AGE-RELATED MODIFICATIONS OF CYTOCHROME-C-OXIDASE ACTIVITY IN DISCRETE BRAIN-REGIONS

The apparent Km for cytochrome c cytochrome oxidase does not change but the Vmax decreases in synaptosomes and non-synaptic mitochonddria isolated from the cerebral cortex as a whole of 30-month-old rats compared with 4-month-old ones. When the subcellular organelles are submitted to stressfull conditions, namely incubation in media of altered osmolality, the percentage of cytochrome oxidase activity released is much higher in senescent rats. The activity of cytochrome oxidase evaluated in non-synaptic mitochondria and synaptosomes isolated from cortical and subcortical regions and cerebellum of rats aged 4 and 30 months shows a highly significant decrease (P < 0.001) in the parietotemporal cortex of senescent rats (both in non-synaptic mitochondria and synaptosomes) and in the cerebellum (in synaptosomes). © 1990.