KCC2 function modulates in vitro ictogenesis.
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.
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.
Shabnam
S
Hamidi
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.
Massimo
M
Avoli
D015761:4-Aminopyridine; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D002540:Cerebral Cortex / Q000187:drug effects / Q000503:physiopathology*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004827:Epilepsy / Q000188:drug therapy / Q000503:physiopathology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D017207:Rats, Sprague-Dawley; D049994:Sodium Potassium Chloride Symporter Inhibitors / Q000494:pharmacology; D027981:Symporters / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines / Q000494:pharmacology; D013864:Thioglycolates / Q000494:pharmacology; D046509:Tissue Culture Techniques; D000096922:K Cl- Cotransporters
D015761:4-Aminopyridine; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D002034:Bumetanide; D018691:Excitatory Amino Acid Antagonists; D049994:Sodium Potassium Chloride Symporter Inhibitors; D027981:Symporters; D013844:Thiazoles; D053778:Thiazolidines; D013864:Thioglycolates; D000096922:K Cl- Cotransporters; C585828:CLP257; C572191:N-(4-methylthiazol-2-yl)-2-(6-phenylpyridazin-3-ylthio)acetamide
4-Aminopyridine; Entorhinal cortex; Epilepsy; GABA; High-frequency oscillations; KCC2; NKCC1; Piriform cortex