TH-positive neurons in the SN were dramatically decreased by 6-OHDA injection in the PD group (62.8 ± 2.7, Figure 5) in comparison to the control (147.2 ± 3.7, F = 1.869, R2 = 0.9541, P<0.001) and the Sham (139.0 ± 6.1, F = 5.096, R2 = 0.8885, P<0.001) groups of rats. The gene discussed is TH; the disease is Parkinson disease.