Disturbed benzodiazepine receptor function at the onset of temporal lobe epilepsy--lomanzenil-binding in de-novo TLE

Purpose Epileptogenic foci exhibit disturbed function at the level of the benzodiazepine receptor. The aim of our study was to investigate the incidence of focal reductions of temporal benzodiazepine receptor binding (BRB) as assessed by scintigraphy with ¹²³I-iomazenil in patients with de-novo temporal lobe epilepsy (TLE). Methods Forty adult patients (age: 34 ± 12 years) with cryptogenic de-novo TLE underwent scintigraphy with ¹²³I-iomazenil. In all patients, symptomatic epilepsy was excluded by clinical investigation and MRI. The median duration of TLE was seven months, and the patients had a median of three documented seizures in their history of disease. BRB was quantified in four temporal regions covering the whole temporal lobe. Temporal asymmetry values (ASY) were compared with data determined in 13 age-matched controls yielding Z-scores for global and regional temporal BRB. Results A significant reduction of temporal BRB was found in 19 of the 40 patients (48 %), mainly in mesial temporal regions; temporal BRB asymmetries were also found in patients with a short history of seizures and low seizure frequency (≤1 year; n = 32, 13/32 (41 %)). Only in the entire cohort did the magnitude of temporal reduction of BRB correlate with the duration of TLE as well as with the number of previous partial seizures (r = 0.40 and r = 0.36; p < 0.03, respectively). Conclusions Foci of decreased BRB can already be detected at the onset of TLE; their magnitude is related to ongoing epileptic activity. Received: 20 October 2000 / Received in revised form: 29 December 2000 / Accepted: 27 January 2001     

Characterization of neuronal migration disorders in neocortical structures: extracellular in vitro recordings

The majority of patients showing neuronal migration disorders in cortical structures suffer from pharmaco-resistant epilepsy. In order to study the molecular and cellular mechanisms underlying this pronounced hyperexcitability, we used an animal model of focal cortical dysplasia demonstrating structural malformations which resemble the human pathology of microgyria. Neocortical slices prepared from adult rats, which at the day of birth received a cortical freeze lesion, were analysed in vitro with an array of eight extracellular recording electrodes to investigate the pattern and pharmacology of propagating epileptiform activity in microgyric cortex. In cortical slices exhibiting neuronal migration disorders, orthodromic synaptic stimulation elicited late recurrent activity and early epileptiform responses that spread with 0.06 m/s over ≥ 3.5 mm across the cortex. Application of a N-methyl-d -aspartate (NMDA) antagonist blocked the late recurrent activity, but not the propagation of the early epileptiform responses. The latter were blocked by an (±)-α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) antagonist, indicating that the spread of this activity was predominantly mediated by activation of AMPA receptors. A very similar response pattern could be observed in neocortical slices obtained from untreated age-matched control rats, when the slice was partially disinhibited by bath-application of 5 μm bicuculline methiodide. Stimulus-evoked epileptiform signals recorded in disinhibited slices propagated with 0.08 m/s across the cortex and showed the same sensitivity to ionotropic glutamate antagonists as in dysplastic cortex. Our results indicate that widespread structural and/or functional modifications of the AMPA receptor and possibly also of the γ-amino-butyric acid type A receptor contribute to the pronounced hyperexcitability in dysplastic cortex.     

