TNF and Parkinson disease: These cells change their conformation and take on multiple different phenotypes,causing them to lose much of their normal functions and take on an inflammatory role.Activation of microglia following injury leads to the conversion of astrocytes into an “A1”phenotype that is more neuro-toxic in (Parkinson's Disease and optic nerve crush models).Three cytokines, tumor necrosis factor (TNF), interleukin 1a (Il-1a), and complementcomponent 1q (C1q) are released from microglia and have been determined to induce the A1astrocyte phenotype.