Gliotransmission at Tripartite Synapses
Signal exchange between astrocytes and neurons at tripartite synapses has emerged as a crucial element of neural circuits in the brain. The position of astrocyte processes facing synapses provides the proper structural and functional conditions for neuron-astrocyte communication giving rise to the concept of “tripartite synapse”. These synapses envisage an active role for astrocytes in their function whereby: (i) astrocytes sense neurotransmission by neurotransmitter transporter and receptors; (ii) synaptic activity stimulates astrocytic intracellular Ca2+ levels; (iii) astrocytes release neuroactive substances, gliotransmitters, that in turn regulate neuronal excitability and synaptic transmission. The ability of astrocytes to release different gliotransmitters and modulate synaptic activity deepens our knowledge of the brain physiology. In addition to the traditional homeostatic roles in the extracellular ion balance, neurotransmitter uptake from the extracellular space, and metabolic energy supply to neurons, astrocytes play active roles in synaptic transmission and plasticity, being involved in the coding information and cognitive processes by brain networks.
KeywordsAstrocytes Gliotransmission Tripartite synapse Synaptic plasticity Information coding
The authors would like to thank Dr. Washington Buño for his helpful comments on the manuscript. This work was supported by grants from Ministerio de Economia y Competitividad, Spain, MINECO: Consolider, CSD2010-00045; Ramón y Cajal Program, RYC-2012-12014; and BFU2013-47265R.
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