GDNF and Parkinson disease: It was also observed that rotarod walking exercise for 4 weeks and treadmill training for 10 and 18 weeks increased the expression of GDNF in mice with MPTP-induced Parkinson’s model, while evidence supported that 4 weeks of treadmill training increased the striatal GDNF level in the 6-OHDA-induced PD model (Tajiri et al., 2010; Soke et al., 2021).