SIRT1 and Parkinson disease: In a PD mice model, SIRT1 was found downregulated in neuron, which leading to FOXO1 acetylation upregulation, and subsequently increased the transcription level of type A monoamine oxidase (MAO-A), an enzyme primarily engaged in catalyzing the oxidative deamination of NA and 5-HT and leading to inactivation and degradation of both monoamines.