Dietary Fenofibrate Reduces Hepatic Lipid Deposition by Regulating Lipid Metabolism in Yellow Catfish Pelteobagrus fulvidraco Exposed to Waterborne Zn

Fenofibrate is known to possess lipid-lowering effects by regulation of gene transcription involved in lipid metabolism. Waterborne Zn exposure induces lipid deposition in yellow catfish Pelteobagrus fulvidraco. Thus, the present working hypothesis is that dietary fenofibrate addition will reduce hepatic lipids in yellow catfish exposed to waterborne Zn. To this end, juvenile yellow catfish were exposed to 0.04 (control), 0.35 mg/L waterborne Zn, 0.15 % dietary fenofibrate, and 0.35 mg Zn/l + 0.15 % dietary fenofibrate for 8 weeks. Growth performance, lipid deposition and metabolism in the liver were determined. Dietary fenofibrate promoted growth performance and reduced hepatic lipid content of yellow catfish exposed to waterborne Zn. However, these effects did not appear in fish in normal water. The lipid-lowering effect of fenofibrate on fish exposed to waterborne Zn was associated with increased lipolysis, as indicated by increased CPT I activities and expression of lipolytic genes PPAR alpha, CPT IA, ATGL and HSL, and with reduced lipogenesis as indicated by reduced activities of G6PD, 6PGD, ME and ICDH. Dietary fenofibrate significantly increased mRNA levels of FAS, LPL and ACC alpha, but reduced mRNA levels of ACC beta and PPAR gamma in fish exposed to waterborne Zn. Pearson correlations between transcriptional factors expression, and activities and expression of several enzymes were observed, indicating that changes at the molecular and enzymatic levels may underlie the patterns of lipid metabolism and accordingly affect hepatic fat storage. Taken together, our results suggest that the lipid-lowering effect of fenofibrate was attributed, in part, to the down-regulation of lipogenesis and up-regulation of fatty acid oxidation.