遗传性癫痫大鼠海马内电压门控性钠离子通道四种亚型的表达及分布

目的探讨遗传性癫痫大鼠(Tremor rat,TRM)大脑海马中,电压门控性钠离子通道Ⅰ、Ⅱ、Ⅲ、Ⅳ亚型(Na_v1.1、Na_v1.2、Na_v1.3与Na_v1.6)的表达及分布。方法 Western blot检测TRM(n=7)和Wistar大鼠(n=7)海马中Na_v1.1、Na_v1.2、Na_v1.3与Na_v1.6的蛋白表达情况。免疫荧光法进一步分析TRM及Wistar大鼠海马CAI、CA3和DG区中这四种亚型的分布与定位。结果相较于正常大鼠,TRM海马中Na_v1.1、Na_v1.2、Na_v1.3与Na_v1.6蛋白表达均明显上调(P0.01)。此外,这四种VGSC亚型在TRM海马CAI,CA3区神经元及DG区颗粒细胞中分布广泛,且主要定位在细胞膜上。结论 Na_v1.1、Na_v1.2、Na_v1.3与Na_v1.6在TRM大鼠海马中出现显著高表达,可能与遗传性癫痫发生机制有关。     

癫痫与电压依赖性钠离子通道的分子遗传学进展

癫痫是一类抽搐相关性神经系统疾病,其发病机制复杂,临床治疗困难,严重影响人类的健康。随着分子遗传学和药理学的发展,癫痫的发病机制也取得了很大的进展。大量的研究表明,电压依赖性离子通道在癫痫的发病中发挥着重要的作用。现从分子水平对电压依赖性钠离子通道与癫痫的相关性及其亚基的相互作用方面进行综述。     

背根神经节电压门控钠离子通道与神经性疼痛的研究进展

神经性疼痛属于慢性疼痛,以痛觉过敏为特征,表现为自发性持续或间歇性烧灼痛,同时对疼痛刺激的反应性增高.由于发病机制尚不清楚,一直以来是困扰医学界的难题.背根神经节(DRG)作为痛觉传入的第一级神经元在痛觉的外周机制中起着极为重要的作用,对背根神经节上离子通道的认识,对于阐明神经性疼痛的机制有重要意义.本文结合近年来对背根节上电压门控钠通道的研究进展,对其与神经性疼痛的关系加以综述,望有助于同行了解相关领域的最新研究动态.     

电压-门控Na+通道基因突变与癫痫

电压-门控Na+通道和癫痫的关系十分密切，许多癫痫综合征的发生已被证明是由Na+通道基因突变引起，且编码α和/或β亚单位的基因发生突变均可以引起癫痫。基因突变后产生的异常Na+通道蛋白引起癫痫的发病机制仍不明确。基因和细胞治疗为治疗离子通道基因突变引起的癫痫提供了新的思路。     

癫痫与电压依赖性钠通道的分子遗传学进展

癫痫是一类抽搐相关性神经系统疾病，其发病机制复杂，临床治疗困难，严重影响人类的健康。随着分子遗传学和药理学的发展，癫痫的发病机制也取得了很大的进展。大量的研究表明，电压依赖性离子通道在癫痫的发病中发挥着重要的作用。本文从分子水平对电压依赖性钠离子通道与癫痫的相关性及其亚基的相互作用方面进行综述。     

电压门控钠离子通道的分子生物学研究进展

电压门控钠离子通道由α亚基和β亚基组成，α亚基由四个对称的同源功能区组成，每一功能区都含有六个α螺旋膜片段（Ｓ１－Ｓ６），Ｓ５和Ｓ６间尚有二短的片段（ＳＳ１和ＳＳ２）；β１亚基为含有一个α螺旋片段和一个细胞内功能区的蛋白质。它的电压依赖性激活、失活、选择性通透、受体位点都与其结构有密切关系。     

钠离子通道基因SCN1A、SCN2A、SCN1B突变与癫痫

癫痫是一种常见神经系统慢性疾病,是由脑部神经元过度同步化放电所导致.目前发现多种编码电压门控性钠离子通道的基因突变与癫痫的发生有关.其中大多数突变是在编码钠离子通道α亚基的基因SCN1A、SCN2A和编码β亚基的基因SCN1B上发现的.不同的基因突变导致的癫痫综合征表型轻重不一.轻者表现为热性惊厥,预后良好,重者可表现为顽固性癫痫.钠离子通道基因突变引起的常见癫痫综合征有全面性癫痫伴热性惊厥附加症(generalized epilepsy with febrile seizure plus,GEFS+)、婴儿严重肌阵挛癫痫(severe myoclonic epilepsy of infancy,SMEI)、良性家族性新生儿-婴儿惊厥(benign familial neonatal-infantile seizure,BFNIS)等.本文就SCN1A、SCN2A和SCN1B基因突变导致的癫痫综合征的临床表型及其基因突变特点作一综述.     

