齿状回在慢性电刺激诱发大鼠颞叶癫痫中的可能作用

本文探讨了齿状回（DG）及海马（HPC）在颞叶癫痫发生中的可能作用,分别强直电刺激（60Hz,0.4-0.6mA,2s)大鼠右背侧海马（DHPC）和DG制作慢性癫痫模型,观察大鼠行为,深部电图及脑区T2加权核磁共振成像（T2－WI)的改变,发现DG刺激组大鼠的原发性湿狗样抖频率明显低于HPC刺激组（P＜0．05）,其深部电图脑波的平均最高振幅也明显低于HPC刺激组大鼠（P＜0．05）,而PC电图的电振荡发生率增加,另外,HPC刺激组大鼠呈现T2－WI高信号强度,而DG刺激组大鼠T2－WI信号强度无明显改变（P＜0．05）,结果表明,DG在内嗅皮质（EC）－HPC环路中可能起着某种“过滤器”的作用,限制来自于大脑皮层通过EC到达HPC的神经信息,一旦丧失该作用可以导致HPC的损害并发生颞叶癫痫。

Possible role of dentate gyrus in greneration of rat temporal lobe epilepsy induced by electrical stimulation

Possible role of the dentate gyrus (DG) and the hippocampus (HPC) in temporal lobe epileptogensis was investigated in an electrogertic model of rat epilepsy. Chronic tetani (60 Hz, 0.4-0.6 mA, 2 s) were administered once daily for 7 days to the right dorsal hippocampus (DHPC) or the right DG. Animal behavior was observed and depth electro-graphic seizures and T2-weight- ed magnetic resonance images (T2- WI) were measured. Results indicated that the frequency of primary wet dog shakes (WEDS) in the DG-stimulated rats was much lower than that in the DHPC-stimulated rats (P < 0.05). The mean maximal wave-amplitude in DG electrographs was also much lower than that in HPC electrographs (P < 0.05). The oscillations proportion of DHPC elcctro-graphs increased after DHPC-tetanization (from 2/9 up to 7/9 rats). T2-WI hyperintensity in the lateral ventricle area was detected only in the DHPC-tetanized rats, not in the DG-tetanized rats (P <0.05). These results suggest that the DG acts as a filtering site in the entorhinal cortex-HPC neuronal circuitry and its dysfunction causes damage to the HPC and the generation of temporal lobe epilepsy.