PPARG and Parkinson disease: Peroxisome proliferator-activated receptors-γ (PPARγ) is a ligand-activated transcription factor that plays a role in regulating PGC1α expression (36), and the PPARγ agonists such as pioglitazone or rosiglitazone have been shown to stimulate mitochondrial biogenesis and enhance mitochondrial function in conditions such as Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease (37, 38).