Figure 1.

Role of glia in health and disease. This is a figure depicting some of the various roles glial cells can play under normal and pathological conditions. (A) In healthy conditions, astrocytes provide protective and metabolic support to neurons via the supply of trophic factors and metabolic products and via the reuptake of synaptic glutamate. In addition, some of the factors and gliotransmitters released are involved in inducing synaptic plasticity. Microglia are involved in synaptic pruning, canvassing extracellular space and phagocytosing apoptotic cells. NG2-glia act mainly as oligodendrocyte progenitor cells. When activated, they proliferate and differentiate into oligodendrocytes. Oligodendrocytes, on the other hand, support neurons metabolically, are neuroprotective, and provide a source of myelin necessary for proper propagation of action potential. These various functions of glia are all crucial for maintaining proper neuronal functioning and communication. (B) In pathological conditions, loss of different types of glia can result in loss of trophic support, loss of synaptic plasticity, excitotoxicity, inflammation, loss of myelination, etc. All of these effects can impair neuronal activity and function and ultimately behavior.