Characterization of molecular events leading to seizure susceptibility in ethacrynic acid-induced seizure model.

癫痫发作引起的神经元改变导致中枢神经系统易感神经元回路的长期重组，最终导致长期癫痫发作易感性。我们之前报道了脑室内给药乙酸（EA）诱导小鼠反复强直阵挛性惊厥。我们的目的是在这个癫痫模型中证明导致癫痫易感性的分子和细胞事件，与即时早期基因c-fos的表达有关。对c-fos mRNA长期表达的研究显示，c-fos mRNA的表达呈双相增加，在ea给药后60分钟（早期）出现短暂增加，在10-14天（晚期）持续增加，在齿状回和梨状皮质中表现最为明显。NGF是一种参与神经回路重组的神经营养因子，其表达也呈双相性增加，且与c-fos表达具有密切的时空相关性。此外，免疫组织化学分析显示，在ea发作后第7天，小白蛋白（PARV）阳性细胞（gaba能中间神经元亚群）的树突明显减少，第14天它们的细胞体细胞也减少。此外，我们观察了ea治疗小鼠在第14天癫痫发作敏感性的发展。腹腔注射亚惊厥剂量的kainic酸引起严重（5期）癫痫发作，77%的小鼠从EA癫痫发作中恢复，70%的小鼠在10分钟内死亡。这些发现表明，短暂性ea诱导的癫痫发作通过c-fos表达的持续增加和随后NGF mRNA表达的增加而导致长期癫痫易感性的发展。此外，在c-fos表达的后期增加之前，parv阳性细胞的丢失被认为在发展中起因果作用。

Neuronal alterations by seizures produce a long-lasting reorganization of susceptible neuronal circuity in the central nervous system, culminating in long-term seizure susceptibility. We previously reported that an intracerebroventricular administration of ethacrynic acid (EA) to mice induced repeated tonic-clonic convulsions. We aimed in this seizure model to demonstrate molecular and cellular events leading to the seizure susceptibility, in relation to the expression of immediate early gene c-fos. Studies on the long-term expression of c-fos mRNA revealed that the expression was increased biphasically, with a transient increase at 60 min (early phase) and a prolonged increase on the 10-14th day (late phase) post-EA administration, most remarkably in dentate gyrus and pyriform cortex. The expression of NGF,a neurotrophic factor supposed to play a role in the reorganization of neural circuity, also showed biphasic increases with a close spatiotemporal correlation with c-fos expression. In addition, immuno-histochemical analysis displayd that the dendrites of parvalbumin (PARV) -positive cells, a subpopulation of GABAergic interneurons, were markedly decreased on the 7th day post-EA seizure and that their cell somata also decreased on 14th day. Furthermore, we examined the development of seizure susceptibity in EA-treated mice on the 14th day. Intraperitoneal injection with subconvulsive dose of kainic acid caused severe (stage 5) seizure in 77% of mice recovered from EA seizure with 70% mortality within 10 min. These findings suggest that the transient EA-induced seizures produce the development of long-term seizure susceptibility via prolonged increase in c-fos expression and subsequent increase in NGF mRNA expression. Also, it was supposed that the loss of PARV-positive cells which precede the late phase increase in c-fos expression play a causal role in the development.