(a) Effects of DTT and MsrA on the brain activity of COMT in WT and MsrA KO mice, and (b) Effects of aging on COMT activity in WT and MsrA KO mice. Values are displayed as means ± SEM. All analyses were run by 2-way ANOVAs, followed by Newman-Keuls test for post-hoc comparisons. ###, P<0.001 for comparisons vs corresponding WT group (Main genotype effect); °°°, P<0.001 for comparison vs 2mM DTT (Main treatment effect); ^^^, P<0.01 for comparison vs 20mM DTT (Main treatment effect); $$$, P<0.001 for comparison vs 6 months (Main age effect).