Toxicology of aspartame to largemouth bass (Micropterus salmoides) on the basis of antioxidant capacity, liver histology and the intestinal microbiota

Aspartame is widely applied in the food industry as a sugar substitute, but concerns about its safety persist. There are a large number of studies on the toxicity of aspartame on mammals. The aim of this study was to assess the impacts of aspartame on the growth performance, biological indicators, liver histology, hepatic antioxidant capacity and to evaluate the potential of juvenile largemouth bass (Micropterus salmoides) as a model species for food toxicology. The results revealed that the feed intake of the ASBT group was significantly lower than that of the CT group. Compared with those in the CT group, the activities of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in the ASBT group were significantly greater ( P < 0.05), and the liver superoxide dismutase (SOD), total antioxidant capacity (T-AOC) and ccatalase (CAT) activities were significantly decreased (P < 0.05), suggesting abnormal liver functions and decreased hepatic antioxidant capacity respectively. Liver histology showed significantly increased hepatocytes volume and increased of intrahepatic fat cell area in the ASBT group than that in the CT group ( P < 0.05), indicating that the liver tissue was severely damaged. Compared with those in the CT group, the abundances of pathogenic bacteria such as Proteobacteria and Fusobacteria in the intestine of the ASBT group were significantly greater. It can be concluded that continuously feeding diets with 1 % aspartame has significant negative effects on largemouth bass, including liver damage, and increases the proportion of intestinal pathogens. The results are very similar to those described in mammalian disease models. Therefore, it is suggested that fish species like largemouth bass may be valuable for food toxicity studies.