Effect of waterborne copper on lipid metabolism in hepatopancreas and muscle of grass carp Ctenopharyngodon idella

This study aims to determine the effect of waterborne copper (Cu) exposure on lipid metabolism in the hepatopancreas and muscle of grass carp Ctenopharyngodon idella. Grass carp was exposed to four levels of waterborne Cu (control, 0.058, 0.150 and 0.199 mg L-1) for 14 days. The lipid content, Cu accumulation, and the activities and expression levels of several enzymes involved in lipid metabolism were determined in hepatopancreas and muscle. Copper (Cu) accumulation was found in both tested tissues and the content increased with the increase in waterborne Cu concentrations. Waterborne Cu exposure reduced the lipid content and growth performance. In hepatopancreas and muscle, the activities and the mRNA expression of lipogenic enzymes (G6PD, 6PGD, ICDH, ME and FAS) decreased with the increase of waterborne Cu levels. Furthermore, the mRNA expression levels of lipolytic enzymes (HSL and ATGL) and transcription factors (SREBP-1 and PPARa) were downregulated by Cu exposure. The decrease of lipogenesis prevailed over that of lipolysis, which might lead the reduction in lipid contents. Taken together, this study demonstrates that waterborne Cu exposure can perturb the normal processes of lipid metabolism, which serves to improve our understanding of the mechanisms underlying lipid metabolism and deposition during Cu exposure in fish.