TNF and neurodegenerative disease: Excess activation of microglia due to brain injury or exposure to chemical stimuli causes excessive release of various neurotoxic substances, such as nitric oxide (NO), prostaglandin E2, superoxide and proinflammatory cytokines, such as interleukin-6 (IL-6), IL-1β and tumor necrosis factor-α (TNF-α) [3], which have been implicated in various neurodegenerative diseases.