Effects of α-lipoic acid (LA) supplementation in high-fat diet on the growth, glycolipid metabolism and liver health of largemouth bass (Micropterus salmoides)

An 8-week feeding trial was conducted to investigate the effects of LA supplementation in a high-fat diet on the growth performance, hepatic antioxidant capacity, and glycogen metabolism of largemouth bass (Micropterus salmoides). Five diets were formulated including control diet (11.55 % crude fat, CF), a high-fat diet (17.80 % crude fat, HF) and three HF diets supplemented with 0.15 %, 0.20 % and 0.25 % LA (HL0.15, HL0.20 and HL0.25, respectively). In this experiments, HL0.15 and HL0.20 could improve the uniform for the growth of the largemouth bass, while adding 0.25 % did not significantly improve growth. The highest viscerosomatic index (VSI) and hepatosomatic index (HSI) were measured in fish fed the HF diet. Compared to the fish fed HF diet, fish fed HL diets showed lower serum total triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), hepatic malondialdehyde (MDA) and glycogen levels, and higher hepatic catalase (CAT) and glutathione peroxidase (GSH-PX) activities. In addition, the mRNA expression for lipolysis genes in fish liver were increased and for gluconeogenesis and fatty acid synthesis were reduced. The transcript levels of apoptosis-related genes were significantly down-regulated in the liver of largemouth bass in HL0.15 and HL0.20 groups compared to the HF group. Moreover, compared with the HF group, the mRNA expression of pro-inflammatory factors was significantly reduced in HL groups, and the histomorphology of the liver were significantly improved. These results suggested that LA supplementation in high-fat diets could improve lipid utilization, glycogen accumulation, antioxidant capacity of fish liver, thus reduce the adverse effects of high fat diets on fish, and then improve the growth performance of largemouth bass.