Silymarin inhibits adipogenesis in the adipocytes in grass carp <Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis> in vitro and in vivo

In this study, two experiments were performed to explore the function of silymarin in adipogenesis in grass carp (Ctenopharyngodon idellus) using in vitro and in vivo models. In experiment 1, differentiated grass carp pre-adipocytes were treated with silymarin for 6 days. Treatment with 100 μg mL^?1silymarin (SM100 group) significantly reduced triglyceride accumulation at day 6. The adipogenic gene expression levels of PPARγ, C/EBPα, SREBP1c, FAS, SCD1, and LPL, and the protein expression level of PPARγ were significantly down-regulated in the SM100 group. Additionally, the SM100 group had significantly lower reactive oxygen species production and reduced glutathione contents compared with the control in vitro. In experiment 2, the juvenile grass carp (mean body weight= 27.4 ± 0.17 g) were fed six isonitrogenous and isocaloric diets in a factorial design containing 0, 100, or 200 mg kg^?1 silymarin (SM0, SM100, SM200) associated with either 4 or 8% lipid levels (low lipid, LL, and high lipid, HL, respectively) for 82 days. The results demonstrated that dietary silymarin supplementation significantly reduced the elevated intraperitoneal fat index in grass carp fed with high-lipid diets, and the gene expression of adipogenesis (PPARγ, FAS) when supplemented with dietary silymarin was notably lower than when no silymarin was supplemented under the high-lipid diets. Thus, our data suggest that silymarin suppressed lipid accumulation in grass carp both in vitro and in vivo, and the effect might be due to an influence on the expression of adipogenesis factors and ROS production partly associated with effects on antioxidant capability.