CaV 2.3 电压门控性钙通道与癫痫

癫痫是神经系统疾病中较为常见的疾病之一,由大量神经元反复发作的异常放电[1]而引起的中枢神经系统短暂性功能失常为特征.癫痫的发病机制非常复杂,包括Ca2+内流引发的细胞毒性;苔藓纤维芽生假说;谷氨酸和γ-氨基丁酸及其受体结构和功能异常;氧化应激损伤等.     

电压门控氯通道生物学功能与疾病的关系

电压门控氯通道是表达于细胞膜或细胞器质膜上的一类阴离子跨膜通道蛋白,具有调节细胞容积、参与细胞迁移、增殖与凋亡以及氧化应激等生物学功能,本综述总结近年来该通道生物学功能及其与疾病的相关研究进展。     

电压门控钠离子通道Na_v1.1与癫痫

癫痫的发生与电压门控钠通道基因突变密切相关,涉及到电压门控性钠通道亚型以NaV1.1亚型的基因突变最为重要。编码电压门控钠离子通道NaV1.1亚型的SCN1A基因突变可改变钠离子通道电生理功能,如电流-电压曲线的移动、电流幅度增加、失活减慢等,使得神经元的兴奋性增加,造成神经元发生高频高幅的异常放电波,进而导致遗传性癫痫伴热性惊厥附加症、Dravet综合征、颞叶癫痫等多种癫痫病理类型。     

Generalized epilepsy with febrile seizures plus-associated sodium channel beta1 subunit mutations severely reduce beta subunit-mediated modulation of sodium channel function

Two novel mutations (R85C and R85H) on the extracellular immunoglobulin-like domain of the sodium channel beta1 subunit have been identified in individuals from two families with generalized epilepsy with febrile seizures plus (GEFS+). The functional consequences of these two mutations were determined by co-expression of the human brain NaV1.2 alpha subunit with wild type or mutant beta1 subunits in human embryonic kidney (HEK)-293T cells. Patch clamp studies confirmed the regulatory role of beta1 in that relative to NaV1.2 alone the NaV1.2+beta1 currents had right-shifted voltage dependence of activation, fast and slow inactivation and reduced use dependence. In addition, the NaV1.2+beta1 current entered fast inactivation slightly faster than NaV1.2 channels alone. The beta1(R85C) subunit appears to be a complete loss of function in that none of the modulating effects of the wild type beta1 were observed when it was co-expressed with NaV1.2. Interestingly, the beta1(R85H) subunit also failed to modulate fast kinetics, however, it shifted the voltage dependence of steady state slow inactivation in the same way as the wild type beta1 subunit. Immunohistochemical studies revealed cell surface expression of the wild type beta1 subunit and undetectable levels of cell surface expression for both mutants. The functional studies suggest association of the beta1(R85H) subunit with the alpha subunit where its influence is limited to modulating steady state slow inactivation. In summary, the mutant beta1 subunits essentially fail to modulate alpha subunits which could increase neuronal excitability and underlie GEFS+ pathogenesis.     

Developmental exposure to lead causes inherent changes on voltage-gated sodium channels in rat hippocampal CA1 neurons

In this study, the effects of chronic lead (Pb(2+)) exposure, during day 0 of gestation (E0) to postnatal day 15 (P15), on voltage-gated sodium channel currents (I(Na)) were investigated in CA1 field of the hippocampus (CA1) neurons using the conventional whole-cell patch-clamp technique on rat hippocampal slices. We found that developmental lead exposure increased the activation threshold and the voltage at which the maximum I(Na) current was evoked, caused positive shifts of I(Na) steady-state activation curve, and enlarged I(Na) tail-currents; Pb(2+) delayed the activation of I(Na) in a voltage-dependent manner, prolonged the time course of the fast inactivation of sodium channels; Pb(2+) induced a right shift of the steady-state inactivation curve, accelerated the activity-dependent attenuation of I(Na), but made no significant effects on the time course of the recovery of I(Na) from inactivation and the fraction of inactivated channels. In addition, the co-treatment with alpha-tocopherol (VE), an effective antioxidant and free radical scavenger, completely prevented the aforementioned changes on I(Na). The alterations on I(Na) properties induced by developmental lead exposure were partly different from that in previous acute experiments under the conditions closer to physiological situation, and the process was considered related to the participating of lead in lipid peroxidation reaction, which has been reported to change the conformation and biophysical functions of membrane proteins.     

Voltage-gated Na+ channels confer invasive properties on human prostate cancer cells

