Dietary Methionine Hydroxy Analog Regulates Hepatic Lipid Metabolism via SIRT1/AMPK Signaling Pathways in Largemouth Bass Micropterus salmodies

This experiment was arranged to explore the impacts of dietary MHA on liver lipid metabolism in largemouth bass. A total of 480 fish (14.49 ± 0.13 g) were randomly allocated into four groups, each with three replicates. They were then given four different diets containing graded levels of MHA (0.0, 3.0, 6.0, and 9.0 g/kg) for 84 days. The results showed that dietary MHA increased hepatic lipid vacuoles and lipid content (<i>p</i> < 0.05). Dietary supplementation with MHA 9.0 g/kg diets increased the activities of acetyl-coA carboxylase (ACC), fatty acid synthase (FAS), and stearoyl-coA desaturase 1 (SCD-1). Dietary MHA up-regulated the mRNA expressions of liver lipid synthesis (ACC, FAS, SCD-1 and SREBP-1c) (<i>p</i> < 0.05). Furthermore, compared with the 0.0 g/kg diet group, the group supplemented with 9.0 g/kg MHA in the diet exhibited a significant decrease in the activities of liver lipid-oxidation-related enzymes (acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS), and stearoyl-CoA desaturase 1 (SCD-1), as well as HSL and CPT1) and the gene expressions of ATGL, HSLa, HSLb, CPT1a, and PPARα (<i>p</i> < 0.05). Additionally, the mRNA expressions and protein levels of SIRT1 and AMPK in the 9.0 g/kg MHA-supplemented group were significantly lower than those in the 0.0 g/kg diet group (<i>p</i> < 0.05). Overall, the present results suggested that dietary MHA could increase lipid accumulation through regulating SIRT1/AMPK signaling pathways in the livers of largemouth bass.