Addition of berberine to formulated feed changes the glucose utilisation, intestinal microbiota and serum metabolites of Largemouth bass (Micropterus salmoides)

Largemouth bass (Micropterus salmoides) is extremely intolerant to carbohydrates in diets. To address this problem, this work studied the effects of berberine (BBR), a Chinese herbal extract with the serum glucoselowering activity in mammals, on regulating the serum glucose and intestinal microbiota in largemouth bass. The changes in glucose metabolism-related genes and serum metabolites were also determined to explore the possible pathways and underlying mechanisms. Our results showed that BBR reduced the serum contents of total cholesterol, triglyceride and glucose, and increased intestinal farnesoid X receptor (fxr) expression in largemouth bass (P < 0.001). BBR dramatically altered fxr downstream glycolysis- and gluconeogenesis-related genes, along with their enzyme activities (P < 0.001). Moreover, BBR changed the diversity of the intestinal microbiota, including decreasing the abundance of Fusobacteria and elevating those of Firmicutes and Proteobacteria (P < 0.001). Correlation analysis showed that the above increased bacteria in BBR group were strongly and positively related to the intestinal fxr genes. It was further found that the bacterial functions of Glycolysis/Gluconeogenesis, Nitrogen metabolism and Energy metabolism were enriched in the BBR group. Serum metabolomics analysis showed that BBR supplementation changed the metabolic processes, especially the metabolism of amino acids and carbohydrates. Correlation analysis found that, in the BBR group, the decreased abundance of Cetobacterium and increased abundances of Lachnospiracea and Ruminococcaceae were significantly correlated with the serum metabolites with serum glucose-lowering activity including butyrate, inosine, and N-methylhydantoin. Overall, these results confirmed that dietary supplementation of BBR decreased the serum glucose level of largemouth bass, possibly related to the changes of intestinal bacteria and their regulation on the intestinal-FXR signal pathways. Dietary BBR would provide new ways to improve the carbohydrate metabolism of largemouth bass.

Automated summary

This study found that berberine can lower blood glucose levels in largemouth bass by changing the intestinal microbiota and regulating the intestinal-FXR signal pathways. Berberine also has a regulatory effect on blood lipids in largemouth bass.