Age-dependent changes of NO synthase activity in the rat brain.
We report that NO synthase activity, as expressed by citrulline and nitrite formation in brain homogenates, is decreased in 24-month old in comparison to 3-month old rats. In particular, a Ca(++)-dependent NO synthase activity was detected in homogenates obtained from cortical, hippocampal, cerebellar and lower brain stem slices from both 3- and 24 month-old rats. The amount of citrulline generated from L-arginine was significantly decreased in the hippocampus and lower brain stem by 40 and 48%, respectively. No changes were observed in NO synthase activity in cortical and cerebellar homogenates. Thus, the L-arginine-NO pathway seems to be impaired in selected areas of rat brain and this may contribute to the understanding of pathophysiological mechanisms underlying age-related cerebral disorders.
D000375:Aging / Q000378:metabolism*; D000818:Animals; D001921:Brain / Q000201:enzymology* / Q000254:growth & development; D001933:Brain Stem / Q000201:enzymology; D002118:Calcium / Q000494:pharmacology; D002531:Cerebellum / Q000201:enzymology; D002956:Citrulline / Q000378:metabolism; D005625:Frontal Lobe / Q000201:enzymology; D006624:Hippocampus / Q000201:enzymology; D066298:In Vitro Techniques; D008297:Male; D019001:Nitric Oxide Synthase / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D009928:Organ Specificity; D010296:Parietal Lobe / Q000201:enzymology; D051381:Rats; D017208:Rats, Wistar
D009573:Nitrites; D002956:Citrulline; D019001:Nitric Oxide Synthase; D002118:Calcium