Contribution of astrocytes to synaptic transmission in the rat supraoptic nucleus.
Neurochemistry International. 2004-07-01; 45(2-3): 251-257
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1. Neurochem Int. 2004 Jul-Aug;45(2-3):251-7.
Contribution of astrocytes to synaptic transmission in the rat supraoptic
Piet R(1), Poulain DA, Oliet SH.
(1)Inserm U.378, Institut François Magendie, Université Victor Segalen Bordeaux
2, 33077 Bordeaux, France.
Astrocytes, besides supporting metabolic and scaffolding functions, play a
prominent role in the modulation of neuronal communication. In particular, they
are responsible for clearing synaptically-released glutamate via highly specific
transporters located on their plasma membrane. Since glutamate is the main
excitatory neurotransmitter in the central nervous system (CNS), astrocytes are
likely to play a central role in the regulation of synaptic processing and
overall cellular excitability. We recently investigated the influence of
astrocytes on glutamatergic and GABAergic transmission in the rat supraoptic
nucleus (SON) of the hypothalamus. This nucleus is part of the
hypothalamus-neurohypophysial system (HNS), which constitutes a conspicuous
example of activity-dependent neuroglial plasticity, in which certains
physiological conditions, such as parturition, lactation, and dehydration are
accompanied by a structural remodeling of the neurones, their synaptic inputs and
their surrounding glia. The use of pharmacological inhibitors of glutamate
transporters on this model, in which a physiological change in the astrocyte
environment occurs, has brought new insights on the contribution of astrocytes to
both excitatory and inhibitory neurotransmissions. The astrocytic environment of
neurons appears to control glutamate uptake and diffusion in the extracellular
space. This has direct repercussions on the tonic level of activation of
presynaptic glutamate receptors and, as a consequence, on the release of
neurotransmitter. This short review summarizes data obtained so far, which
clearly support the view that astrocytes are indeed a third partner in synaptic
transmission, and which show that the supraoptic nucleus represents a remarkable
model to study dynamic physiological interactions between astrocytes and neurons.
PMID: 15145540 [Indexed for MEDLINE]