Background: The widespread presence of nanoplastics in the environment has raised concerns regarding their potential effects on early-life development. However, information on the neurodevelopmental consequences of lactational exposure to polystyrene nanoplastics (PSNPs) remains limited.
Objectives: The present study investigated the effects of maternal PSNP exposure during lactation on the hippocampus and cerebellum of male rat offspring.
Methods: Pregnant Sprague–Dawley rats were orally administered PSNPs at doses of 0.1, 1, or 10 mg/kg/day during the 21-day lactation period. Male offspring were evaluated on postnatal days (PD30 and PD60). Brain growth indices, histomorphometric parameters, oxidative stress markers, and immunohistochemical (IHC) expression of p53, BCL-2, GFAP, and Olig-2 were also assessed.
Results: PSNP exposure was associated with reduced body and brain weights at PD30, whereas a persistent decrease in brain weight was observed only in the high-dose group at PD60. Histomorphometric analysis revealed a reduction in CA1 neuronal density and thinning of the hippocampal and cerebellar layers, particularly in the medium- and high-dose groups. IHC evaluation demonstrated increased p53 and GFAP expression and decreased BCL-2 and Olig-2 expression in both brain regions. At PD30, the exposed animals exhibited a dose-dependent reduction in total antioxidant capacity (TAC), along with a dose-dependent increases in total oxidant status (TOS) and oxidative stress index (OSI), compared with the control group, indicating an oxidative imbalance. These biochemical alterations were no longer significant at PD60, although several structural and cellular changes remained.
Conclusion: Collectively, these findings suggest that maternal PSNP exposure during lactation may be associated with alterations in postnatal brain development and is associated with alterations in brain morphology, oxidative status, apoptosis-related signaling, and glial markers in male rat offspring. Further studies are required to determine the long-term functional implications of these changes in the brain.