Dietary trehalose reduced liver glycogen accumulation and promoted protein deposition in hybrid grouper (Epinephelus fuscoguttatus ♀ × E. lanceolatus ♂) fed a high-carbohydrate diet

The present study investigated the primary factors contributing to liver dysfunction induced by high-carbohydrate diets and assessed the potential of trehalose in mitigating these effects in hybrid grouper ( Epinephelus fuscoguttatus♀ × E. lanceolatus♂ ). During an eight-week feeding trial, hybrid grouper were fed either a control diet or a high-carbohydrate (HC) diet supplemented with trehalose at concentrations of 0 %, 1.5 %, and 3 %. Body weight was significantly lower in fish fed HC alone compared to fish fed the control diet, but was increased significantly by supplementing the HC diet with 3 % trehalose. While liver total lipid and triglyceride contents, and mesenteric fat index were not increased in fish fed HC alone compared to fish fed the control diet, addition of 3 % trehalose to the HC diet significantly increased these parameters. Although trehalose supplementation increased peroxisome proliferator-activated receptor α ( pparα) gene expression in liver, it significantly inhibited hepatic lipolysis in fish fed HC alone. Blood glucose and liver glycogen levels were significantly higher in grouper fed HC alone compared to the control group, and the supplementation of HC with trehalose (1.5 % and 3 %) further elevated blood glucose levels, but markedly reduced liver glycogen content. Liver expression levels of insulin receptor ( ir ), glucose transporter 2 ( glut2 ), glycogen synthase ( gs ) and glucokinase ( gk ) were increased significantly in grouper fed HC alone compared to fish fed the control diet and addition of 3 % trehalose reduced these levels, other than glut2 . Supplementation of 3 % trehalose to HC also reduced liver expression of pyruvate kinase ( pk ) and glucose-6-phosphatase ( g6pase ), but increased significantly the expression of glycogen phosphorylase ( gp ), while the expression of these genes was not different between fish fed HC alone and control diets. Serum alanine aminotransferase and aspartate aminotransferase activities were elevated significantly in fish fed HC alone compared to control diet, and decreased significantly by supplementation with 3 % trehalose. Additionally, liver malondialdehyde levels were increased in fish fed HC alone compared to control diet, but reduced significantly in fish fed HC supplemented with 3 % trehalose. While crude protein contents of liver and muscle were not impacted significantly by HC alone compared to the control diet, they were increased significantly by trehalose supplementation, with liver expression levels of mTORC1 and S6 proteins enhanced significantly by 3 % trehalose. Moreover, microbiota analysis showed increased abundance of Cetobacterium in the intestine of grouper fed the trehalose-supplemented diets. In summary, the results indicated that HC led to glycogen rather than lipid accumulation in liver, while trehalose treatment mitigated HC-induced glycogen accumulation by inhibiting glycogenesis and promoting glycogenolysis . Therefore, the present study revealed glycogen accumulation may be a key factor in high carbohydrate diet-induced liver health issues in grouper, and suggested trehalose as a potential intervention to mitigate negative impacts of high dietary carbohydrate on growth and liver health. • High carbohydrate (HC) intake led to liver glycogen rather than lipid accumulation in hybrid grouper. • Trehalose mitigated HC-induced glycogen accumulation by inhibiting glycogenesis and promoting glycogenolysis . • Trehalose enhanced protein synthesis may be associated with increased abundance of Cetobacterium in the intestine. • Trehalose has the potential to mitigate negative impacts of HC on growth and liver health.