Astrocytes Coordinate Synaptic Networks: Balanced Excitation and Inhibition

摘要

Although neurons are essential for brain function, an emerging alternative view holds that astrocytes, the dominant glial cell type, coordinate synaptic networks. Through the release of glutamate, astrocytes locally excite neurons, and via adenosine,which accumulates due to the hydrolysis of released ATP, astrocytes suppress distant synapses. Looking at the relative structure of cells in the nervous system, one would infer that neurons, with their long axonal projections, are preeminent in brain function. Their rapid conduction velocity logically suggests that no other cells play essential signaling roles. Why then is there an emerging school of thought that the slow-signaling astrocyte, the more numerous nonneuronal cell of the nervous system, isa critical regulator ofneu-ronal function? What is the basis for this new idea of nervous system integration? In this discussion, we will bring together the results of a decade of work demonstrating that astrocytes listen and talk back to the synapse, work that leads us to conclude that astrocytes coordinate integration among neuronal and synaptic networks.