NOS2 and Parkinson disease: However, sustained excessive activation of microglia leads to neuronal damage and the release of neurotoxic substances, including nitric oxide (NO), tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX)-2, all of which are implicated in neurodegenerative disorders including Alzheimer’s disease, Parkinson’s disease, and stroke [2,3].