Albeit the usefulness of 6-OHDA-induced PD model was demonstrated by the METH-induced motor function tests in the evidence above and in the current study (Jagmag et al., 2015; Gomez-Paz et al., 2018), quantification analysis of TH-ir striatal and nigral cells, as well as additional motor behavior studies such as gait analysis and forelimb akinesia, provide stronger assessment of the extent of neurotoxin, i.e., MPTP or 6-OHDA in this study, elicited lesions of nigrostriatl DA neurons. This evidence concerns the gene TH and Parkinson disease.