不同类型脑皮层发育不良致难治性癫痫的分子基础

Cortical dysplasia(CD) is the main reason of the intractable epilepsy.The recent research uncovered that the excitablity abnormally increased and excitatory neurons discharge was out of control in the CD neural networks. The key reason of the abnormal excitability increase of CD is the dysfunction of GABA neurons.we found that different types of CD has different excited threshold, abnormal shape positive neurons around the PV and neuron dendritic granular material is different. In this project we will enlarge the amount of specimen, making accurate localization of CD and its adjacent tissue. use the human CD cortex from the resection tissue from epilepsy operation to study the basic mechnism of GABA neurons dysfunction in different CD by the means of electrophysiology, immunohistochemisty, and morphology. The principle contents of this research is as follows:(1) to record and analysis the discharge frequency of GABA neurons, and detect whether the impulse-genic ability of GABA neurons is intact. (2) to analysis the frequence and amplitude of spontaneous excitatory and inhibitory post-synaptic discharge in GABA neurons, and detect whether the ability to drive the GABA neurons is decreased.(3) to detect whether the expression of the Kv3 family on the surface of GABA neurons, and the variation of the content of GABA-A receptor and GABA-B receptor in CD cortex. This study will reinforce our understanding of the principle mechnism of epilepsy genesis in different CD, and then provide the theory base for the treatment of this disease.

癫痫是中枢神经系统的常见病，大脑皮层发育不良(Cortical Dysplasia, CD)是引起难治性癫痫的一个主要原因。研究证明CD组织中GABA神经元功能减弱导致CD神经网络兴奋性异常升高。本人前一个国基金研究发现：不同类型CD组织兴奋阈值不同，形态异常神经元周围PV阳性的颗粒状物质和神经元树突围绕情况不同。本项目将扩大样本量，结合电生理、形态学、免疫组化等方法精确区分CD和CD旁组织，分类研究CD中GABA能神经元功能减弱的基础：(1)记录和分析GABA能神经元放电频率，检测其产生冲动的能力是否受损；(2)分析GABA能神经元上自发兴奋性和抑制性突触后电流的幅度与频率，检测驱使该神经元兴奋的动力是否降低；(3)通过双细胞记录，测定GABA能神经元细胞膜上Kv3家族钾通道表达是否减少,以及CD组织中GABA-A和GABA-B受体表达含量的变化，为更有效治疗该疾病提供理论基础。

大脑皮质发育不良(Cortical Dysplasia, CD)是引起难治性癫痫的一个主要原因。其分子机制尚不清楚，以往研究发现：锥体神经元与GABA能中间神经元的功能失常，可引起大脑皮质内兴奋性与抑制性平衡紊乱，进而引起癫痫发作。另外在局灶性脑皮质发育不良(focal cortical dysplasia，FCD)动物模型上发现GABA能中间神经元的兴奋性相对减低；锥体神经元的抑制性突触后电流(inhibitory postsynaptic currents,IPSC)振幅和频率均较正常组织减少，兴奋性突触后电流(excitatory postsynaptic currents,EPSC)增多。这样的改变可能是FCD异常电活动的关键。本项目依托手术室-实验室高效对接，建立了稳定成熟的人体脑皮质薄片取材流程，结合临床、电生理结果将脑片分为发作起始区(seizure-onsetzone,SOZ)、非SOZ区（non-SOZ）以及内侧颞叶癫痫相对正常的颞叶新皮质区（TLE），应用膜片钳技术分别检测三类脑片中GABA能中间神经元功能、锥体神经元的电生理改变，研究其自发及诱发动作电位。结果发现：（1）在FCD致痫区的发作起始区内，中间神经元自发性EPSC和自发性IPSC平均频率均显著低于non-SOZ，以及内侧颞叶癫痫相对正常的颞叶新皮质。（2）在FCD致痫区的发作起始区内，锥体神经元的自发性IPSC均显著低于non-SOZ与相对正常的颞叶新皮质；而锥体神经元自发性EPSC平均频率在SOZ组显著高于其余两组。（3）SOZ内中间神经元与周围锥体神经元的突触联系相对减少，并且中间神经元兴奋性驱动力相对减低。（4）SOZ内中间神经元和锥体神经元对GABA受体的敏感度减低。该项目研究结果发表了3篇SCI论文，统计源核心期刊论文3篇，综述2篇；培养1名博士研究生及2名硕士研究生，三次在美国癫痫学会（AES）年会上展示部分研究结果。