Longo B M, Mello L E
Department of Physiology, Universidade Federal se Sao Paulo-EPM, São Paulo SP, Brazil.
Epilepsy Res. 1998 Sep;32(1-2):172-82. doi: 10.1016/s0920-1211(98)00049-7.
In a previous study, we suggested a dissociation between spontaneous recurrent epileptic seizures (SRS) and hippocampal supragranular mossy fiber sprouting (MFS) in the pilocarpine model of epilepsy (PILO). One possible explanation, would be that SRS in the PILO model do not originate in the hippocampus and thus would not depend on MFS. In the present study, we investigated whether MFS is necessary for the SRS that develop after a small intrahippocampal dose of kainic acid (KA), a model where seizures are more likely to start in the hippocampus. Intrahippocampal injections of KA were performed in rats, with and without the concomitant administration of cycloheximide (CHX) (0.5 microg of KA and 6 microg of CHX). After injection, recording electrodes were positioned in the same stereotaxic location. Here again, CHX was able to completely block (5/8 animals) MFS, visualized by neo-Timm staining, without altering the frequency and intensity of spontaneous ictal and interictal EEG events. From these data, we can conclude that, in the intra-hippocampal KA model, MFS is not necessary for the occurrence of ictal events. We suggest that CHX can be used together with classic epileptogenic agents, as a means to study temporal lobe epilepsy (TLE) without the contributing effect of MFS--as seen in TLE patients with mass lesions in the lateral temporal lobe.
在之前的一项研究中，我们提出在毛果芸香碱癫痫模型（PILO）中，自发性反复癫痫发作（SRS）与海马颗粒上层苔藓纤维出芽（MFS）之间存在分离现象。一种可能的解释是，PILO模型中的SRS并非起源于海马体，因此不依赖于MFS。在本研究中，我们调查了在海马内小剂量注射 kainic 酸（KA）后发生的SRS中，MFS是否是必需的，在该模型中癫痫发作更有可能起始于海马体。对大鼠进行海马内注射KA，同时给予或不给予放线菌酮（CHX）（0.5微克KA和6微克CHX）。注射后，将记录电极置于相同的立体定位位置。同样，通过新Timm染色可视化，CHX能够完全阻断（5/8只动物）MFS，而不改变自发性发作期和发作间期脑电图事件的频率和强度。从这些数据中，我们可以得出结论，在海马内KA模型中，MFS对于发作期事件的发生不是必需的。我们建议CHX可以与经典的致癫痫剂一起使用，作为一种研究颞叶癫痫（TLE）的方法，而不受MFS的影响——就像在外侧颞叶有占位性病变的TLE患者中所看到的那样。
