TH and Parkinson disease: Moreover, (R)-ketamine but not (S)-ketamine could attenuate 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced reduction of dopamine transporter (DAT) and tyrosine hydroxylase (TH) in the striatum of mice, suggesting that (R)-ketamine may be a new prophylactic or therapeutic drug for Parkinson’s disease [8].