Metabolic dysfunction during neuronal activation in the ex vivo hippocampus from chronic epileptic rats and humans
Metabolic dysfunction during neuronal activation in the ex vivo hippocampus from chronic epileptic rats and humans
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DOI：
10.1093/brain/awh568
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发表时间：
2005-10-01
期刊：
影响因子：
14.5
通讯作者：
Heinemann, U
中科院分区：
文献类型：
--
作者：
Kann, O;Kovács, R;Heinemann, U
代谢功能障碍与颞叶癫痫（TLE）的发病机制有关，但其在颞叶癫痫患者离体海马神经元激活中的表现尚未得到证实。我们对匹罗卡品治疗的慢性癫痫大鼠和耐药TLE患者的急性海马切片的代谢和线粒体功能进行了表征。NAD(P)H荧光的记录表明细胞能量代谢的状态，同时监测细胞外钾浓度（[K+](o)）使我们能够控制神经元激活的诱导。在对照大鼠中，电刺激引起双相NAD(P)H荧光瞬态，其特征是短暂的初始“下降”和随后的长时间“超调”，与增强的NAD(P)（+）还原相关。在慢性癫痫大鼠中，CA1区域的过冲明显较小，但与对照组相比，枕下没有过冲。经组织病理学分有无阿蒙角硬化组（AHS和非AHS）的TLE患者，齿状回、CA3、CA1和骨下均可见NAD(P)H瞬时值大滴和极少量过调。然而，通过线粒体特异性、电压敏感染料（罗丹明-123）监测线粒体膜电位（δ Psi(m)），发现对照组和慢性癫痫大鼠CA1区谷氨酸和质子团激活神经元时，线粒体的反应相似。应用共聚焦激光扫描显微镜，这些发现在AHS组织的单个神经元中得到证实，表明负的δ Psi(m)和激活依赖的线粒体去极化。我们的数据表明，慢性癫痫大鼠和人类海马神经元激活过程中存在严重的代谢障碍，尽管线粒体维持负δ Psi(m)。因此，我们的研究结果为癫痫患者的“低代谢”提供了细胞相关性，并提示TLE存在线粒体酶缺陷。
Metabolic dysfunction has been implicated in the pathogenesis of temporal lobe epilepsy (TLE), but its manifestation during neuronal activation in the ex vivo hippocampus from TLE patients has not been shown. We characterized metabolic and mitochondrial functions in acute hippocampal slices from pilocarpine-treated, chronic epileptic rats and from pharmaco-resistant TLE patients. Recordings of NAD(P)H fluorescence indicated the status of cellular energy metabolism, and simultaneous monitoring of extracellular potassium concentration ([K+](o)) allowed us to control the induction of neuronal activation. In control rats, electrical stimulation elicited biphasic NAD(P)H fluorescence transients that were characterized by a brief initial 'drop' and a subsequent prolonged 'overshoot' correlating to enhanced NAD(P)(+) reduction. In chronic epileptic rats, overshoots were significantly smaller in area CA1, but not in the subiculum as compared to controls. In TLE patients, who were histopathologically classified in groups with and without Ammon's horn sclerosis (AHS, non-AHS), large drops and very small overshoots of NAD(P)H transients were observed in dentate gyrus, CA3, CA1 and subiculum. Nevertheless, monitoring mitochondrial membrane potential (Delta Psi(m)) by mitochondria-specific, voltage-sensitive dye (rhodamine-123) revealed similar mitochondrial responses during neuronal activation with glutamate and protonophore application in area CA1 of control and chronic-epileptic rats. Applying confocal laser scanning microscopy, these findings were confirmed in individual neurons of AHS tissue, indicating a negative Delta Psi(m) and activation-dependent mitochondrial depolarization. Our data demonstrate severe metabolic dysfunction during neuronal activation in the hippocampus from chronic epileptic rats and humans, although mitochondria maintain negative Delta Psi(m). Thus, our findings provide a cellular correlate for 'hypometabolism' as described for epilepsy patients and suggest mitochondrial enzyme defects in TLE.