Astrocytic Regulation of Sleep Processes

Abstract

It is increasingly evident that astrocytes, once considered primarily a passive support cell type, in fact respond to and regulate neurotransmission to influence information processing and behavior. Although astrocytes are not electrically excitable, they express a variety of receptors that produce calcium responses able to propagate within and between astrocytes. This form of signaling occurs on spatial and temporal scales distinct from those of neuronal activity, potentially allowing astrocytes to locally regulate synaptic and network activity over extended time periods. Perhaps the best studied example of this regulation is the control of sleep homeostasis by astrocytes. Astrocyte-derived adenosine causes an increase in sleep pressure leading to increased slow wave activity and extended recovery sleep. Despite its established importance for the sleep homeostat, however, the roles of astrocytes in other sleep-associated processes are only beginning to be understood.