Compared to mammals, fish exhibit poor carbohydrate utilization. Thus, exploring exogenous additives to promote efficient carbohydrate utilization in fish holds significant promise. In mammals, dietary supplementation with tea polysaccharides (TPS) has been associated with alleviating metabolic syndrome and inhibiting intestinal enzyme activities. However, limited research has focused on the effects of TPS on metabolic syndrome in fish. In this study, grass carp were fed three experimental diets (control; high-carbohydrate, HG; high-carbohydrate supplemented with 0.05% TPS, HG+TPS) for 8 weeks to investigate the effects of TPS supplementation on growth performance and carbohydrate utilization in fish fed a high-carbohydrate diet. Following the feeding trial, the HG+TPS group exhibited a significantly higher specific growth rate compared with the HG group. TPS supplementation inhibited exogenous glucose uptake in fish fed a high-carbohydrate diet by downregulating intestinal α-glucosidase activity and hepatic glut2 gene expression. In addition, TPS supplementation increased hepatic pk expression to stimulate glycolysis compared with the HG group. Furthermore, the hepatic glycogen content of fish fed the HG+TPS diet was increased by decreasing the pygl gene expression compared to fish fed with the HG diet. Therefore, TPS supplementation alleviated glucose stress induced by high carbohydrate intake by inhibiting intestinal glucose absorption, enhancing hepatic glycogen accumulation, and promoting the glycolysis process. These results provide evidence of the potential application of TPS as an antihyperglycemic additive in aquatic feeds.
Wang et al. (Tue,) studied this question.