Increased 3-NT levels in the brains of APP/PS-1 mice: 3-NT levels in brains from different age groups (1, 2, 3, 6, 9, 12 and 15 month old) of APP/PS-1 (solid bars) and wild type mice (plain bars) were compared with the control (brain of 1 month old wild type mice). Results shown are mean ±SEM obtained from five independent preparations (5 animals/age group). Significance was assessed by two-way ANOVA followed by Scheff’s post-hoc test. *p < 0.05.