细胞凋亡中Ca2+稳态失调机制的研究进展

Ca2+是重要的胞内信号传导因子,其稳态失调是细胞凋亡中的一个普遍现象.Ca2+稳态失调机制涉及胞外Ca2+内流,胞内钙库动员,Ca2+空间分布改变,细胞内活性氧及Bcl-2基因的调节等.研究凋亡过程中Ca2+稳态失调的发生机制,有助于阐明凋亡的启动及信号传导机制,为各种凋亡相关疾病的诊治及药物开发提供新的思路.     

α-黑素细胞刺激素对原代DMNV细胞钙离子通路及凋亡的影响

目的： 以体外培养的大鼠原代迷走神经运动背核（DMNV）细胞为对象,探讨α-黑素细胞刺激素(α-MSH)对原代DMNV细胞钙离子通路及凋亡的影响。方法：采用体外大鼠原代DMNV细胞培养以及［Ca2+］i测量、实时荧光定量PCR、ELISA细胞凋亡实验等方法进行研究。结果：正常大鼠DMNV组织中存在黑素细胞刺激素受体-4（MC4R）mRNA的表达;NDP-MSH激活MC4R可以促进原代DMNV细胞钙离子内流;NDP-MSH可以降低凝血酶（PAR-1,thrombin）和胰蛋白酶（PAR-2,trypsin）对原代DMNV细胞凋亡。结论：α-MSH可以激发原代 DMNV细胞钙离子内流,降低原代DMNV细胞凋亡。     

颞叶癫痫病灶内bax、fas、caspase-3蛋白的表达

目的探讨细胞凋亡调控基因bax、fas、caspase-3在颢叶癫痫患者病灶内的表达及意义。方法应用免疫组化S-P法检测24例颞叶癫痫患者手术切除病灶内凋亡相关基因bax、fas、caspase-3的表达,同时采用光镜、电镜及原位末端标记（TUNEL）方法检测神经细胞凋亡的情况。结果bax蛋白在癫痫组与对照组中均轻微表达,两者间差异无显著性（P〉0.05）;fas蛋白在对照组中无表达,在癫痫组表达明显增强（P〈0．001）;caspase-3在对照组中有轻微表达,在癫痫组表达明显增强（P〈0．01）。光镜检查及TUNEL染色均未发现凋亡的神经细胞,但电镜检查的8例标本中有3例发现少量早期凋亡征象的神经元。结论癫痫患者脑内存在神经元凋亡现象。fas、caspase-3基因在这一过程中可能发挥了重要作用。     

线粒体损伤在创伤弧菌诱导树突状细胞凋亡中的作用

 目的：探讨线粒体损伤在创伤弧菌（Vibrio vulnificus,Vv）诱导树突状细胞（dendritic cell,DC）凋亡过程中的作用及其可能机制。方法：建立Vv 1.1758与DC2.4细胞混合培养模型。采用扫描电镜和透射电镜观察创伤弧菌侵入细胞方式和细胞线粒体病变情况。荧光探针DCFH-DA和Fluo-8/AM分别检测侵入细胞内活性氧（ROS）和Ca2+离子水平。流式细胞术检测细胞线粒体膜电位和细胞凋亡情况。采用Western blotting检测NF-κB p65和TNF-α蛋白的表达。结果：Vv 1.1758可诱导DC2.4细胞凋亡。Vv 1.1758以菌体一端与细胞表面结合的方式侵入细胞,侵入细胞的线粒体有明显病变,细胞内ROS和Ca2+水平升高,线粒体膜电位降低。共培育1 h,NF-κB p65蛋白即开始升高,5 h达高峰,6 h稍有下降;TNF-α蛋白则在共培育2 h开始增高,6 h达高峰。结论：线粒体损伤在Vv诱导DC凋亡中发挥作用,其作用机制可能与细胞内ROS和Ca2+水平升高、线粒体膜电位降低有关,NF-κB p65和TNF-α可能是细胞凋亡过程中的重要信号分子。     