Prostate cancer is the second leading cause of cancer deaths in American males, resulting in an estimated 37,000 deaths annually, typically the result of metastatic disease. A consequence of the unsuccessful androgen ablation therapy used initially to treat metastatic disease is the emergence of androgen-insensitive prostate cancer, for which there is currently no prescribed therapy. Here, three related human prostate cancer cell lines that serve as a model for this dominant form of prostate cancer metastasis were studied to determine the correlation between voltage-gated sodium channel expression/function and prostate cancer metastatic (invasive) potential: the non-metastatic, androgen-dependent LNCaP LC cell line and two increasingly tumorogenic, androgen-independent daughter cell lines, C4 and C4-2. Fluorometric in vitro invasion assays indicated that C4 and C4-2 cells are more invasive than LC cells. Immunoblot analysis showed that voltage-gated sodium channel expression increases with the invasive potential of the cell line, and this increased invasive potential can be blocked by treatment with the specific voltage-gated sodium channel inhibitor, tetrodotoxin (TTX). These data indicate that increased voltage-gated sodium channel expression and function are necessary for the increased invasive potential of these human prostate cancer cells. When the human adult skeletal muscle sodium channel Na_v1.4 was expressed transiently in each cell line, there was a highly significant increase in the numbers of invading LC, C4, and C4-2 cells. This increased invasive potential was reduced to control levels by treatment with TTX. These data are the first to indicate that the expression of voltage-gated sodium channels alone is sufficient to increase the invasive potential of non-metastatic (LC cells) as well as more aggressive cells (i.e., C4 and C4-2 cells). Together, the data suggest that increased voltage-gated sodium channel expression alone is necessary and sufficient to increase the invasive potential of a set of human prostate cancer cell lines that serve as a model for prostate cancer metastasis.     

Mechanisms of action of ligands of potential-dependent sodium channels

Potential-dependent sodium channels play a leading role in generating action potentials in excitable cells. Sodium channels are the site of action of a variety of modulator ligands. Despite numerous studies, the mechanisms of action of many modulators remain incompletely understood. The main reason that many important questions cannot be resolved is that there is a lack of precise data on the structures of the channels themselves. Structurally, potential-dependent sodium channels are members of the P-loop channel superfamily, which also include potassium and calcium channels and glutamate receptor channels. Crystallization of a series of potassium channels showed that it was possible to analyze the structures of different members of the superfamily using the "homologous modeling" method. The present study addresses model investigations of the actions of ligands of sodium channels, including tetrodotoxin and batrachotoxin, as well as local anesthetics. Comparison of experimental data on sodium channel ligands with x-ray analysis data allowed us to reach a new level of understanding of the mechanisms of channel modulation and to propose a series of experimentally verifiable hypotheses.     

Voltage-gated ion channels in dendrites of hippocampal pyramidal neurons

The properties and distribution of voltage-gated ion channels contribute to electrical signaling in neuronal dendrites. The apical dendrites of CA1 pyramidal neurons in hippocampus express a wide variety of sodium, calcium, potassium, and other voltage-gated channels. In this report, we provide some new evidence for the role of the delayed-rectifier K⁺ channel in shaping the dendritic action potential at different membrane potentials.     

Voltage-gated sodium channel organization in neurons: Protein interactions and trafficking pathways

In neurons, voltage-gated sodium (Nav) channels underlie the generation and propagation of the action potential. The proper targeting and concentration of Nav channels at the axon initial segment (AIS) and at the nodes of Ranvier are therefore vital for neuronal function. In AIS and nodes, Nav channels are part of specific supra-molecular complexes that include accessory proteins, adhesion proteins and cytoskeletal adaptors. Multiple approaches, from biochemical characterization of protein–protein interactions to functional studies using mutant mice, have addressed the mechanisms of Nav channel targeting to AIS and nodes. This review summarizes our current knowledge of both the intrinsic determinants and the role of partner proteins in Nav targeting. A few fundamental trafficking mechanisms, such as selective endocytosis and diffusion/retention, have been characterized. However, a lot of exciting questions are still open, such as the mechanism of differentiated Nav subtype localization and targeting, and the possible interplay between electrogenesis properties and Nav concentration at the AIS and the nodes.     

丙戊酸钠处理对于癫痫大鼠模型海马内细胞自噬的影响

目的:研究丙戊酸钠(VPA)对癫痫模型大鼠海马内细胞自噬、动物脑电图和行为学的影响。方法:制作癫痫大鼠模型并随机分为癫痫组、3甲基腺嘌呤(3MA)组、VPA组及VPA联合3MA组四组,设正常大鼠为对照组。观察各组行为学及脑电图变化,HE及Nissl染色显示神经元的损伤情况,免疫组织化学染色、Western Blot、Real-time PCR检测自噬标记物微管相关蛋白1轻链3(LC3)表达。结果:行为学观察及脑电图检测显示,丙戊酸钠组及丙戊酸钠联合3MA组均可降低癫痫发作等级,3MA组无抗癫痫效果。HE及Nissl染色显示,对照组未见明显异常,癫痫组神经元损伤严重,丙戊酸钠组与癫痫组相比,神经元损伤明显减轻;3MA组与癫痫组相比,神经元损伤明显减轻;丙戊酸钠联合3MA组与丙戊酸钠组相比,神经元损伤明显减轻。免疫组织化学染色、Western Blot、Real-time PCR检测显示,对照组LC3呈低表达,癫痫组LC3表达明显高于对照组;丙戊酸钠组LC3表达明显高于癫痫组;3MA组LC3表达明显低于癫痫组;丙戊酸钠联合3MA组LC3表达明显低于丙戊酸钠组。结论:VPA处理能够诱导癫痫大鼠海马内细胞自噬增加和导致神经元损伤。