Idebenone induces oxygen consumption rate modifications in aged rat brain mitochondria

Idebenone effects on oxygen consumption in brain mitochondria, obtained from young and aged rats, were evaluated. Sixty rats (3 and 20 months of age) were treated for 3 months with 30 mg/kg of idebenone and compared to a placebo group. Brain mitochondria oxygen consumption rate was measured by polarographic techniques in basal (State 4), ADP-stimulated (State 3) and uncoupled conditions. When Complex I substrates (pyruvate + malate) were used, aged non-treated rats showed a significant increase in State 4 (175%) and uncoupled (152%) O2-uptake rate; no difference was found in State 3 respiration and in ADP/O2 ratio. Idebenone was able to reverse these age-related effects probably acting on lipid peroxidation and the mitochondrial respiratory chain. No differences were found in mitochondrial enzymatic activities.