Accordingly, TH (a marker of dopaminergic neurons) protein expressions (Figure 1G and Supplementary Figure 2A) and its immunohistochemistry (IHC) staining (Figure 1E) in the SNpc of PD mice declined greatly (p < 0.01 vs. Normal); and DA content in the striatum (p < 0.05 vs. Normal; Table 1) reduced significantly in such a chronic PD mice model. Here, TH is linked to Parkinson disease.