Hamidi Shabnam, Avoli Massimo
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.
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.
Neurobiol Dis. 2015 Jul;79:51-8. doi: 10.1016/j.nbd.2015.04.006. Epub 2015 Apr 26.
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.
GABAA受体介导的抑制作用是活跃的，可能有助于癫痫样同步化。抑制作用的效力依赖于细胞内低水平的Cl(-)，而这由KCC2的活性控制。这一证据促使我们通过场电位记录来分析KCC2阻滞剂VU0240551（10 μM）或布美他尼（50 μM）以及KCC2增强剂CLP257（100 μM）对体外脑片制备中梨状皮质和内嗅皮质（分别为PC和EC）产生的癫痫样放电的影响。在应用4-氨基吡啶（4AP，50 μM）期间，从这两个区域记录到了发作期和发作间期样放电以及高频振荡（HFOs，涟漪：80 - 200 Hz，快速涟漪：250 - 500 Hz）。用VU024055或高剂量布美他尼阻断KCC2活性可消除PC和EC中的发作期放电；此外，这些实验操作还缩短了发作间期放电的发生间隔和持续时间。相反，用CLP257增强KCC2活性则增加了两个区域发作期放电的持续时间。最后，阻断KCC2活性缩短了药理学分离的同步GABA能事件的持续时间和幅度，而增强KCC2活性则导致其持续时间增加。我们的数据表明，在体外，抑制或增强KCC2活性分别会消除或促进癫痫发作的产生。我们提出，这些效应可能是由于已知依赖于KCC2功能的细胞外K(+)的GABAA受体依赖性增加的减少所致。
