Fragile X syndrome is the most common form of inherited mental retardation in humans. It originates from the loss of expression ofthe Fragile X mental retardation 1 (FMR1) gene, which results in the absence of the Fragile X mental retardation protein. However,the biochemical mechanisms involved in the pathological phenotype are mostly unknown. The availability of the FMR1-knockoutmouse model offers an excellent model system in which to study the biochemical alterations related to brain abnormalities in thesyndrome. We show for the first time that brains from Fmr1-knockout mice, a validated model for the syndrome, display higher levelsof reactive oxygen species, nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase activation, lipid peroxidation and proteinoxidation than brains from wild-type mice. Furthermore, the antioxidant system is deficient in Fmr1-knockout mice, as shown byaltered levels of components of the glutathione system. FMR1-knockout mice lacking Fragile X mental retardation protein werecompared with congenic FVB129 wild-type controls. Our results support the hypothesis that the lack of Fragile X mental retardationprotein function leads to a moderate increase of the oxidative stress status in the brain that may contribute to the pathophysiology ofthe Fragile X syndrome.
