IFNG and Parkinson disease: Although IFN-γ has been linked to the death of dopaminergic neurons in PD models (10), contrasting findings indicate that low levels of IFN-γ in a chemically induced model of CNS demyelination exert protective effects on cuprizone-induced gliosis, oligodendrocyte death and the demyelination associated with the up-regulation of insulin-like growth factor-1 (IGF-1) (28, 29).