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J Physiol. 2005 Aug 1;566(Pt 3):671-9. Epub 2005 Jun 16.

Early expression of KCC2 in rat hippocampal cultures augments expression of functional GABA synapses.

Author information

1
INMED/INSERM Unite 29, 163 Route de Luminy, 13009 Marseille, France.

Abstract

The development of GABAergic synapses is associated with an excitatory to inhibitory shift of the actions of GABA because of a reduction of [Cl-]i. This is due to a delayed postnatal expression of the K+ -Cl- cotransporter KCC2, which has low levels at birth and peaks during the first few postnatal weeks. Whether the expression of the cotransporter and the excitatory to inhibitory shift have other consequences on the operation of GABA(A) receptors and synapses is not yet known. We have now expressed KCC2 in immature neurones at an early developmental stage and determined the consequences on the formation of GABA and glutamate synapses. We report that early expression of the cotransporter selectively enhances GABAergic synapses: there is a significant increase of the density of GABA(A) receptors and synapses and an increase of the frequency of GABAergic miniature postsynaptic currents. The density of glutamate synapses and frequency of AMPA miniature postsynaptic currents are not affected. We conclude that the expression of KCC2 and the reduction of [Cl-]i play a critical role in the construction of GABAergic networks that extends beyond the excitatory to inhibitory shift of the actions of GABA.

PMID:
15961425
PMCID:
PMC1464776
DOI:
10.1113/jphysiol.2005.089821
[Indexed for MEDLINE]
Free PMC Article

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