Age-dependent variations in mitochondrial and cytosolic antioxidant enzymes and lipid peroxidation in different regions of central nervous system of guinea pigs.

The age-related changes in the activities of antioxidant enzymes of mitochondrial and cytosolic fractions were measured in different regions of the central nervous system (CNS) in 10 and 32 months old guinea pigs. In old animals, the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPx) were reduced (p < 0.05) in all the regions of CNS studied but catalase (CAT) declined significantly only in the cerebral cortex, hypothalamus and cerebellum. Glutathione reductase (GRd) activity declined in cerebral cortex and hypothalamus in the cytosolic fractions and only in cerebellum in the mitochondrial fraction. It is concluded that age-related decline in the activities of antioxidant enzymes is both region and enzyme specific. The endogenous lipid peroxide was found to be significantly higher (p < 0.05) in the 32 month old animals whereas, lipid peroxidation after incubating the tissue homogenate in air was found to be lower (p < 0.05). The in vitro mitochondrial lipid peroxidation decreased with age. The results indicate that accumulation of lipid peroxides takes place with ageing but the susceptibility of lipid peroxidation decreases in the older animals.