Simvastatin Improves the High-Fat-Diet-Induced Metabolic Disorder in Juvenile Chinese Giant Salamander (Andrias davidianus) Through Inhibiting Endoplasmic Reticulum Stress and Enhancing Mitochondrial Function

In order to deeply understand the potential mechanisms underlying the metabolic disorders of Chinese giant salamander (Andrias davidianus), a total of two feeding trials were conducted in the present study. For experiment I, the diets containing five graded levels of lipids at 32.8, 58.7, 87.9, 122.4, and 149.2 g/kg were formulated, respectively, and fed to juvenile A. davidianus for 90 days. The quadratic regression analysis based on growth performance results indicated that the optimal dietary lipid level is 95.16–101.02 g/kg. Meanwhile, a dietary lipid level of 149.2 g/kg was found to reduce the growth performance of A. davidianus. Based on this, in experiment II, a normal-fat diet (86.8 g/kg crude lipid), a high-fat diet (HFD, 148.4 g/kg crude lipid), and an HFD supplemented with 0.1 g/kg simvastatin were prepared, respectively, and fed to the juveniles for 90 days. The results indicated that HFD feeding resulted in hyperlipidemia, hepatic damage, endoplasmic reticulum stress, and mitochondrial dysfunction, while simvastatin administration alleviated these symptoms. In conclusion, simvastatin could alleviate the HFD-induced metabolic disorders in A. davidianus, as may be achieved by inhibiting ER stress and enhancing mitochondrial function.