DA (TH-ir) neurons and terminals in AT1a-null mice. TH-ir neurons in the (A) SNc and (B) TH-ir terminals in the striatum one week after treatment with vehicle, GW9662 alone, MPTP alone, or MPTP + GW9662 in AT1a-null mice (AT1a-/-). The DA neurons were quantified as the total number of TH-ir neurons in the SNc, and density of striatal DA terminals was estimated as optical density and expressed as a percentage of the value obtained in the group treated with vehicle. Data are presented as mean ± SEM. *P < 0.05 compared with mice treated with vehicle, #
P < 0.05 compared with AT1a-null mice treated with MPTP alone, Ф
P < 0.05 compared with mice treated with MPTP + GW9662 (one-way ANOVA and Student-Newman-Keuls post-hoc test).