GABA Receptors and Hilar Neuron Survival in Epilepsy

项目摘要 齿状回门区神经元的丢失是最一致的形态学发现之一 人类颞叶癫痫和获得性癫痫的相关模型。肺门的两大类群 神经元经常受损，GABA能生长抑素中间神经元和谷氨酸能苔藓细胞。 尽管多年来人们对肺门神经元很感兴趣，但重要的问题仍然存在。为什么神经元如此容易受到 兴奋性毒性损伤？他们怎么能受到保护？损失和损失的功能影响是什么？ 保存这些神经元的亚群？一系列新技术、试剂和鼠标现在将允许 以令人兴奋的新方式探索这些问题。拟议的研究将使用带有Cre重组酶的小鼠 通过Cre激活的病毒基因表达选择性地操纵这些神经元的表达。一个 光镜和电子显微镜免疫组织化学方法相结合的方法将评估 变化，功能相关性将用电生理学方法确定。总体目标是 为了确定增加这些神经元的紧张性GABA能抑制是否可以起到神经保护作用，在 单独的一组研究，以绘制操作任一苔藓后激活的功能电路 正常和癫痫易感动物体内的细胞或生长抑素神经元。《特定目标1》将测试 假设两组肺门神经元都缺乏GABAA受体？亚单位的实质性表达 (GABAAR)，并有低水平的紧张性抑制。《特定目标2》将检验这样一种假设：表达一个 外源性GABAAR亚基，通常参与小脑的紧张性抑制，将导致 在两组肺门神经元中形成功能性GABAA受体并增加紧张性抑制。特定的 目标3将验证这一假设，即增加对肺门神经元的紧张性抑制将保护它们免受损害。 紧随癫痫持续状态。特定目标4将在活体内检查肺门神经元的功能电路 光遗传学方法选择性操纵神经元，然后通过Fos识别激活的神经元 贴标签。将比较正常动物和癫痫易发动物的激活模式，以测试 刺激体内残留的苔藓细胞或沉默残留的生长抑素中间神经元的假设将 导致癫痫小鼠颗粒细胞活化增加。通过允许选择性地操纵肺门 在完整的大脑中，这些研究将提供它们在正常和改变中的功能的独特观点 神经回路。

Project Summary Loss of neurons in the hilus of the dentate gyrus is one of the most consistent morphological findings in humans with temporal lobe epilepsy and related models of acquired epilepsy. Two major groups of hilar neurons are frequently damaged, GABAergic somatostatin interneurons and glutamatergic mossy cells. Despite years of interest in hilar neurons, important questions persist. Why are the neurons so vulnerable to excitotoxic damage? How could they be protected? What are the functional effects of both loss and preservation of subgroups of these neurons? A set of new technologies, reagents and mice will now allow probing these questions in exciting new ways. The proposed studies will use mice with Cre-recombinase expression in these neurons to selectively manipulate them through Cre-activated viral gene expression. A combination of light and electron microscopic immunohistochemical methods will be used to evaluate the changes, and functional correlates will be determined with electrophysiological methods. The broad goals are to determine if increasing tonic GABAergic inhibition in these neurons could be neuroprotective and, in a separate set of studies, to map the functional circuits that are activated following manipulation of either mossy cells or somatostatin neurons in normal and seizure-prone animals in vivo. Specific Aim 1 will test the hypothesis that both groups of hilar neurons lack substantial expression of the ¿ subunit of the GABAA receptor (GABAAR) and have low levels of tonic inhibition. Specific Aim 2 will test the hypothesis that expressing an exogenous GABAAR subunit, which is normally involved in tonic inhibition in the cerebellum, will lead to the formation of functional GABAA receptors and increase tonic inhibition in both groups of hilar neurons. Specific Aim 3 will test the hypothesis that increasing tonic inhibition in hilar neurons will protect them from damage following status epilepticus. Specific Aim 4 will examine the functional circuitry of hilar neurons in vivo by using optogenetic methods to manipulate the neurons selectively and then identifying the activated neurons by Fos labeling. The patterns of activation in normal and seizure-prone animals will be compared to test the hypotheses that stimulating remaining mossy cells or silencing remaining somatostatin interneurons in vivo will lead to increased granule cell activation in the epileptic mice. By allowing selective manipulation of hilar neurons in the intact brain, these studies will provide unique views of their function within normal and altered neuronal circuits.