Huberfeld Gilles, Wittner Lucia, Clemenceau Stéphane, Baulac Michel, Kaila Kai, Miles Richard, Rivera Claudio
INSERM U739, Faculté de Médecine Pitié-Salpêtrière, Université Pierre et Marie Curie Paris 6, IFR70, CHU Pitié-Salpêtrière, 75013 Paris, France.
J Neurosci. 2007 Sep 12;27(37):9866-73. doi: 10.1523/JNEUROSCI.2761-07.2007.
Changes in chloride (Cl-) homeostasis may be involved in the generation of some epileptic activities. In this study, we asked whether Cl- homeostasis, and thus GABAergic signaling, is altered in tissue from patients with mesial temporal lobe epilepsy associated with hippocampal sclerosis. Slices prepared from this human tissue generated a spontaneous interictal-like activity that was initiated in the subiculum. Records from a minority of subicular pyramidal cells revealed depolarizing GABA(A) receptor-mediated postsynaptic events, indicating a perturbed Cl- homeostasis. We assessed possible contributions of changes in expression of the potassium-chloride cotransporter KCC2. Double in situ hybridization showed that mRNA for KCC2 was absent from approximately 30% of CaMKIIalpha (calcium/calmodulin-dependent protein kinase IIalpha)-positive subicular pyramidal cells. Combining intracellular recordings with biocytin-filled electrodes and KCC2 immunochemistry, we observed that all cells that were hyperpolarized during interictal events were immunopositive for KCC2, whereas the majority of depolarized cells were immunonegative. Bumetanide, at doses that selectively block the chloride-importing potassium-sodium-chloride cotransporter NKCC1, produced a hyperpolarizing shift in GABA(A) reversal potentials and suppressed interictal activity. Changes in Cl- transporter expression thus contribute to human epileptiform activity, and molecules acting on these transporters may be useful antiepileptic drugs.
氯离子（Cl-）稳态的变化可能参与了某些癫痫活动的产生。在本研究中，我们探究了内侧颞叶癫痫伴海马硬化患者组织中Cl-稳态以及由此产生的γ-氨基丁酸能信号是否发生改变。从该人体组织制备的脑片产生了起源于海马下托的自发性发作间期样活动。少数海马下托锥体细胞的记录显示，γ-氨基丁酸A（GABA(A)）受体介导的突触后事件出现去极化，表明Cl-稳态受到干扰。我们评估了氯化钾共转运体KCC2表达变化可能产生的影响。双重原位杂交显示，约30%的钙调蛋白依赖蛋白激酶IIα（CaMKIIα）阳性海马下托锥体细胞中不存在KCC2的信使核糖核酸（mRNA）。将细胞内记录与生物素填充电极及KCC2免疫化学相结合，我们观察到在发作间期事件中发生超极化的所有细胞对KCC2免疫阳性，而大多数去极化细胞免疫阴性。布美他尼以选择性阻断氯离子导入性钾钠氯共转运体NKCC1的剂量处理时，使GABA(A)反转电位发生超极化偏移并抑制了发作间期活动。因此，Cl-转运体表达的变化促成了人类癫痫样活动，作用于这些转运体的分子可能是有用的抗癫痫药物。
