In Vitro Effects of Selenium on Copper-Induced Changes in Lipid Metabolism of Grass Carp (Ctenopharyngodon idellus) Hepatocytes

The present study was performed to evaluate the in vitro effects of selenium (Se) supplementation to prevent copper (Cu)-induced changes in lipid metabolism of hepatocytes from grass carp (Ctenopharyngodon idellus). Four groups (control and 100 mu M Cu in combination with 0, 5, and 10 mu M Se, respectively) were chosen. Compared with the control, activities of glucose 6-phosphatedehydrogenase, 6-phosphogluconate dehydrogenase, malic enzyme, and carnitine palmitoyltransferase I (CPT I) of all three Cu-exposed groups at 24 and 48 h were significantly greater. However, among three Cu-exposed groups, increasing Se concentration tended to increase activities of G6PD and ME at 24 h and 6PGD activity at 24 and 48 h but decreased CPT I activity at 24 h. Compared with the control, Cu exposure alone, or in combination with Se, downregulated mRNA levels of sterol regulatory element-binding protein-1 (SREBP-1c), fatty acid synthase (FAS), acetyl-CoA carboxylase, peroxisome proliferator activated receptor alpha (PPAR alpha), CPT I, and hormone-sensitive lipase (HSL) at 24 h as well as SREBP-1c, FAS, and ACC mRNA levels at 48 h. However, upregulated mRNA levels of PPAR alpha, CPT I, and HSL, as well as decreased triglyceride content, were recorded at 48 h. Thus, although toxic at greater levels, lower levels of Se provided significant protection against Cu-induced changes in lipid metabolism. For the first time, our study indicates the dose- and time-dependent effects of Se addition on changes in lipid metabolism induced by Cu in fish hepatocytes and provides new insights into Se-Cu interaction at both enzymatic and molecular levels.