing hormone, and follicle-stimulating hormone (FSH) levels. Immunohistochemical analyses further demonstrated increased p53 expression and reduced BCL-2 immunoreactivity, suggesting the activation of apoptosis-related pathways. Lactational exposure to PSNPs adversely affects testicular development and sperm quality in male offspring, potentially through oxidative stress and apoptosis-related mechanisms. These findings suggest that early life exposure to nanoplastics during critical developmental periods may contribute to reproductive dysfunction, highlighting the need for further investigation into the long-term biological effects of environmental nanoplastic exposure.