AGE-ASSOCIATED CHANGES OF MITOCHONDRIAL TRANSLATION AND RESPIRATORY-FUNCTION IN MOUSE-BRAIN

We examined age-associated changes of respiratory enzyme activities an d protein synthesis in mitochondria isolated from mouse brain with hig h oxidative activities. Cytochrome c oxidase activity increased unexpe ctedly with aging, while the mitochondrial translational activities sh owed two phases of alterations: they increased progressively up to 21 weeks after birth followed by a gradual decrease with aging. Results s howed that these changes were not due to the change in mitochondrial D NA (mtDNA) copy number or the accumulation of deletion mutations in mt DNA. These observations suggest that the common feature of age-associa ted changes in both human and mouse mitochondrial functions is limited to the decrease in mitochondrial translational activity. Therefore, m ouse brain can be used as a model to understand the relationships betw een aging and mitochondrial function by examining the cause of decreas e in mitochondrial translation activity. (C) 1995 Academic Press, Inc.