Comparative analysis of acute and chronic toxicological exposure effects of polystyrene nanoparticles on Macrobrachium rosenbergii: Implications for antioxidative defense and immunosuppression

Global pollution by microplastics (MPs) and nano-plastics (NPs) disrupts aquatic ecosystems and compromises the health of aquatic animals. However, there is a significant gap in the literature regarding acute high-dose and chronic low-dose polystyrene nano-plastic (PS-NP) exposures that simulate point-source and non-point source pollution events, respectively. The PS-NP concentrations (10 mg/L for acute exposure and 1 mg/L for chronic exposure) were designed to simulate realistic environmental scenarios. In this study, the giant freshwater prawn (Macrobrachium rosenbergii) was used as a model to investigate the differences on physiological functions under acute (96 h, 10 mg/L) and chronic (30 days, 1 mg/L) PS-NP exposure. Transcriptome sequencing and basic biochemical detection were utilized to analyze changes in gene expression, antioxidative and immunological responses of hepatopancreas. The results demonstrated that acute exposure to PS-NPs induced a significant upregulation of antioxidative and pro-inflammatory enzymes, suggesting a rapid stress response and activation of immediate defense mechanisms. In contrast, chronic exposure led to downregulation of mitochondrial and immune pathways, collapse of antioxidative defense, increased lipid peroxidation, and signs of immunosuppression. These findings underscored the time-dependent toxico-dynamics of PS-NPs and highlighted their potential ecological risks under prolonged exposure. The study provided molecular-level evidence to support more accurate environmental risk assessments and informs mitigation strategies for safeguarding aquaculture health in contaminated freshwater ecosystems.