FIGURE 5.

Prolonged exposure to insulin decreases mitochondrial mass, mtDNA, intracellular ATP level, and ATP synthase through Akt-dependent insulin signaling. Isolated mouse hepatocytes were pretreated with LY294002 for 30 min, and then treated with insulin in the continuous presence of LY294002 for 24 h. A, levels of phospho and total proteins of Akt were detected by immunoblotting. B, mitochondrial mass was evaluated. C, levels of mtDNA were quantified by real-time PCR and normalized as detailed under “Materials and Methods.” D, intracellular ATP content was measured as described under “Materials and Methods.” E, levels of ATP synthase protein were examined by immunoblotting. Results in B–D represent mean ± S.E. of three independent experiments. *, p < 0.05 versus all bars without asterisks in B–D.