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Circuit-specific signaling in astrocyte-neuron networks in basal ganglia pathways

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Science  14 Aug 2015:
Vol. 349, Issue 6249, pp. 730-734
DOI: 10.1126/science.aaa7945

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Cell type–specific glial networks

Glial cells respond to neurotransmitters when nerve cells communicate with each other. Glial cells themselves release gliotransmitters that regulate neural synaptic transmission. Martín et al. studied this reciprocal relationship in a brain region called the dorsal striatum, which has two types of experimentally identifiable neurons and two types of synapses (see the Perspective by Gittis and Brasier). Subpopulations of glial cells selectively responded to the activity of one specific type of neuron. In turn, these specifically activated glial cells signaled only to the same type of neurons but not the other, indicating that glial-nerve signaling is largely cell-type specific.

Science, this issue p. 730; see also p. 690

Abstract

Astrocytes are important regulatory elements in brain function. They respond to neurotransmitters and release gliotransmitters that modulate synaptic transmission. However, the cell- and synapse-specificity of the functional relationship between astrocytes and neurons in certain brain circuits remains unknown. In the dorsal striatum, which mainly comprises two intermingled subtypes (striatonigral and striatopallidal) of medium spiny neurons (MSNs) and synapses belonging to two neural circuits (the direct and indirect pathways of the basal ganglia), subpopulations of astrocytes selectively responded to specific MSN subtype activity. These subpopulations of astrocytes released glutamate that selectively activated N-methyl-d-aspartate receptors in homotypic, but not heterotypic, MSNs. Likewise, astrocyte subpopulations selectively regulated homotypic synapses through metabotropic glutamate receptor activation. Therefore, bidirectional astrocyte-neuron signaling selectively occurs between specific subpopulations of astrocytes, neurons, and synapses.

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