Physiology of microglial cells

Microglial cells in culture and in situ express a defined pattern of K+ channels, which is distinct from that of other glial cells and neurons. This pattern undergoes defined changes with microglial activation. As expected for a cell with immunological properties, microglia express a variety of cytokine and chemokine receptors, which are linked to the mobilization of Ca2+ (cytosolic free calcium) from internal stores. Microglial cells also have the capacity to respond to neuronal activity: they express receptors for the major excitatory receptor glutamate and the main inhibitory receptor GABA (γ-amino butyric acid). By expressing purinergic receptors, microglia can sense astrocyte activity in the form of Ca2+ waves. Activation of transmitter receptors can affect cytokine release which is a potential means as to how brain activity can affect immune function.