Mitochondrial nitric oxide synthase and O2 reactive species in ageing.

CONVERSO D; LEVISMAN D; CARRERAS MC; PODEROSO JJ

Buenos Aires

Congreso; XII Biennial Meeting of the Society for Free Radical Research International; 2004

Society for Free Radical Research International

In ageing, it had been reported mitochondria alteration consecutive to an increase in oxygen active species production. Considering that nitric oxide (NO) increases the mitochondrial production of oxyradicals, changes in NOS expression and activity could explain common findings in senescence and neurodegeneration. The purpose of the present study was to examine the role of mitochondrial nitric oxide synthase (mtNOS) during the ageing process. We studied mitochondria from rat tissues at different ages (0-24 mo.) and analyzed antioxidant enzymes activity, mitochondrial complex activities and mitochondrial production of NO and hydrogen peroxide (H2O2). We found 100% increase of mtNOS activity of liver (3 mo.:23± 2, 18 mo.: 41±1, 24 mo.: 45±2) and brain ( 3 mo.:18± 2, 18 mo.: 28±0.5, 24 mo.: 36±2) male or female of old rats (18-24 mo.); mitochondrial H2O2  significantly increased at 12-18 mo. but decreased at 24 mo.. At this age, activity of respiratory complex I-III was decreased whereas no significant alteration was observed in complexes II-III and IV. Superoxide dismutase activity significantly increased at 12 mo. and decreased at 18 and 24 mo. The data suggest that increase basal mtNOS and O2 active species and a decrease of antioxidant capacity contribute significantly to age-related decline of mitochondrial functions.