Post-lesion overexpression of Cu/Zn SOD decreases nitrotyrosine immunoreactivity. Sections from the caudal region of the CA1 hippocampal layer (bregma -2.43) of the contralateral side showed a basal nitrotyrosine immunoreactivity (A, Or: stratum oriens; Py; stratum pyramidalis; Ra: stratum radiatum). After NMDA injection, an increased immunorectivity was detected (B). However, animals overexpressing Cu/Zn SOD showed reduction in nitrotyrosine immunoreactivity (C), while animals overexpressing GFP showed a less pronounced reduction (D). Quantitative analysis confirmed these observations whereby, only animals overexpressing Cu/Zn SOD showed a significant (p < 0.05) decrease in nitrotyrosine immunoreactivity (E).