Effects of nanopolystyrene and/or phoxim exposure on digestive function of Eriocheir sinensis

Nanopolystyrene (NP) and phoxim (PHO) are pervasive environmental contaminants that pose a significant threat to the health of aquatic organisms, prompting widespread concern among researchers and the public alike. The hepatopancreas play important roles in the Chinese mitten crab (Eriocheir sinensis), such as digestion, absorption and detoxification. This study assessed the hepatopancreatic toxicity caused by the exposure of Eriocheir sinensis to environmentally relevant concentrations of NP and/or PHO. After a 21-day exposure period, NP (1.0 × 10¹⁰ particles/L) and PHO (24 μg/L) exposure resulted in reduced number of blister-like, resorptive, and fibrillar cells and an elevation in lipid droplets within the hepatopancreas compared to the control group. Furthermore, trypsin and lipase activity decreased, amylase activity increased, and a significantly decrease in the expression of digestion-related genes, including CHT, CarL, and CarB, suggested impairment in both digestive and metabolic functions. The marked upregulation of key genes, including PPARγ, GYK, PEPCK, and SCD, as well as key metabolites such as 4-methylzymosterol-carboxylate, zymosterone, lathosterol, 7-dehydro-desmosterol, vitamin D2, 24-methylene-cycloartanol, 5-dehydroepisterol, and sitosterol in the lipid metabolic pathway, showed that the peroxisome proliferator-activated receptor (PPAR) and steroid biosynthesis signaling pathways were highly affected by exposure to NP and/or PHO. These findings indicated that exposure to NP and/or PHO might adversely affect the hepatopancreatic physiological homeostasis in E. sinensis by causing tissue damage and interfering with digestive and metabolic functions. Our results provide ecotoxicological insights into the effects of nanopolystyrene and/or phoxim exposure on the digestive function of Eriocheir sinensis.