迷走神经刺激对红藻氨酸致癫癎大鼠海马及齿状回NMDAR1的影响

目的:利用红藻氨酸(kainate,KA)致大鼠复杂部分性发作模型,观察海马及齿状回等易损脑区N-甲基-D-门冬氨酸受体1亚单位(NMDAR_1)的变化,以期进一步探明迷走神经刺激治疗癫(疒间)的作用机制。方法:免疫细胞化学法。结果:正常大鼠NMDAR_1阳性结构可见于海马各区及齿状回;KA给药后1h海马CA1、CA3、齿状回NMDAR_1的密度开始增高;3h达高峰,以后逐渐下降,24h后基本恢复正常;预先给予左侧迷走神经电刺激治疗的大鼠相应脑区NMDAR_1密度较KA致(疒间)组明显降低,具有统计学差异。结论:迷走神经刺激抑制癫(疒间)发作可能是通过降低易损脑区神经元NMDAR_1活性而发挥作用的。     

海马神经元激活物致疒间大鼠大脑皮质和海马γ-氨基丁酸受体的表达

目的 观察大鼠海马神经元在激活物作用下γ-氨基丁酸（GABA。）受体的表达,进一步探讨癫痫发病机制。方法 将大鼠海马神经尢被戊四氮（PTZ）作用后的激活物（实验组）及无血清培养基（对照组）注入大鼠侧脑室后观察其行为、脑电图（EEG）及脑组织GABA,受体表达的变化。结果 实验组大鼠注射后15～30min出现Ⅱ～Ⅲ级惊厥反应,EEG呈短程中高幅尖波、尖慢复合波;对照组的行为及EEG未见异常;各时点实验组大鼠脑组织GABA、免疫反应阳性细胞表达明显低于对照组（均P〈0．05）,对照组GABA,免疫反应阳性细胞广泛分布于大脑皮质、海马回、齿状回。结论 海马神经元激活物具有明显致痫作用,其致痫效应与GABAA受体含量下降有关。     

Dopaminergic modulation of low-Mg(2+) -induced epileptiform activity in the intact hippocampus of the newborn mouse in vitro

To investigate whether epileptiform activity in the immature brain is modulated by dopamine, we examined the effects of dopaminergic agonists and antagonists in an intact in vitro preparation of the isolated corticohippocampal formation of immature (postnatal days 3 and 4) C57/Bl6 mice using field potential recordings from CA3. Epileptiform discharges were induced by a reduction of the extracellular Mg²⁺ concentration to 0.2 mM. These experiments revealed that low concentrations of dopamine (<0.3 μM) attenuated epileptiform activity, whereas >3 μM dopamine enhanced epileptiform activity. The D1‐agonist SKF38393 (10 μM) had a strong proconvulsive effect, and the D2‐like agonist quinpirole (10 μM) mediated a weak anticonvulsive effect. The proconvulsive effect of 10 μM dopamine was completely abolished by the D1‐like receptor antagonist SCH39166 (2 μM) or the D2‐like antagonist sulpiride (10 μM), whereas the D2 antagonist L‐741626 (50 nM) and the D3 antagonist SB‐277011‐A (0.1 μM) were without effect. The anticonvulsive effect of 0.1 μM dopamine could be suppressed by D1‐like, D2, or D3 receptor antagonists. A proconvulsive effect of 10 μM dopamine was also observed when AMPA, NMDA, or GABA_A receptors were blocked. In summary, these results suggest that 1) dopamine influences epileptiform activity already at early developmental stages; 2) dopamine can bidirectionally influence the excitability; 3) D1‐like receptors mediate the proconvulsive effect of high dopamine concentrations, although the pharmacology of the anticonvulsive effect is less clear; and 4) dopamine‐induced alterations in GABAergic and glutamatergic systems may contribute to this effect. © 2012 Wiley Periodicals, Inc.     

