Effects of dietary glutathione on growth performance, muscle quality and lipid metabolism of hybrid crucian carp (Carassius auratus cuvieri ♀ × Carassius auratus red var. ♂) fed a high-fat diet

A 60-day feeding trial was conducted to investigate the influence of glutathione (GSH) on growth performance, lipid metabolism and muscle quality of hybrid crucian carp (initial body weight: 15.03 ± 0.11 g) fed a high-fat diet (HFD). Five experimental diets were prepared in this study: the control diet (6.17% fat), HFD (12.37% fat), and HFD with 200 mg/kg, 400 mg/kg and 600 mg/kg GSH supplementation, respectively. The results indicated that feeding HFD to hybrid crucian carp remarkably reduced weight gain rate (WGR), specific growth rate (SGR), total antioxidant capacity (T-AOC) and total superoxide dismutase (T-SOD) activities of serum and liver, glutathione peroxidase (GSH-Px) and glutathione reductase (GR) activities of liver, but significantly increased malondialdehyde (MDA) content of liver compared to the control group. After adding 200–600 mg/kg GSH to HFD, the WGR, SGR, as well as serum and liver T-AOC activity of hybrid crucian carp increased significantly. Moreover, the supplementation of 400 mg/kg GSH significantly increased the activities of T-SOD, catalase (CAT) of serum and liver, as well as the GSH-Px, glutathione-S-transferase (GST) and GR of liver, but decreased MDA content of serum and liver compared to the HFD. The HFD significantly increased muscle crude lipid, polyunsaturated fatty acids (PUFA) contents and fiber diameter, but decreased chewiness, gumminess, hardness and fiber density compared to the control group. The addition of 400–600 mg/kg GSH significantly increased muscle chewiness, gumminess, hardness, and decreased muscle fiber diameter of HFD-fed hybrid crucian carp. Meanwhile, the addition of 200–600 mg/kg GSH significantly reduced the mono-unsaturated fatty acids (MUFA) content and increased the PUFA content of muscle compared to the HFD. The HFD significantly up-regulated the expression of lipid synthesis genes (dgat2 and srebp1) and down-regulated the expression of lipolysis genes (lpl, hsl and acox1) of liver compared to the control group. The addition of 400–600 mg/kg GSH significantly decreased the expression of lipid synthesis genes (dgat2 and srebp1) and increased the expression of lipolysis genes (hsl, lpl, acox1 and pparα) of HFD-fed hybrid crucian carp. This study demonstrated that GSH effectively ameliorated the decline of growth performance and muscle quality of hybrid crucian carp caused by HFD, and reduced the risk of liver lipid deposition of hybrid crucian carp by regulating the expression of genes related to liver lipid metabolism.