Striatal catecholamine concentrations. MPTP reduces striatal dopamine (A), DOPAC (B), and HVA (C) concentrations, which partially recover between 14 and 90 days after MPTP treatment in DAT-Cre and Retlx but not in DAT-Retlx/lx mice. Numbers are means ± SD. For dopamine, DOPAC, and HVA, there were no significant differences among genotypes at 14 days after MPTP treatment. At 90 days, dopamine, DOPAC, and HVA from DAT-Retlx/lx mice were different from Retlx mice (P < 0.01) but not from DAT-Cre mice (two-way ANOVA followed by Tukey's post hoc test).