没食子儿茶素没食子酸酯对1-甲基-4-苯基吡啶离子诱导的大鼠PC12细胞凋亡的作用

目的： 探讨没食子儿茶素没食子酸酯(EGCG)抑制1-甲基-4-苯基吡啶离子（MPP+）诱导大鼠PC12细胞凋亡及其抗氧化作用、调节胞浆钙离子稳态与其抑制细胞凋亡作用之间的关系。方法: 培养大鼠肾上腺嗜铬细胞瘤细胞株PC12细胞,给予MPP+诱导细胞凋亡。EGCG（10、50及100 μmol·L-1）预处理0.5 h,再加入MPP+使其终浓度为900 μmol·L-1处理24 h后,MTT法检测细胞存活率,Annexin V-PI双染流式细胞仪检测细胞凋亡,荧光酶标仪测定细胞内活性氧,激光共聚焦荧光显微镜通过检测细胞内钙的荧光强度、检测细胞胞浆［Ca2+］i的变化,透射电镜观察凋亡细胞线粒体结构形态变化,并测定细胞内超氧化物歧化酶（SOD）和丙二醛（MDA）的含量。结果: MPP+呈剂量依赖性损伤PC12细胞,诱导细胞凋亡发生率达到31.0％。与模型组比较,EGCG处理后,明显提高细胞活力,降低凋亡细胞率,同时增强SOD活性、减少MDA和ROS的含量,降低胞浆［Ca2+］i浓度,减轻MPP+诱致的细胞线粒体改变。结论: EGCG具有抑制MPP+诱导的PC12细胞凋亡的作用,其作用机制可能与其提高细胞抗氧化能力和减少胞浆［Ca2+］i有关。     

左卡尼汀通过抑制钙/钙调素依赖蛋白激酶Ⅱ信号通路抑制过氧化氢诱导的大鼠心肌细胞凋亡

 目的： 观察左卡尼汀对过氧化氢（H2O2）诱导的大鼠心肌细胞凋亡的保护作用及其机制。方法：利用200 μmol/L H2O2刺激12 h,建立体外原代培养新生乳鼠心肌细胞凋亡模型。Ca2+螯合剂1,2-双(2-氨基苯氧基)乙烷-N, N, N′, N′-四乙酸(BAPTA)、钙调素依赖蛋白激酶II (CaMKII)特异性抑制剂KN93及左卡尼汀分别于加入H2O2前30 min或1 h加入,以检测这3种药物对H2O2刺激下心肌细胞活力、细胞凋亡、细胞内静息钙浓度（［Ca2+］i）及磷酸化CaMKII (p-CaMKII)表达的影响。利用MTT比色法检测心肌细胞活力;流式细胞仪检测细胞凋亡率;利用激光共聚焦扫描检测［Ca2+］i;蛋白质免疫印迹法检测cleaved caspase-3及p-CaMKII的表达。结果：模型组经200 μmol/L H2O2作用12 h后,细胞活力显著下降,细胞凋亡率显著增加。BAPTA、KN93及左卡尼汀预处理显著抑制上述细胞损伤。进一步研究发现,H2O2 诱导的 ［Ca2+］i水平升高、cleaved caspase-3及p-CaMKII的表达增加均可被上述3种药物不同程度地抑制。结论：左卡尼汀可抑制H2O2所致的心肌细胞凋亡,该心肌保护作用可能与其抑制Ca2+/CaMKⅡ信号通路有关。     

细胞凋亡中的钙调节

胞质Ca2 + 升高是细胞凋亡中Ca2 + 调节的经典模式 ,但近年来有证据表明胞质Ca2 + 下降同样能诱导细胞凋亡。目前研究发现 ,胞内Ca2 + 在细胞质、细胞核以及细胞钙库线粒体和内质网的动态平衡破坏和重新分布直接参与细胞凋亡信号的调控 ,而Bcl 2家族蛋白在细胞凋亡过程的胞内Ca2 + 调节及继后的一系列生理效应中发挥特殊作用。细胞凋亡中Ca2 + 调节的深入研究不但有助于阐明细胞凋亡的调控机理 ,同时为相关疾病防治和药物开发提供新的策略     

