Astrocyte: Calcium signaling

Cytosolic Ca²⁺ signals in astrocytes can be spontaneous or evoked, and they are often initiated by activation of metabotropic receptors, resulting in Ca²⁺ release from intracellular Ca²⁺ stores. Although voltage-dependent Ca²⁺ influx is rare in astrocytes, the refilling of the intracellular Ca²⁺ stores requires store-operated Ca²⁺ entry, a major influx pathway of Ca²⁺ into astrocytes. Astrocyte Ca²⁺ signals are generated in the form of transients or oscillations, which can be evoked by neurotransmitters, hormones, cytokines, and growth factors, often in response to neuronal activity. These Ca²⁺ signals are propagated along cellular processes and can travel from the point of origin across the tissue as Ca²⁺ waves. When propagated into astrocytic endfeet, they may release cyclooxygenase products to control cerebral blood flow. Astrocyte Ca²⁺ signaling may lead to the release of transmitters and may be one of the key mechanisms for allowing a complex dialogue between neurons and glial cells.