Fig. 5.

ROS production induced by the prolonged exposure to insulin is cholesterol synthesis dependent in hepatocytes. Hepa1c1c7 cells (A) or primary mouse hepatocytes (B) were treated with either the vehicle solution or insulin (5 nm) in the presence or absence of simvastatin (10 nm) for 16 h as indicated (n = 3). Cells were incubated with carboxy-H2-DCF-DA for 30 min, followed by quantification of ROS level. C, Levels of HMG-CoA-R activity in the cells described in A were quantified by using an HMG-CoA-R assay kit as detailed in Materials and Methods. Results represent mean ± se of three independent experiments. **, P < 0.01 vs. no insulin; #, P < 0.05 and ##, P < 0.01 vs. insulin alone.