Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts 02129, USA.
J Neurosci. 2013 May 22;33(21):9056-67. doi: 10.1523/JNEUROSCI.3870-12.2013.
mTOR is activated in epilepsy, but the mechanisms of mTOR activation in post-traumatic epileptogenesis are unknown. It is also not clear whether mTOR inhibition has an anti-epileptogenic, or merely anticonvulsive effect. The rat hippocampal organotypic culture model of post-traumatic epilepsy was used to study the effects of long-term (four weeks) inhibition of signaling pathways that interact with mTOR. Ictal activity was quantified by measurement of lactate production and electrical recordings, and cell death was quantified with lactate dehydrogenase (LDH) release measurements and Nissl-stained neuron counts. Lactate and LDH measurements were well correlated with electrographic activity and neuron counts, respectively. Inhibition of PI3K and Akt prevented activation of mTOR, and was as effective as inhibition of mTOR in reducing ictal activity and cell death. A dual inhibitor of PI3K and mTOR, NVP-BEZ235, was also effective. Inhibition of mTOR with rapamycin reduced axon sprouting. Late start of rapamycin treatment was effective in reducing epileptic activity and cell death, while early termination of rapamycin treatment did not result in increased epileptic activity or cell death. The conclusions of the study are as follows: (1) the organotypic hippocampal culture model of post-traumatic epilepsy comprises a rapid assay of anti-epileptogenic and neuroprotective activities and, in this model (2) mTOR activation depends on PI3K-Akt signaling, and (3) transient inhibition of mTOR has sustained effects on epilepsy.
mTOR 在癫痫中被激活，但在创伤后癫痫发生中 mTOR 激活的机制尚不清楚。也不清楚 mTOR 抑制是否具有抗癫痫发生作用，还是仅仅具有抗惊厥作用。使用创伤后癫痫的大鼠海马器官型培养模型来研究与 mTOR 相互作用的信号通路的长期（四周）抑制的效果。通过测量乳酸盐产生和电记录来量化癫痫发作活动，通过测量乳酸脱氢酶（LDH）释放和尼氏染色神经元计数来量化细胞死亡。乳酸盐和 LDH 测量与电描记活动和神经元计数分别具有良好的相关性。PI3K 和 Akt 的抑制阻止了 mTOR 的激活，并且与抑制 mTOR 一样有效地减少癫痫发作活动和细胞死亡。PI3K 和 mTOR 的双重抑制剂 NVP-BEZ235 也是有效的。雷帕霉素抑制 mTOR 减少了轴突发芽。雷帕霉素的晚期开始治疗可有效减少癫痫活动和细胞死亡，而雷帕霉素的早期终止治疗不会导致癫痫活动或细胞死亡增加。该研究的结论如下：（1）创伤后癫痫的器官型海马培养模型包括对抗癫痫发生和神经保护活性的快速测定，并且（2）mTOR 激活取决于 PI3K-Akt 信号转导，以及（3）mTOR 的短暂抑制对癫痫具有持续作用。
