Identification and reversal of primary and secondary epileptogenic changes

项目摘要/摘要 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。如果能够理解癫痫发生的机制， 然后，可以设计新的治疗方法和疗法，以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过程中发生的多种变化，但其中一个 基本的问题一直是区分参与癫痫发生的变化和与之相关的变化 与疾病有关，但没有起到因果作用。这个问题在几乎所有现有的癫痫模型中都很明显， 这会导致广泛的脑损伤和细胞变化，从而使 疾病很难确定。在目前的建议中，我们利用了一种新的癫痫小鼠模型，该模型产生于 这项赠与的第一个期限，在此期间，自发性皮质癫痫的发生是有条件的、可诱发的 MTOR途径抑制物磷酸酶和紧张素同源物(PTEN)在9%的海马区缺失 齿状颗粒细胞。这种缺失对诱导新生颗粒细胞异常整合的作用 -很重要，因为异常的新生颗粒细胞是颞叶癫痫的标志性病理， 并被怀疑是导致这种疾病的原因。我们的模型提供了直接证据表明异常颗粒细胞可以 导致癫痫，并创造了一个机会，了解它们是如何导致疾病的。 这一模型的研究使我们假设，在颞叶癫痫中，自发性癫痫发作 由固有的过度兴奋的颗粒细胞和抑制控制受损的联合作用所致 这些细胞。为了测试这个两次致痫的模型，我们将充分利用我们的 PTEN基因敲除模型：控制异常颗粒细胞数量或“负载”的能力。我们会 产生5-8%的颗粒细胞缺乏PTEN的动物。这些动物表现出异常的海马体 生理上的，但不是明显的大脑皮层癫痫。这构成了第一个“重击”。然后我们将挑战这些被更改的 通过在体外和体内沉默不同类别的海马区抑制性中间神经元的电路-第二次打击。 我们预测，去抑制作用将与PTEN基因敲除颗粒细胞协同作用，破坏细胞的稳定 海马环路和促进癫痫发作。这些研究将提供一个概念验证测试，以确定时间 叶癫痫的发展，并将提供治疗策略的洞察力。

Project Summary/Abstract 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 utilize a novel mouse model of epilepsy generated in the first term of this grant, in which spontaneous cortical seizures develop following conditional, inducible deletion of the mTOR pathway inhibitor phosphatase and tensin homologue (PTEN) from >9% of hippocampal dentate granule cells. The effect of this deletion – to induce the abnormal integration of newborn granule cells – is important because abnormal newborn granule cells are a hallmark pathology of temporal lobe epilepsy, and are suspected of causing the disease. Our model provides direct evidence that abnormal granule cells can cause epilepsy, and creates an opportunity to understand how they cause the disease. Work with this model has led us to hypothesize that spontaneous seizures in temporal lobe epilepsy result from the combinatorial effects of intrinsically hyperexcitable granule cells and impaired inhibitory control of these cells. To test this two-hit model of epileptogenesis, we will make full use of a unique feature of our PTEN knockout model: the ability to manipulate the number or “load” of abnormal granule cells. We will generate animals in which 5-8% of granule cells lack PTEN. These animals exhibit abnormal hippocampal physiology, but not overt cortical seizures. This constitutes the first “hit”. We will then challenge these altered circuits by silencing distinct classes of hippocampal inhibitory interneurons in vitro and in vivo – the second hit. We predict that disinhibition will act synergistically with PTEN knockout granule cells to destabilize the hippocampal circuit and promote seizures. The studies will provide a proof-of-concept test for how temporal lobe epilepsy develops, and will provide insights into therapeutic strategies.