钙离子对重组创伤弧菌溶细胞素诱导THP-1细胞损伤的影响机制

目的 研究重组创伤弧菌溶细胞素( rVvhA)诱导人单核细胞白血病细胞(THP-1)的凋亡机制及其Ca2+的变化.方法 采用CCK-8法、激光共聚焦显微镜结合Fluo 3/AM法、流式细胞术结合AnnexinV -PI标记等检测rVvhA对THP-1细胞的影响,并观察胞内Ca2+浓度变化.结 果rVvhA可诱导THP-1细胞发生凋亡并引起细胞内Ca2+浓度升高,细胞内钙离子螯合剂BAPTA-AM处理组胞内钙离子升高幅度远高于细胞外钙离子螯合剂EGTA处理组.结论 rVvhA具有诱导THP-1细胞凋亡的生物学活性,并能引起细胞内Ca2+浓度升高,升高的Ca2+主要源于胞外钙离子内流.     

离子霉素对SW480和SWO-38细胞中E-cadherin裂解的影响

 目的：观察可促进钙离子内流的工具药离子霉素(ionomycin),对不同肿瘤细胞株SW480及SWO-38其C末端片段2（E-cad/CTF2）的表达裂解的影响。方法：应用MTT法确定ionomycin作用于 SW480及SWO-38细胞的最佳浓度;Western blotting检测ionomycin 作用不同时间后E-cadherin全长及其C末端片段2(E-cad/CTF2)的表达水平;共聚焦显微镜动态检测SWO-38细胞胞内Ca2+浓度变化。结果：Ionomycin对SW480及SWO-38细胞均有细胞毒性作用,半数抑制浓度均为12 μmol/L,ionomycin可促进 SW480细胞中Ca2+浓度增加,E-cadherin裂解,E-Cad/CTF2片段水平升高,ionomycin没有引起SWO-38细胞中的大量钙内流,对E-cadherin裂解没有明显作用。结论：Ionomycin可促进钙离子内流,引起SW480肿瘤细胞E-cadherin裂解,但对SWO-38细胞E-cadherin裂解无明显影响。     

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.     

Aberrant neuronal physiology in the basal nucleus of the amygdala in a model of chronic limbic epilepsy

Limbic epilepsy is a chronic condition associated with a broad zone of seizure onset and pathology. Studies have focused mainly on the hippocampus, but there are indications that changes occur in other regions of the limbic system. This study used in vitro intracellular recording and histology to examine alterations to the physiology and anatomy of the basal nucleus of the amygdala in a rat model of chronic limbic epilepsy characterized by spontaneously recurring seizures. Epileptic pyramidal neuron responses evoked by stria terminalis stimulation revealed hyperexcitability characterized by multiple action potential bursts and no evident inhibitory potentials. In contrast, no hyperexcitability was observed in amygdalar neurons from kindled (included as a control for seizure activity) or control rats. Blockade of ionotropic glutamate receptors unmasked inhibitory postsynaptic potentials in epileptic pyramidal neurons. Control, kindled and epileptic inhibitory potentials were predominantly biphasic, with fast and slow components, but a few cells exhibited only the fast component (2/12 in controls, 0/3 in kindled, 3/10 in epileptic). Epileptic fast inhibitory potentials had a more rapid onset and shorter duration than control and kindled. Approximately 40% of control neurons exhibited spontaneous inhibitory potentials; no spontaneous inhibitory potentials were observed in neurons from kindled or epileptic rats. A preliminary histological examination revealed no gross alterations in the basal amygdala from epileptic animals.These results extend previous findings from this laboratory that hyperexcitability is found in multiple epileptic limbic regions and may be secondary to multiple alterations in excitatory and inhibitory efficacy. Because there were no differences between control and kindled animals, the changes observed in the epileptic animals are unlikely to be secondary to recurrent seizures.     

