Effects of polystyrene nanoplastic exposure on energy metabolism, lipid metabolism, and amino acid changes in Monopterus albus

Nanoplastics (NPs) have emerged as contaminants in recent years and have attracted widespread attention because of their ecotoxicological effects. This study aimed to document the effects of different concentrations of NPs on the Monopterus albus . M. albus . M. albus were orally administered three different concentrations of 100 nm polystyrene NPs (0.05%, 0.5%, and 1% of the feed) for 35 days. The effects of different NPs concentrations on energy metabolism, enzyme biomarker responses, gene expression responses, and amino acid changes were investigated in M. albus after exposure. The results revealed that the gene expression of phosphoenolpyruvate carboxykinase and glucose-6-phosphatase was up-regulated after the ingestion of high concentrations of NPs. The gluconeogenic pathway was inhibited, lactic acid (LA) content was increased, anaerobic glycolysis was used to produce LA to power the organism, and the accumulation of NPs led to a decrease in total cholesterol and triglyceride levels in liver tissues. There were increases in the relative liver content of glutamine, glycine, and methionine, which may be due to antioxidation in the liver. The stress may caused by NPs leads to the formation of some glutamylated amino acids, which are converted into glutathione to play an antioxidant role. NPs also induced lipotoxicity of the liver organoid by increasing lipid accumulation, these include methyl tetradecanoate (myristate), pentadecanoic acid, eicosanoic acid (arachidic acid), heptadecanoic acid (margaric acid), 5,8,11,14-eicosatetraenoic acid, and doconexent (Docosahexaenoic acid). Interestingly, some immune-related metabolites, such as 9-octadecenoic acid (oleic acid) and 9,12-octadecadienoic acid (linoleic acid), were significantly reduced, and these changes were probably caused by disturbances in hepatic lipid metabolism following NPs exposure.