Hydroxyl radical generation and nitric oxide synthase activity in Fisher 344 x brown-Norway F1 rat brain.

Hydroxyl radical production in the cerebral cortex, striatum and hippocampus of young (6 months), middle-aged (15 months) and old (28 months) Fisher 344 x Brown-Norway F1 rats was quantitated by measuring the salicylate hydroxyl radical-trapping product, 2,5-dihydroxybenzoic acid. The levels of hydroxyl radical between different age groups in each region examined were not statistically different. In all regions, with the exception of hippocampus from old rats which had a lower content of hydroxyl radical, the levels of hydroxyl radical were higher for middle-aged and old rats than young ones. There was no regional difference in the production of hydroxyl radicals, except that the level was significantly higher in striatum than in cortex for 15-month-old rats. The cerebral cortical nitric oxide synthase activities were similar in the three age groups studied.