In an animal model of PD, in which degeneration of nigro-striatal dopaminergic neurons is obtained through sub-chronic administration of rotenone, a mitochondrial toxin, a treatment with VPA counteracted the death of nigral neurons and the 50% drop of striatal dopamine levels as well as the alpha-synuclein alterations caused by rotenone [90]. The gene discussed is SNCA; the disease is Parkinson disease.