CDNF and Parkinson disease: Thereafter, the neuroprotective and neurorestorative effects of CDNF have been tested in various rodent models of PD, such as in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), and α-synuclein preformed fibril (PFF)-induced PD models1,3,13–18.