Effect of Aging on Mitochondrial Physiological Parameters and Nitric Oxide Production in Synaptic and Non-synaptic Brain Cortex Mitochondria.

LORES-ARNAIZ, S.; COSTANZO, N.; BUSTAMANTE, J.

Santiago de Chile

Congreso; Free Radicals and Antioxidants in Chile, VI Meeting of the SFRBM South American Group; 2009

SFRBM South American Group

Mitochondria in nerve terminals are subjected to extensive calcium fluxes and high energy demands. Brain aging has been associated with mitochondrial dysfunction and changes in nitric oxide levels. The aim of this study was to evaluate the susceptibility of synaptic and non-synaptic mitochondria to aging-dependent dysfunction. Male Swiss mice of 3 or 14 months of age were used. Brain cortex synaptosomes and non-synaptic mitochondrial fractions were isolated by Ficoll gradient procedures. Mitochondrial physiological parameters and nitric oxide generation were measured in both subcellular fractions. State 3 respiratory rate and respiratory control were 43% and 33% decreased respectively in brain cortex synaptosomes from 14-months old animals, as compared with 3-months old mice, but were not affected by aging in non-synaptic mitochondrial fractions. Synaptosomes seem to be more susceptible to aging-associated depolarization, as compared with non-synaptic mitochondria. With aging, NO production was 44% and 27% decreased both in synaptosomal membranes and in non-synaptic mitochondrial fractions respectively. The results of this study suggest that with aging, mitochondria at the nerve terminals would be more susceptible to suffer alterations by the constant calcium changes occurring as a consequence of synaptic activity.