A1 astrocytes-secreted IL-1β, IL-6, IL-18 and TNF-α aggravate the neuroinflammation and deteriorate the brain tissue damage [113, 114].Whereas, A2 astrocytes produce brain-derived neurotrophic factor (BDNF), which is known as neurotrophic factor and provide neuroprotection against cerebral ischemia injury [115-117]. The gene discussed is BDNF; the disease is brain ischemia.