Identification and reversal of primary and secondary epileptogenic changes

描述(申请人提供)：阐明正常大脑转变为癫痫大脑的基本机制几十年来一直是癫痫研究的圣杯。如果能够了解癫痫发生的机制，那么就可以设计新的治疗方法和疗法来针对这些过程来预防--甚至可能治愈--癫痫。虽然多年来的研究揭示了癫痫发生期间发生的多种变化，但一个基本问题是区分参与癫痫发生的变化与与疾病相关但没有因果关系的变化。这个问题在几乎所有现有的癫痫模型中都很明显，这种模型会导致广泛的脑损伤和细胞变化，从而使疾病的近端原因难以确定。在目前的提案中，我们利用了一种新的癫痫小鼠模型，在这一模型中，癫痫是在有条件地、可诱导地从海马齿状回颗粒细胞(DGC)的一个子集(&gt；5%)中删除mTOR途径抑制物磷酸酶和紧张素同源(PTEN)后发生的。MTOR通路的过度激活与颞叶癫痫的发生有关，而这种缺失的作用--导致新生儿DGC的异常整合--是重要的，因为异常的新生儿DGC是颞叶癫痫的标志性病理，并被怀疑是导致该疾病的原因。我们的研究为DGC异常可导致癫痫提供了直接证据。在证明了DGC异常可能是癫痫的近端原因后，我们现在试图阐明这些细胞促进癫痫发作的机制(S)。我们的指导性假设是，异常的DGC最初通过细胞内在的连接性和活性增加促进癫痫发生，其次通过诱导邻近颗粒细胞及其下游靶点的变化来促进癫痫的发生。为了验证这一假设，我们将确定SA1中异常细胞的主要特征，SA2中原发和继发变化与癫痫发生之间的时间关联，以及这些变化在SA3和SA4中的功能意义。

DESCRIPTION (provided by applicant): Elucidating the basic mechanisms by which a normal brain is transformed into an epileptic brain has been a holy grail of epilepsy research for decades. If the mechanisms of epileptogenesis can be understood, then new treatments and therapies can be designed to target these processes to prevent - and possibly cure - epilepsy. While years of research have revealed a multitude of changes that occur during epileptogenesis, one basic problem has been distinguishing changes that mediate epileptogenesis from changes that are associated with the disease, but play no causal role. This problem is evident for almost all existing models of epilepsy, which produce widespread brain damage and cellular changes, thereby making the proximal cause of the disease difficult to ascertain. For the present proposal, we make a pivotal advance by utilizing a novel mouse model of epilepsy generated in the first term of this grant, in which epilepsy develops following conditional, inducible deletion of the mTOR pathway inhibitor phosphatase and tensin homologue (PTEN) from a subset (>5%) of hippocampal dentate granule cells (DGC). Excessive activation of the mTOR pathway is implicated in the development of temporal lobe epilepsy, and the effect of this deletion - to induce the abnormal integration of newborn DGC - is important because abnormal newborn DGC are a hallmark pathology of temporal lobe epilepsy, and are suspected of causing the disease. Our study provides direct evidence that abnormal DGC can cause epilepsy. Having demonstrating that abnormal DGC can be a proximal cause of epilepsy, we now seek to elucidate the mechanism(s) by which these cells promote seizures. Our guiding hypothesis is that abnormal DGCs promote epileptogenesis initially through cell-intrinsic increases in connectivity and activity, and secondarily by inducing changes among neighboring granule cells and their downstream targets. To test this hypothesis, we will determine the primary features of abnormal cells in SA1, the temporal associations between primary and secondary changes and epileptogenesis in SA2, and the functional significance of these changes in SA3 and 4.