TH and Parkinson disease: Figures 5B,C shows immunostaining for TH in rat SNc and striatum, with obviously lower numbers of TH-immunoreactive cells and fibers on the lesioned side relative to the unlesioned side. Compared with the control group, 6-OHDA-lesioned rats had significantly reduced nigrostriatal projections in both the PD and PD + Ex groups (P < 0.01). The exercise intervention was unable to significantly reverse the nigrostriatal depletion in these groups (P > 0.05, Figures 5D,E).