Mechanism of anoxic depolarization in the brain disruption. Other consequential damage that occurs includes lipolysis, proteolysis, cell swelling, microtubule disaggregation, and DNA fragmentation. Neurons are more susceptible to brain ischemia than the supporting glial cells, because neurons have higher energy demand, conduct an action potential, and produce glutamate, whereas glial cells lack those properties. Yet neurons differ among themselves in their sensitivity to ischemia, depending on the specific properties they exhibit, relating to their locations in the brain. "Selective vulnerability" is the term used to describe how some parts of the brain are more sensitive to anoxia than others, and thus to ischemic insult. Anoxia-prone cells in
Glial scar of the injury increase gene expression, thus compounding the response of other astrocytes and contributing to the heterogeneity. Particularly, astrocytes closest to the lesion generally secrete more inhibitory molecules into the extracellular matrix. Microglia are the second most prominent cell type present within the glial scar. They are the nervous system analog of immune system macrophages. Microglia rapidly activate near the injury and secrete several cytokines, bioactive lipids, coagulation factors, reactive oxygen intermediates, and neurotrophic factors. The expression of these molecules depends on the location of the microglial cells relative to the injury, with the cells closest to the injury