Glial modulation of synaptic transmission: Insights from the supraoptic nucleus of the hypothalamus.
Glia. 2004-01-01; 47(3): 258-267
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1. Glia. 2004 Aug 15;47(3):258-67.
Glial modulation of synaptic transmission: Insights from the supraoptic nucleus
of the hypothalamus.
Oliet SH(1), Piet R, Poulain DA, Theodosis DT.
(1)INSERM U378, Institut François Magendie, Université Victor Segalen Bordeaux 2,
Astrocytes clear synaptically released glutamate from the extracellular space
through high-affinity transporters present on their plasma membrane. By
controlling the extracellular level of the main excitatory transmitter in the
central nervous system, astrocytes thus contribute prominently to the regulation
of overall cellular excitability and synaptic information processing. We recently
investigated the influence of the glial environment on glutamatergic and
GABAergic neurotransmission in the supraoptic nucleus of the rat hypothalamus
under physiological conditions such as lactation that significantly reduce
astrocytic coverage of its neurons. By performing electrophysiological analyses
on this unique model of dynamic neuronal-glial interactions, we have been able to
show that the fine astrocytic processes normally enwrapping synapses serve two
important functions. First, they govern the level of activation of presynaptic
metabotropic glutamate receptors on glutamatergic terminals, thereby regulating
synaptic efficacy at excitatory synapses. Second, they act as a physical and
functional barrier to diffusion in the extracellular space, limiting spillover of
glutamate and other neuroactive substances and therefore contributing to the
regulation of heterosynaptic transmission and intercellular communication.
Copyright 2004 Wiley-Liss, Inc.
PMID: 15252815 [Indexed for MEDLINE]