THE ROLE OF THE PIRIFORM CORTEX IN KINDLING

In epilepsy research, there is growing interest in the role of the piriform cortex (PC) in the development and maintenance of limbic kindling and other types of limbic epileptogenesis leading to complex partial seizures, i.e. the most common type of seizures in human epilepsy. The PC (“primary olfactory cortex”) is the largest area of the mammalian olfactory cortex and receives direct projections from the olfactory bulb via the lateral olfactory tract (LOT). Beside the obvious involvement in olfactory perception and discrimination, the PC, because of its unique intrinsic associative fiber system and its various connections to and from other limbic nuclei, has been implicated in the study of memory processing, spread of excitatory waves, and in the study of brain disorders such as epilepsy with particular emphasis on the kindling model of temporal lobe epilepsy with complex partial seizures. The interest in the kindling model is based primarily on the following observations. (1) the PC contains the most susceptible neural circuits of all forebrain regions for electrical (or chemical) induction of limbic seizures. (2) During electrical stimulation of other limbic brain regions, broad and large afterdischarges can be observed in the ipsilateral PC, indicating that the PC is activated early during the kindling process. (3) The interictal discharge, which many consider to be the hallmark of epilepsy, originates in the PC, independent of which structure serves as the kindled focus. (4) Autoradiographic studies of cerebral metabolism in rat amygdala kindling show that, during focal seizures, the area which exhibits the most consistent increase in glucose utilization is the ipsilateral paleocortex, particularly the PC. (5) During the commonly short initial afterdischarges induced by stimulation of the amygdala at the early stages of kindling, the PC is the first region that exhibits induction of immediate-early genes, such as c-fos. (6) The PC is the most sensitive brain structure to brain damage by continuous or frequent stimulation of the amygdala or hippocampus. (7) Amygdala kindling leads to a circumscribed loss of GABAergic neurons in the ipsilateral PC, which is likely to explain the increase in excitability of PC pyramidal neurons during kindling. (8) Kindling of the amygdala or hippocampus induces astrogliosis in the PC, indicating neuronal death in this brain region. Furthermore, activation of microglia is seen in the PC after amygdala kindling. (9) Complete bilateral lesions of the PC block the generalization of seizures upon kindling from the hippocampus or olfactory bulb. Incomplete or unilateral lesions are less effective in this regard, but large unilateral lesions of the PC and adjacent endopiriform nucleus markedly increase the threshold for induction of focal seizures from stimulation of the basolateral amygdala (BLA) prior to and after kindling, indicating that the PC critically contributes to regulation of excitability in the amygdala. (10) Potentiation of GABAergic neurotransmission in the PC markedly increases the threshold for induction of kindled seizures via stimulation of the BLA, again indicating a critical role of the PC in regulation of seizure susceptibility of the amygdala. Microinjections of NMDA antagonists or sodium channel blockers into the PC block seizure generalization during kindling development. (11) Neurophysiological studies on the amygdala-PC slice preparation from kindled rats showed that kindling of the amygdala induces long-lasting changes in synaptic efficacy in the ipsilateral PC, including spontaneous discharges and enhanced susceptibility to evoked burst responses. The epileptiform potentials in PC slice preparations from kindled rats seem to originate in neurons at the deep boundary of PC. Spontaneous firing and enhanced excitability of PC neurons in response to kindling from other sites is also seen in vivo, substantiating the fact that kindling induces long-lasting changes in the PC comparable to abnormalities seen in primary foci. Taken together, these observations indicate that the PC might be part of an epileptic network which is pivotal in the genesis of kindling, facilitating and intensifying the spread of seizures from a focus in amygdala or hippocampus to cortical and subcortical regions along pathways that also are utilized in normal movements. Although direct evidence implicating the PC in the pathogenesis of human epilepsy is not yet available, the experimental data reviewed in this paper should initiate clinical studies on the potential role of this brain structure as a pacemaker or secondary focus in TLE and other types of epilepsy. Copyright © 1996 Elsevier Science Ltd.     

