Figure 2

Prodynorphin gene deficiency exacerbates striatonigral dopaminergic neurotoxicity induced by MPTP or MA. Dyn^+/+ and Dyn^−/− received MPTP (15 or 20 mg/kg, i.p./day × 7) or MA (5 or 7 mg/kg, i.p./2 h × 4) as described in Figure 1. Tyrosine hydroxylase (TH)-immunoreactive neurons were stained and counted 7 days after the last treatment with MPTP or MA by immunocytochemistry with an antibody against TH. Immunostaining of nigrostriatal TH-positive neurons treated with saline, MPTP (A), or MA (B) in Dyn^+/+ and Dyn^−/−. Immunostaining of striatal TH-positive fibers was quantified using ImageJ (C, D). Numbers of TH-positive neurons in the SN pars compacta were counted by stereological analyses (E, F). For more details, refer to ‘Methods’. ST = striatum. SN = substantia nigra. 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 = 400 μm.