The levels of SIRT1 in dopaminergic neurons are sharply decreased by treatment with neurotoxins, such as rotenone, 6-hydroxydopamine, α-synuclein, or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; Alvira et al., 2007; Pallas et al., 2008; Albani et al., 2009), which are agents widely used to model PD. Here, SIRT1 is linked to Parkinson disease.