Dynamic seizure-related changes in extracellular signal-regulated kinase activation in a mouse model of temporal lobe epilepsy

Extracellular signal-regulated kinase (ERK) is highly sensitive to regulation by neuronal activity and is critically involved in several forms of synaptic plasticity. These features suggested that alterations in ERK signaling might occur in epilepsy. Previous studies have described increased ERK phosphorylation immediately after the induction of severe seizures, but patterns of ERK activation in epileptic animals during the chronic period have not been determined. Thus, the localization and abundance of phosphorylated extracellular signal-regulated kinase (pERK) were examined in a pilocarpine model of recurrent seizures in C57BL/6 mice during the seizure-free period and at short intervals after spontaneous seizures. Immunolabeling of pERK in control animals revealed an abundance of distinctly-labeled neurons within the hippocampal formation. However, in pilocarpine-treated mice during the seizure-free period, the numbers of pERK-labeled neurons were substantially decreased throughout much of the hippocampal formation. Double labeling with a general neuronal marker suggested that the decrease in pERK-labeled neurons was not due primarily to cell loss. The decreased ERK phosphorylation in seizure-prone animals was interpreted as a compensatory response to increased neuronal excitability within the network. Nevertheless, striking increases in pERK labeling occurred at the time of spontaneous seizures and were evident in large populations of neurons at very short intervals (as early as 2 min) after detection of a behavioral seizure. These findings suggest that increased pERK labeling could be one of the earliest immunohistochemical indicators of neurons that are activated at the time of a spontaneous seizure.     

Clinicopathological findings in patients who have undergone epilepsy surgery in the first year of life

Epilepsy presenting early in childhood may be associated with a neurologically devastating clinical course and have significant implications for the child's development. There are limited published data regarding the clinicopathological features of patients who have undergone epilepsy surgery in the first year of life and the role such surgery may have in reducing seizure frequency. This study retrospectively reviews the clinicopathologic features of eight patients from a tertiary care setting who underwent surgery for epilepsy in the first year of life. Eight infants, including seven males and one female, underwent surgery for epilepsy at 3-11 months of age (median 7.5 months). Age at the time of seizure onset ranged from birth to 2 months. Epileptogenic foci were localized by electroencephalographic and radiographic studies to the right side in five patients and left side in three patients. Histopathological findings in excised tissues included cortical dysplasia (n = 7), hemimegalencephaly (n = 3), and Sturge-Weber syndrome (n = 1). Dysplasia was marked by abnormalities in cortical lamination and neuronal orientation (n = 7), neuronal cytomegaly (n = 6), increased molecular layer neurons (n = 5) and balloon cells (n = 2). One patient was known to have epidermal nevus syndrome. Two patients required additional surgery for continued seizures. At last known follow up, all but one patient, who died in the postoperative period, were alive with no or decreased seizures at postoperative intervals of 3-60 months (median 13 months). Surgery can potentially ameliorate epilepsy in patients less than 1 year of age. Most of the patients in this series had cortical dysplasia as the underlying pathology of their epilepsy.     

Aging accelerates the progression and manifestation of seizures in post-traumatic model of epilepsy

Traumatic brain injury is a major risk of post-traumatic epilepsy in a large number of individuals of different age groups. Lots of research has been done to elucidate the mechanism of post-traumatic epileptogenesis but age-related vulnerability to develop traumatic seizures is still unknown. Therefore, in the present study investigations were carried out to characterize the electrobehavioral seizure manifestation and associated alterations in young and old epileptic groups. FeCl₃ injection model was used to induce post-traumatic seizures as this model closely resembles human post-traumatic epilepsy. Synchronized video-EEG monitoring was performed to diagnose manifestation of seizures in young (4 months) and old (18 months) rats. Biochemical and ultrastructural studies were performed to determine the mechanism behind the altered age-related vulnerability for post-traumatic seizures. Our result shows that old rats were more vulnerable to post-traumatic epilepsy due to faster seizure spread and lower latency for generalization of electro-clinical seizure activity. The observed biochemical and microscopic alterations associated with old age positively correlate with the altered susceptibility to develop seizures in old epileptic groups.     

