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Neuronal and glial glutamate transporters shape synaptic signaling in the hyppocampus| old_uid | 3237 |
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| title | Neuronal and glial glutamate transporters shape synaptic signaling in the hyppocampus |
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| start_date | 2007/10/08 |
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| schedule | 11h30 |
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| online | no |
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| details | invité par Stéphane Oliet |
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| summary | Glutamate transporters maintain ambient glutamate at very low levels and limit the extent of extrasynaptic transmitter diffusion (“spillover”). In the hippocampus, the large majority of transporters are expressed in glial membranes, such that a physiological role for neuronal transporters remains unclear. The neuronal transporter EAAC1 is expressed in CA1 pyramidal cells in the perisynaptic membrane surrounding excitatory synapses made by Schaffer collateral/commissural fibers from CA3, suggesting that they may play a role in limiting activation of extrasynaptic receptors by spillover. Previous work in the lab suggests that this is the case in the rat hippocampus, and we have addressed this issue further by examining synaptic transmission in mice lacking the gene for EAAC1. While the glutamate concentration within the synaptic cleft appears to be similar in wild-type and knockout mice, transporter-mediated currents recorded from astrocytes indicate that EAAC1 slows the escape of glutamate from the perisynaptic region, suggesting that neuronal transporters buffer transmitter released from active synapses. Accordingly, spillover activation of NMDA receptors – particularly those containing the NR2B subunit – is enhanced in EAAC1 knockout mice. Results to be presented argue that neuronal transporters, by controlling activation of a subset of NMDA receptors, modulate the induction of synaptic plasticity. |
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| oncancel | lieu inhabituel |
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| responsibles | Deris |
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