Age-related changes in the distribution of nitrotyrosine in the cerebral cortex and hippocampus of rats.

A wealth of indirect evidence implicates oxidative damage of cellular constituents in aging, as well as in the pathogenesis of the neurodegenerative diseases of later years. In the present study, we have determined age-related changes in the distribution of 3-nitrotyrosine (3-NT) in the cerebral cortex and hippocampus of rats. In adult rats, no 3-NT-immunoreactive cells were found in the cerebral cortex and hippocampus, whereas 3-NT immunoreactivity was significantly increased in aged rats. Some pyramidal cells of CA3 area and granule cells of the dentate gyrus highly expressed 3-NT in aged rats. Many interneurons located within stratum pyramidale and stratum oriens of CA1 were strongly immunoreactive for 3-NT. Our first demonstrations of increased 3-NT in the cerebral cortex and hippocampus during aging implicate these areas as sites for functionally significant oxidative damage. The mechanisms underlying the increased immunoreactivity for 3-NT, and the functional implications of this increase, require elucidation.