Early-life epileptiform discharges exert both rapid and long-lasting effects on AMPAR subunit composition and distribution in developing neurons

The perinatal period of brain is characterized by dynamic changes in structure and high propensity for epilepsy. Animal models have shown that alterations of AMPA receptor (AMPAR) assembly or function may be related to seizure-induced cell damage, long-lasting impairments in brain development and seizure threshold. However, effects of earlier epileptiform discharges on AMPAR composition and sub-cellular distribution remain understudied. In this study, we analyzed age-dependent variation of relative GluR1 and GluR2 protein levels in primary cultured rat cortical neurons at 7 DIV, 12 DIV, 17 DIV and 21 DIV. By inducing a single event of epileptiform activity at 6 DIV, we tested the effects of early-life seizure-like insults on AMPAR subunit distribution. We found a significant increase in synaptosomal membrane GluR1 expression in magnesium-free (MGF) medium-treated neurons at each time point detected (p < 0.05), while GluR2 expression increased at 7 DIV, and declined at 17 DIV and 21 DIV respectively (p < 0.05). That is, a trend of high GluR1 with much lower GluR2 expression on the surface membrane of epileptiform discharges experienced neurons over time in culture was presented. These findings in an in vitro model of early-life seizure may inform rodent models of epilepsy, as well as the cellular mechanism involved in epilepsy-associated brain dysfunction.     

Acute changes in the neuronal expression of GABA and glutamate decarboxylase isoforms in the rat piriform cortex following status epilepticus

The piriform cortex (PC) is the largest region of the mammalian olfactory cortex with strong connections to other limbic structures, including the amygdala, hippocampus, and entorhinal cortex. In addition to its functional importance in the classification of olfactory stimuli, the PC has been implicated in the study of memory processing, spread of excitatory information, and the facilitation and propagation of seizures within the limbic system. Previous data from the kindling model of epilepsy indicated that alterations in GABAergic inhibition in the transition zone between the anterior and posterior PC, termed here central PC, are particularly involved in the processes underlying seizure propagation. In the present study we studied alterations in GABAergic neurons in different parts of the PC following seizures induced by kainate or pilocarpine in rats. GABA neurons were labeled either immunohistochemically for GABA or its synthesizing enzyme glutamate decarboxylase (GAD) or by in situ hybridization using antisense probes for GAD65 and GAD67 mRNAs. For comparison with the PC, labeled neurons were examined in the basolateral amygdala, substantia nigra pars reticulata, and the hippocampal formation. In the PC of controls, immunohistochemical labeling for GABA and GAD yielded consistently higher neuronal densities in most cell layers than labeling for GAD65 or GAD67 mRNAs, indicating a low basal activity of these neurons. Eight hours following kainate- or pilocarpine-induced seizures, severe neuronal damage was observed in the PC. Counting of GABA neurons in the PC demonstrated significant decreases in densities of neurons labeled for GABA or GAD proteins. However, a significantly increased density of neurons labeled for GAD65 and GAD67 mRNAs was determined in layer II of the central PC, indicating that a subpopulation of remaining neurons up-regulated the mRNAs for the GAD isoenzymes. One likely explanation for this finding is that remaining GABA neurons in layer II of the central PC maintain high levels of activity to control the increased excitability of the region. In line with previous studies, an up-regulation of GAD67 mRNA, but not GAD65 mRNA, was observed in dentate granule cells following seizures, whereas no indication of such up-regulation was determined for the other brain regions examined. The data substantiate the particular susceptibility of the central PC to seizure-induced plasticity and indicate that this brain region provides an interesting tool to study the regulation of GAD isoenzymes.     

