Dual regulation of bile acids: ameliorating hepatic glycolipid disorders and restoring intestinal health in HFHC-challenged Yellow River carp (Cyprinus carpio L.)

Background This study was designed to investigate how three distinct bile acids (BAs) modulate glycolipid metabolic disorders and hepatointestinal injury induced by excessive intake of lipids and carbohydrates in Yellow River carp ( Cyprinus carpio L.) and elucidate the underlying mechanisms involved. Here, the fish were randomly assigned to five groups: a control group (CON), a high-fat high-carbohydrate diet (HFHC) group, a HFHC + 300 mg/kg chenodeoxycholic acid (CDCA) group, a HFHC + 300 mg/kg ursodeoxycholic acid (UDCA) group and a HFHC + 300 mg/kg hyodeoxycholic acid (HDCA) group. Results The results revealed that the serum triglyceride, glucose, and total cholesterol levels were significantly elevated in HFHC-fed fish, accompanied by increased glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) activities in the serum and hepatopancreas. However, dietary supplementation with bile acids in the HFHC diet significantly improved these negative changes. Analysis of BA-glycolipid metabolism-related gene expression and enzyme activities in the hepatopancreas revealed that CDCA and HDCA inhibited gluconeogenesis (FBPase/PEPCK/G6Pase) and lipogenesis (SREBP-1/FAS), while promoting glycogen accumulation (genes and glycogen levels) and fatty acid β-oxidation (PPARα) via activation of the FXR (farnesoid X receptor) /SHP (small heterodimer partner) pathway. In contrast, dietary UDCA supplementation increased intestinal TGR5 (takeda G protein-coupled receptor 5) expression and suppressed the activities of two key gluconeogenic enzymes, PEPCK and G6Pase. Additionally, dietary BAs supplementation alleviated HFHC diet-induced intestinal inflammation by inhibiting the NF-κB (Nuclear Factor κB) pathway. Bile acids relieved gut dysbiosis, improved microbial alpha diversity and community structure, and enriched beneficial bacteria including Cetobacterium somerae . These microbial changes eventually modulated host substance synthesis and metabolism. HE staining showed that HFHC diet caused hepatopancreatic lesions and intestinal morphological damage in Yellow River carp, which were effectively alleviated by bile acid addition. Conclusions In conclusion, HFHC diets disrupt fish glycolipid metabolism and impair hepato-intestinal health in Yellow River carp, whereas dietary BAs can attenuate these detrimental effects by modulating metabolic pathways and the gut microbiota composition. Graphical