Skeletal muscle PGC-1, TFAM, COXII, COXIV, CPT1 proteins and mitochondrial DNA levels. Levels of mtDNA are expressed as AU (arbitrary units). Protein levels are expressed as % AU, where control male rats were set as 100%. Values are expressed as the mean ± S.E.M of eight animals per group. ANOVA (p < 0.05): S sex effect, D HFD effect, S*D sex and HFD interactive effect and NS non significant effect. Student's t-test (p < 0.05): a HFD vs control, b female vs male.