TH and Parkinson disease: Recently, accumulated data indicated that APα increased the number of total cells, tyrosine hydroxylase (TH) positive cells, and newly formed (BrdU positive) TH expressing cells in the substantia nigra (SN), and improved the balance and coordination of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mice, an animal model for Parkinson’s disease (PD; Adeosun et al., 2012).