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Sex-specific reproductive toxicity of polystyrene nanoplastics and DEHP in adult zebrafish (Danio rerio)
Summary
Researchers studied how polystyrene nanoplastics and the plasticizer DEHP affect reproduction in male and female zebrafish when exposure occurs individually or together. They found that combined exposure caused gonadal tissue damage and oxidative stress in both sexes, but with strikingly different hormonal responses between males and females. The study suggests that nanoplastics and plastic additives disrupt reproductive endocrine function in sex-specific ways through the hormonal signaling axis.
Micro- and nanoplastics (MNPs) and di(2-ethylhexyl) phthalate (DEHP) are ubiquitous environmental contaminants; however, the risks of their combined exposure to aquatic reproductive health, particularly sex-specific differences, remain incompletely understood. This study investigated the effects of single and combined exposure to polystyrene nanoplastics (PS-NPs; 0.1 and 1 mg/L) and DEHP (10 μg/L) on the reproductive endocrine system of adult male and female zebrafish (Danio rerio) Results demonstrated that PS-NPs accumulated in the zebrafish intestine. High concentrations of PS-NP and DEHP and their combined exposures induced significant adverse effects in both sexes, including gonadal tissue damage and oxidative stress. A striking sexual dimorphism was observed in endocrine responses. Females exhibited a pronounced suppression of both 17β-estradiol (E2) and testosterone (T) levels, which correlated with inhibited ovarian cyp19a gene expression under co-exposure. Conversely, male E2 levels remained stable and T levels decreased only under co-exposure, increasing E2/T ratio. This distinct male endocrine profile was associated with differential regulation of testicular cyp19a and 17β-hsd expression. This study confirms that PS-NPs and DEHP exert profound sex-specific reproductive toxicity in zebrafish. These effects are mediated by disrupting the hypothalamic-pituitary-gonadal (HPG) axis, while inducing sex-specific alterations in brain and gonadal gene expression. Overall, this study highlights the critical importance of considering sex differences and pollutant mixture effects in environmental risk assessments.