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Neurobiol Dis. 2015 Jul;79:51-8. doi: 10.1016/j.nbd.2015.04.006. Epub 2015 Apr 26.

KCC2 function modulates in vitro ictogenesis.

Author information

1
Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4 McGill University, 3801 University Street, Montréal, QC, Canada, H3A 2B4.
2
Montreal Neurological Institute and Department of Neurology & Neurosurgery, McGill University, 3801 University Street, Montréal, QC, Canada H3A 2B4 McGill University, 3801 University Street, Montréal, QC, Canada, H3A 2B4. Electronic address: massimo.avoli@mcgill.ca.

Abstract

GABAA receptor-mediated inhibition is active and may contribute to epileptiform synchronization. The efficacy of inhibition relies on low levels of intracellular Cl(-), which are controlled by KCC2 activity. This evidence has led us to analyze with field potential recordings the effects induced by the KCC2 blockers VU0240551 (10 μM) or bumetanide (50 μM) and by the KCC2 enhancer CLP257 (100 μM) on the epileptiform discharges generated by piriform and entorhinal cortices (PC and EC, respectively) in an in vitro brain slice preparation. Ictal- and interictal-like discharges along with high-frequency oscillations (HFOs, ripples: 80-200 Hz, fast ripples: 250-500 Hz) were recorded from these two regions during application of 4-aminopyridine (4AP, 50 μM). Blocking KCC2 activity with either VU024055 or high doses of bumetanide abolished ictal discharge in both PC and EC; in addition, these experimental procedures decreased the interval of occurrence and duration of interictal discharges. In contrast, enhancing KCC2 activity with CLP257 increased ictal discharge duration in both regions. Finally, blocking KCC2 activity decreased the duration and amplitude of pharmacologically isolated synchronous GABAergic events whereas enhancing KCC2 activity led to an increase in their duration. Our data demonstrate that in vitro ictogenesis is abolished or facilitated by inhibiting or enhancing KCC2 activity, respectively. We propose that these effects may result from the reduction of GABAA receptor-dependent increases in extracellular K(+) that are known to rest on KCC2 function.

KEYWORDS:

4-Aminopyridine; Entorhinal cortex; Epilepsy; GABA; High-frequency oscillations; KCC2; NKCC1; Piriform cortex

PMID:
25926348
PMCID:
PMC4880462
DOI:
10.1016/j.nbd.2015.04.006
[Indexed for MEDLINE]
Free PMC Article

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