癫痫发作的神经电生理特征

癫痫是以反复发作的阵发性神经性或行为表现为特征的脑功能失调,其原因是大群神经元的不正常同步性过度放电。癫痫的发病率占总人群的0.5%-2%[1],癫痫不是单一疾病,原因不一,反映了后天与遗传的多因素病症。多数癫痫综合症可以划分为两种基本类别[2]:部分性(partial)和全身性(generalized)。部分性发作发生在大脑的局部区域内,所以又称为局灶性癫痫,而全身性发作则出现在整个前脑(至少在EEG水平)[2]。有关癫痫发作的可能机制已被广泛研究,从神经元、突触、神经元组成的网络,到解剖、生理、生化、遗传和分子生物学,都积累了大量的文献[2],…     

Temporal lobe epilepsy is a disease of faulty neuronal resonators rather than oscillators, and all seizures are provoked, usually by stress

Temporal lobe epilepsy (TLE) is the most common cause of intractable adult epilepsy. It is proposed that different kinds of epilepsy be classified into one of two categories, which correspond to the two basic kinds of neurons in the brain, that is, as diseases of oscillators or as diseases of resonators. Oscillator (or pacemacker) neurons are endowed with intrinsic conductances that permit periodic spontaneous generation of action potentials; in contrast, resonators are neurons which process information coming from sensory stimuli or from other neurons. A literature review supports the idea that TLE is a disease of faulty resonators. This means that seizures do not arise de novo in the seizure focus. The seizure focus responds to normal input with an abnormally large discharge that causes seizures. The most frequent trigger for TLE is psychological stress. A previously published theory of stress is reviewed. The stress circuit runs from the hippocampus to the amygdala to the dorsal raphe nucleus to the entorhinal cortex and back to the hippocampus. Cell loss in the dentate is central to the pathophysiology of both chronic stress and TLE, which establish a "vicious circle" relationship with one another. Once it is grasped that TLE is a disease of resonators and that all seizures in TLE are triggered, then it makes sense to address the major recognized trigger, which is stress. New therapeutic ideas for decreasing seizure frequency in TLE include the use of anti-depressants, ethosuximide (which blocks firing in the dorsal raphe nucleus), and mood-stabilizers (which block firing in the entorhinal cortex). The latter category includes several recognized anti-epileptic drugs. Drugs from all three categories should be used simultaneously and on an empirical basis in each patient.     

Hippocampal neurons and glia in epileptic EL mice

Reactive changes in hippocampal astrocytes are frequently encountered in association with temporal lobe epilepsy in humans and with drug or kindling-induced seizures in animal models. These reactive changes generally involve increases in astrocyte size and number and often occur together with neuronal loss and synaptic rearrangements. In addition to producing astrocytic changes, seizure activity can also produce reactive changes in microglia, the resident macrophages of brain. In this study, we examined the effects of recurrent seizure activity on hippocampal neurons and glia in the epileptic EL mouse, a natural model of human multifactorial idiopathic epilepsy and complex partial seizures. Timm staining was used to evaluate infrapyramidal mossy fiber organization and the optical dissector method was used to count Nissl-stained neurons in hippocampus of adult (about one year of age) EL mice and nonepileptic C57BL/6J (B6) and DDY mice. Immunostaining forglial fibrillary acidic protein (GFAP) and Iba1, an actin cross-linking molecule restricted to macrophages and microglia, was used to evaluate astrocytes and microglia, respectively. The EL mice experienced about 25–30 complex partial seizures with secondary generalization during routine weekly cage changing. No significant differences were found among the mouse strains for Timm staining scores or for neuronal counts in the CA1 and CA3 pyramidal fields or in the hilus. However, the number of GFAP-positive astrocytes was significantly elevated in the stratum radiatum and hilus of EL mice, while microglia appeared hyper-ramified and were more intensely stained in EL mice than in the B6 or DDY mice in the hilus, parietal cortex, and pyriform cortex. The results indicate that recurrent seizure activity in EL mice is associated with abnormalities in hippocampal astrocytes and brain microglia, but is not associated with obvious neuronal loss or mossy fiber synaptic rearrangements. The EL mouse can be a useful model for evaluating neuron-glia interactions related to idiopathic epilepsy.