Brain Cortex Nitric Oxide Synthase and Mitochondrial Function During Rat Growth.

BUSTAMANTE, J.; LORES ARNAIZ, S.; KOROTKOV, D.; GARCIA ROSOLEN, N.; BOVERIS A.

Buenos Aires, Argentina

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

Society for Free Radical Research International

Mitochondria were isolated from 1, 3, 7 and 14 months old rats, oxygen uptake and mitochondrial nitric oxide synthase (mtNOS) activity were compared. Western blot followed by Northern blot analysis were conducted to analyze protein and mRNA expression. Succinate-dependent state 3 respiration rates were 34% and 78% higher in 7 and 14 months rats respectively as compared with 1 month old rats. Slight increase was observed in state 4 respiration rates, but no significant differences were found between the different ages. Malate-glutamate supported state 3 respiration rates were 39% and 85% higher in 7 and 14 months rats respectively compared with 1 month old rats. mtNOS measured as NO production was 0.80 ± 0.01  nmol/min.mg protein in 1 month rats, decreasing by 19%, 40% and 71% in 3, 7, and 14 months rats respectively. Western blot analysis of NOS mitochondrial fractions indicated that it reacts against nNOS antibodies (amino and carboxy terminus), and that the expression was higher in 1 month than in 14 months old rats. Northern blot indicated that nNOS brain mRNA levels increased in 1 month as compared with 14 months old rats.  Interestingly eNOS brain cortex mRNA levels were higher in the older animals, while iNOS brain cortex mRNA levels were minimal. Our results indicate  that during rat growth (from 1 to 14 months) the activity and expression of brain cortex mtNOS decreases associated with an increase in mitochondrial respiration.