CRH起搏MCD微灶痫性放电的作用和机制研究

Malformation of cortical dysplasia (MCD) is mainly cause of intractable epilepsy. Existing evidence indicated that there has exciting PGA (pacemaker γ-aminobutyric acid receptor-mediated synaptic activity) current mediated by immature neuron in micro foci of MCD. PGA current of immature neuron, which showed excitatory but not inhibitory activity in adult, could exert pace-making and synchronizing effect on the epileptic discharge of MCD. However, the mechanism of PGA in MCD is unknown. Previous studies found that Corticotropin-Releasing Hormone (CRH) would induce secretion of GABA. As we know, the specific epileptogenesis of CRH have been demonstrated in only immature brain. Moreover, our lab previously observed that CRH is highly associated with generation of PGA in micro foci of MCD. So we speculated that CRH may induce generation of PGA in immature neurons and then cause epileptic discharge in micro foci of MCD. To address these concerns, in the present project, by using the MCD animal models and surgery specimens, we will investigate the expression and distribution of CRH in micro foci of MCD. Combination of culture of immature neurons, we will investigate the role of CRH in GABA secretion of immature neurons and how this process influence on PGA generation. Cre/Loxp transgenic system for conditional CRH expression in immature neuron will be used to test the hypothesis that CRH induce PGA generation and epileptic discharge. Moreover, the detail mechanism of CRH will be explored in this project. Our results will interpret the role of CRH in the PGA generation and epileptic discharge, and provide further insights into the pace-making mechanism of immature neuron and micro epileptic foci of MCD.

皮质发育障碍（MCD）是难治性癫痫的重要病因。已有证据显示，MCD微灶内存在由未成熟神经元介导的兴奋性GABA起搏电流（PGA）,PGA起搏并同步化MCD微灶的痫性放电，但其产生机制不清。既往研究发现促肾上腺皮质激素释放激素（CRH）可诱导GABA的分泌，结合CRH作用于未成熟脑的特点，以及预实验中发现MCD微灶中CRH与未成熟神经元PGA高度相关现象，我们认为CRH通过诱导未成熟神经元PGA而起搏MCD微灶痫性放电。本项目拟利用MCD动物模型和手术切除标本，结合Cre/Loxp转基因系统建立CRH条件性表达动物模型，在CRH形态学和功能学检测基础上，通过离体未成熟神经元培养、在体膜片钳检测等手段了解CRH对微灶未成熟神经元GABA分泌和功能的影响，研究其对微灶未成熟神经元PGA的作用，深入探讨CRH诱导PGA产生的机制，为阐释MCD起搏神经元和微灶痫性起搏机制提供证据。

皮质发育障碍（MCD）是难治性癫痫的重要病因。已有证据显示，MCD微灶内存在由未成熟神经元介导的兴奋性GABA起搏电流（PGA）, PGA起搏并同步化MCD微灶的痫性放电，但其产生机制不清。既往研究发现促肾上腺皮质激素释放激素（CRH）可诱导GABA的分泌，结合CRH作用于未成熟脑的特点，以及预实验中发现MCD微灶中CRH与未成熟神经元PGA高度相关现象，我们认为CRH通过诱导未成熟神经元PGA而起搏MCD微灶痫性放电。本项目利用MCD动物模型和手术切除标本，在CRH形态学和功能学检测基础上，通过离体未成熟神经元培养、在体膜片钳检测等手段了解CRH对微灶未成熟神经元GABA分泌和功能的影响，研究其对微灶未成熟神经元PGA的作用，深入探讨CRH诱导PGA产生的机制。研究结果发现CRH及其下游信号异常表达于MCD微灶，尤其是未成熟神经元内，与癫痫发作密切相关；体外和体内研究显示CRH通过影响GABA的分泌而参与微灶内PGA电流的产生；除影响GABA分泌外，CRH尚通过雌激素β受体作用于突触重塑环节及通过GLUL影响GABA信号而参与CRH的分子机制，而雌激素快速作用受体GPR30则通过炎症作用途径而参与CRH的作用。上述结果为阐释MCD起搏神经元和微灶痫性起搏机制提供证据，并为癫痫的治疗提供新的潜在靶点。