Anomalous levels of Cl- transporters in the hippocampal subiculum from temporal lobe epilepsy patients make GABA excitatory
Anomalous levels of Cl- transporters in the hippocampal subiculum from temporal lobe epilepsy patients make GABA excitatory
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DOI：
10.1073/pnas.0602979103
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发表时间：
2006-05-30
影响因子：
11.1
通讯作者：
Eusebi, F.
中科院分区：
文献类型：
--
作者：
Palma, E.;Amici, M.;Eusebi, F.
在手术切除的耐药颞叶（TL）癫痫（TLE）患者脑标本中，研究了NKCC 1（一种促进细胞内Cl-蓄积的内向Na+，K+-2Cl（-）协同转运蛋白）和KCC 2（一种挤出Cl-的外向K+-Cl-协同转运蛋白）的mRNA水平。定量RT-PCR分析从人类颞叶癫痫相关脑区提取的mRNA显示，上调NKCC 1 mRNA和下调KCC 2 mRNA的海马下托，与海马适当的或TL新皮质相比，表明在颞叶癫痫下托的Cl-转运蛋白的异常转录。在平行实验中，将从相同的TLE相关脑区分离的细胞膜注射到非洲爪蟾卵母细胞中，这些卵母细胞迅速将人GABA（A）受体整合到其表面膜中。与海马或新皮层相比，注射下托膜的卵母细胞诱发的GABA电流具有更强的去极化反转电位（E-GABA）。NKCC 1阻滞剂bumetanicle或温度降低10摄氏度，将GABA电流的EGABA更负的TLE海马下托的膜注射的卵母细胞，匹配的TL neocortex注射的卵母细胞的EGABA。我们的结论是，在TLE海马下托的Cl-转运蛋白，KCC 1和NKCC 2的异常表达可能会导致改变Cl-运输的“癫痫”神经元，揭示在微移植的非洲爪蟾卵母细胞，并呈现GABA aberrantly“兴奋”，一个功能，可能有助于癫痫发作的沉淀。
The mRNA levels of NKCC1, an inwardly directed Na+, K+-2Cl(-) cotransporter that facilitates the accumulation of intracellular Cl-, and of KCC2, an outwardly directed K+-Cl- cotransporter that extrudes Cl-, were studied in surgically resected brain specimens from drug-resistant temporal lobe (TL) epilepsy (TLE) patients. Quantitative RT-PCR analyses of the mRNAs extracted from the human TLE-associated brain regions revealed an up-regulation of NKCC1 mRNA and a down-regulation of KCC2 mRNA in the hippocampal subiculum, compared with the hippocampus proper or the TL neocortex, suggesting an abnormal transcription of Cl- transporters in the TLE subiculum. In parallel experiments, cell membranes isolated from the same TLE-associated brain regions were injected into Xenopus oocytes that rapidly incorporated human GABA(A) receptors into their surface membrane. The GABA currents elicited in oocytes injected with membranes from the subiculum had a more depolarized reversal potential (E-GABA) compared with the hippocampus proper or the neocortex. The NKCC1 blocker bumetanicle or a temperature decrease of 10 degrees C shifted the GABA-current EGABA more negative in oocytes injected with membranes from TLE hippocampal subiculum, matching the EGABA of TL neocortex-injected oocytes. We conclude that the anomalous expression of both Cl- transporters, KCC1 and NKCC2, in TLE hippocampal subiculum probably causes altered Cl- transport in the "epileptic" neurons, as revealed in the microtransplanted Xenopus oocytes, and renders GABA aberrantly "exciting," a feature that may contribute to the precipitation of epileptic seizures.