Developmental effects of intrauterine and lactational exposure to nanoplastics and phthalates on rat testis

The toxicity of nanoplastics (NPs) and plastic additives such as phthalates, recognized endocrine-disrupting chemicals, remains insufficiently understood, particularly regarding their combined effects on male reproductive health across the lifespan. Since these contaminants can cross biological barriers, including the placenta, this study, grounded in the developmental origins of health and disease (DOHaD) concept, evaluated the effects of gestational and lactational exposure to NPs and a phthalate mixture (PM) on testicular development and function in male offspring. Pregnant SD rats were allocated to six groups: control (CTRL); T1 (20 μg/kg/day PM); T2 (200 mg/kg/day PM); T3 (NPs: 1 mg/kg/day,100 nm); T4 (20 μg/kg/day PM + NPs); and T5 (200 mg/kg/day PM + NPs). Animals were exposed orally from gestational day 10 to postnatal day (PND)21. Male offspring were euthanized at PND22 (prepuberty) and PND120 (adulthood). At PND22, increased apoptosis in pachytene spermatocytes was observed in the T5 group compared with the CTRL, along with altered gene expression, including increased Amh (T4 vs.T1) and Srd5a1 (T1-T4 vs.CTRL) and reduced Ar expression (T3 vs.CTRL). At PND120, the exposure decreased seminiferous tubule diameter (T2), epithelial height (T1-T5), and numbers of Sertoli (T2-T5) and Leydig cells (T4 and T5) compared to the CTRL. Histopathological alterations were more incident in the T1, T3, T4, and T5 compared to the CTRL, and reduced Tjp1 expression in co-exposed animals suggested impairment of the blood-testis barrier. Redox analyses revealed age-dependent worsening of oxidative stress, particularly in co-exposure groups. Overall, gestational co-exposure to phthalates and NPs disrupts testicular morphology, gene regulation, and redox balance, indicating synergistic and persistent reproductive toxicity.