['Mitochondrial biogenesis includes both mitochondrial proliferation and differentiation and its regulation under different physiological conditions is not clear. Given the sexual dimorphism previously found in mitochondrial function, the aim of this study was to investigate the gender-dependent effect of chronic high-fat-diet (HFD) feeding on rat liver mitochondrial function and biogenesis.', 'Ten-week old male and female rats were fed a HFD (26% fat) or a control diet (2.9% fat) for 26 weeks. Mitochondrial morphology was studied. Mitochondrial DNA and protein content, hydrogen peroxide production, oxidative capacity, antioxidant defenses, as well as markers of oxidative damage and mitochondrial biogenesis were analyzed.', 'Female rats showed higher levels of mitochondrial protein and an enhanced oxidative capacity per mitochondrion than males. In both genders, HFD feeding increased mtDNA content and decreased mitochondrial differentiation markers.'] Does long-term high-fat-diet feeding impair mitochondrial biogenesis in liver of male and female rats?