Figure 3.

Diagram summarizing the functions of activated macroglia. Under conditions of tissue stress that might represent a risk to neuronal survival, glial cells undergo reactive gliosis. The aim of acute gliosis is to protect the nervous tissue by reestablishing the extracellular medium and by supplementing neurons with factors that promote their survival (in green). An uncontrolled response (in blue), as occurs in most neurodegenerative diseases, will harm the tissue [BRB: blood-retinal barrier; ET: endothelin; GDNF: glial cell derived neurotrophic factor; GLAST: glutamate aspartate transporter; MHC: major histocompatibility complex; NO: nitric oxide; RGC: retinal ganglion cell; VEGF: vascular endothelium growth factor].