GP-EX has protective effects against 6-OHDA-induced neurotoxicity by reducing tyrosine hydroxylase neuronal cell death in the 6-OHDA lesioned rat model of PD [13] and butanol extracts of GP also protect against the chronic EF stress, which reduces L-DOPA-induced neuronal cell death in 6-OHDA-lesioned rats treated with L-DOPA [33]. This evidence concerns the gene TH and Parkinson disease.