Figure 4

Prodynorphin deficiency amplifies activation of microglia induced by MPTP or MA in the striatonigral areas. Dyn^+/+ and Dyn^−/− received MPTP (20 mg/kg, i.p./day × 7) or MA (7 mg/kg, i.p./2 h × 4) as described in Figure 1. Microglial activation induced by MPTP or MA was examined by immunocytochemistry with an antibody against Iba1. Striatal sections were collected at 0.62 mm anterior to bregma, while nigral sections were collected at 3.08 mm posterior to bregma according to the atlas of Franklin and Paxinos (2008). Representative photomicrographs of Iba1-immunoreactive cells in the striatum (ST) and substantia nigra (SN) of mice after the last treatment with saline, MPTP, or MA are shown (A, B). Immunostaining of striatal Iba1 immunoreactivity (Iba-1-IR) was quantified by immunoreactive density (C, D) and the number of Iba1-positive neurons in the SN pars compacta was counted by stereological analysis (E, F). For more details, refer to ‘Methods’. Each value is mean ± S.E.M of eight mice. *P <0.05, **P < 0.01, ***P < 0.001 vs. respective saline group, #P <0.05, ##P <0.01 vs. MPTP- or MA-treated Dyn^+/+ (two-way ANOVA followed by post-hoc Tukey HSD test or pairwise comparison with paired t-test). Scale bar = 50 μm.