Calcium signalling in glial cells

Various electrical, mechanical, and chemical stimuli, including the influences of neurotrasmitters, neuromodulators, and hormones, trigger complex changes in Ca²⁺] _i in all types of glial cells. Glial Ca²⁺] _i responses are controlled by coordinated activity of several molecular cascades. The initiation of Ca²⁺] _i signal in glial cells results from activation of either plasmalemmal, or intracellular Ca²⁺ permeable channels. The interplay of different molecular cascades enables the development of agonist-specific patterns of Ca²⁺ responses. Such agonist specificity may provide the means for intracellular and intercellular information coding. Furthermore, glial Ca²⁺] _i signals can travel with no decrement within glial networks. These intercellular Ca²⁺ waves can be regarded as a substrate for information exchange between the glial cells. Neuronal activity can trigger Ca²⁺] _i signals in neighboring glial cells and, moreover, there is some evidence that glial Ca²⁺] _i waves can activate neuronal electrical and/or Ca²⁺] _i , responses. Glial Ca²⁺ signalling can be regarded as a form of glial excitability.