Animal model of juvenile epileptogenesis: NMDA receptors

描述(申请人提供)：可能与遗传易感性有关 在超过40%-50%的人类癫痫中。然而，到目前为止，只有12个基因 与人类癫痫综合征有关，而这些只能解释 不到1%的癫痫患者。进一步鉴定基因是 有关癫痫的发病机制对了解癫痫是如何发生的至关重要 发展，并最终可能导致更好的治疗和预防 疾病。我们已经建立了一种独特的突变动物模型，在该模型中，NMDA谷氨酸 大脑皮层和海马区的受体被选择性地敲除。 与出生后不久死亡的标准NMDA基因敲除突变小鼠不同，我们的突变小鼠 小鼠存活数周，但在晚期会出现癫痫发作活动 青春期(出生后3-6周)。这个突变体的一个独特特征是 在缺乏NMDA受体介导的活性的情况下，癫痫发作活动就会发生。 许多癫痫动物模型都是基于NMDA活性的上调， 因此，我们的模型可能会提供产生超兴奋性的独特方法 导致癫痫样活动独立于NMDA活动。初步 结果提示NMDA受体在神经元调节中起着重要作用 在正常发育过程中的兴奋性；然而， 这些小鼠选择性缺乏NMDA受体会导致过度兴奋和 最终，自发性癫痫发作是未知的。建议的目标是 实验是为了调查在发育过程中NMDA受体的缺乏 导致神经元兴奋性改变，以及这是如何引起癫痫的 活动。我们将使用包括分子在内的多学科方法 生物学、遗传学、解剖学、细胞和系统神经生理学，以及 用行为学技术来了解癫痫的发生发展 独特的动物模型。我们计划扩展我们对自发性的描述 用以下具体目的来验证我们的假说：1.癫痫表型。 以确定在发育过程中癫痫易感性是否以及何时发生 化学惊厥剂在突变小鼠中发生了变化。这些结果将提供 大脑皮层内过度兴奋性发展的时间线。2. 绘制出参与癫痫发生和产生的神经网络 突变小鼠通过研究即刻早期基因c-fos的表达。 3.要确定抑制和兴奋之间的平衡是如何改变的 突变的小鼠。我们假设对中间神经元的兴奋性驱动是 在正常动物和这些突变小鼠中，NMDA受体的作用是主导的 NMDA介导的行为的减少导致了体内的全面去抑制 新皮质最终导致癫痫样活动。理解 NMDA受体缺乏如何导致神经元的异常兴奋性 可能会有潜在的临床影响，因为这些结果可能会提供 对人类癫痫患者更好治疗的发展的洞察和 预防癫痫的发展和发生的干预措施。

DESCRIPTION (provided by applicant): Genetic susceptibility has been implicated in more than 40-50% of human epilepsies. However to date, only 12 genes have been associated with human epilepsy syndromes, and these can only account for less than 1% of epilepsy patients. Further identification of genes that are related to the pathogenesis of epilepsy is crucial to understand how epilepsies develop and could eventually lead to better treatment and prevention of the disease. We have generated a unique mutant animal model in which NMDA glutamate receptors are selectively knocked out in the cerebral cortex and hippocampus. Unlike standard NMDA knockout mutant mice that die soon after birth, our mutant mice survive many weeks but they develop seizure activity during late adolescence (3-6 weeks postnatal). A unique feature of this mutant is that this seizure activity develops in the absence of NMDA receptor mediated activity. Many animal models of epilepsy are based on an upregulation of NMDA activity, and thus our model may provide unique means of producing hyperexcitability leading to epileptiform activity independent of NMDA activity. Preliminary results suggest an important role of NMDA receptors in regulating the neuronal excitability during normal development; however, the mechanisms by which the selective lack of NMDA receptors in these mice leads to hyperexcitability and eventually spontaneous seizures is unknown. The goal of the proposed experiments is to investigate how the lack of NMDA receptors during development leads to altered neuronal excitability, and how this gives rise to seizure activity. We will use a multidisciplinary approach including molecular biological, genetic, anatomical, cellular and system neurophysiological, and behavioral techniques to understand the development of epileptogenesis in this unique animal model. We plan to extend our characterization of the spontaneous seizure phenotype to test our hypothesis with the following specific aims: 1. To determine whether and when during development seizure susceptibility to chemical convulsants is altered in the mutant mice. These results would provide a time line for the development of hyperexcitability within the neocortex. 2. To map out neural networks involved in seizure development and generation in the mutant mice by studying the expression of the immediate early gene, c-fos. 3. To determine how the balance between inhibition and excitation is altered in the mutant mice. We hypothesize that the excitatory drive onto interneurons is dominated by NMDA receptor actions in normal animals, and in these mutant mice the reduction of NMDA-mediated actions leads to an overall disinhibition within the neocortex ultimately resulting in epileptiform activity. The understanding of how the lack of NMDA receptors leads to the abnormal excitability in neurons could have potential clinical ramifications in that these results could provide insight for the development of better treatment for human epilepsy patients and interventions to prevent the development and occurrences of seizures.