Effects of liquorice extract on the activity and gene expression level of antioxidant enzymes in longissimus dorsi muscle of Tan lamb

The objective of this study was to investigate the role of liquorice extract (LE) as a dietary antioxidant supplement in the regulation of muscle antioxidant enzyme in lambs. Fifty Tan male lambs were randomly allocated among five groups with LE supplementation at levels of 0, 1000, 2000, 3000 and 4000 mg/kg feed, respectively. After 120 days of feeding, the lambs were slaughtered and the longissimus dorsi muscle was sampled for measuring the antioxidant enzymes activities and genes expression levels. In addition, superoxide anion (02 hydrogen peroxide (H2O2) and thiobarbituric acid reactive substance (TBARS) levels were also tested in our study. The results showed that supplementation with LE increased (P < 0.05) glutathione peroxidase (GPx) and catalase (CAT) activities, but LE had no effect on Cu/Zn superoxide dismutase (Cu/Zn SOD) and Mn superoxide dismutase (Mn SOD) activities. For gene expression, no significant differences were observed in mRNA levels of Cu/Zn SOD, Mn SOD, GPx and CAT genes among the five groups. In addition, LE supplementation decreased (P < 0.05) O-2(-), H2O2 and TBARS levels in muscle. The results demonstrated that LE as a supplement could improve GPx and CAT activities, then prevent muscle against lipid oxidation.