Orexin受体拮抗剂对睡眠剥夺的戊四氮致疒间大鼠癫疒间发作及脑组织病理学变化的影响

目的探讨orexin-1受体(OX1R)和orexin-2受体(OX2R)拮抗剂对睡眠剥夺(SD)的戊四氮(PTZ)致疒间大鼠癫疒间发作及脑组织病理学变化的影响。方法雄性Wistar大鼠48只,随机分为正常对照(NC)组、PTZ组、SD+PTZ(SD)组、SD+PTZ+二甲基亚砜(DMSO)组、SD+PTZ+OX1R拮抗剂SB334867(SB)组和SD+PTZ+OX2R拮抗剂TCS OX229(TCS)组。采用改良多平台SD法,SD前及SD 48 h分别给予相应组大鼠侧脑室注射DMSO、SB或TCS。SD 72 h给予各组腹腔注射PTZ 50 mg/kg诱导癫疒间发作;观察各组大鼠癫疒间发作的潜伏期、发作等级评分、发作持续时间及死亡率;应用常规染色法观察海马的病理学变化,免疫荧光法(BrdU标记)观察神经细胞增殖的变化。结果 (1)与PTZ组比较,SD组及DMSO组疒间性发作的潜伏期明显缩短,发作等级评分、持续时间及死亡率明显增加(均P<0.001),海马CA3区神经元损害加重,海马齿状回门区和颗粒细胞下层BrdU阳性细胞数显著增多(P<0.001);SD组与DMSO组间差异无统计学意义。(2)与SD组比较...     

Neurotransmitter, receptor and biochemical changes in monkey cortical epileptic foci

Epileptic and normal Macaca mulatta monkey cortex was investigated using ligand binding techniques. Subpial injections of aluminum hydroxide gel into the left sensorimotor cortex produced stable seizure frequencies over a two year period and resulted in specific biochemical and receptor abnormalities. Pair matched CSF samples comparing epileptic and non-epileptic hemispheres showed a significant decreased GABA concentration over the epileptic side. The epileptic cortex demonstrated markedly reduced GABA receptor binding and diminished tissue GABA concentration and GAD activity. Two patterns of receptor loss were observed: nonspecific local cellular drop out involving multiple neurotransmitter receptors; and distal receptor loss which was specific for the neurotransmitter intervention pattern of the cortex. GABAergic receptor loss was more marked than receptor losses for the other neurotransmitter and was more widespread. Scatchard plot analysis demonstrated that the diminished GABAergic receptors within the focus were due to receptor loss and not affinity changes. Spearman rank correlations showed a significant correlation only between the degree of GABAergic receptor loss or decrease in GAD activity and the seizure frequency. Epilepsy appears to be a multifactoral disorder with multiple neuroreceptor abnormalities, the most notable of which are the destruction of GABAergic neurons and GABA receptors.     

Screening of GABRB3 in French‐Canadian families with idiopathic generalized epilepsy

Mutations in the GABRB3 have been recently associated with childhood absence epilepsy (CAE) in families from Honduras and Mexico. In this study, we aimed to determine the frequency of mutation in this gene in our cohort of families with CAE and other related idiopathic generalized epilepsy (IGE) syndromes. We screened the open reading frame of GABRB3 in 183 French‐Canadian individuals with IGE, including 88 with CAE. A total of nine single nucleotide polymorphisms (SNPs) have been identified, five of which are novel. The previously described P11S missense mutation was found in three affected and one unaffected individuals from a French‐Canadian family. However, the P11S variant was also found in one of our 190 control individuals of French‐Canadian origin, suggesting that this variant is rather a rare polymorphism in this population. Further screening of other IGE cohorts from various ethnic origins would help to confirm the association between this rare functional variant and epilepsy.     

A case of anti‐NMDA receptor encephalitis revealed by insular epilepsy

Anti‐N‐methyl‐D‐aspartate receptor (NMDAR) encephalitis is an autoimmune disorder of the central nervous system that typically manifests predominantly as a psychiatric disorder. However, other manifestations such as epileptic seizures, abnormal movements, and memory or language complications are not unusual. Here, we report the case of a young man who presented with a new‐onset epilepsy, with ictal semiology suggestive of insular involvement; this hypothesis was supported by a PET‐CT study. Anti‐NMDAR antibodies were found in the CSF, confirming the diagnosis of anti‐NMDAR encephalitis. A review of the literature reveals that epilepsy can be the first manifestation of NMDAR encephalitis, with a clear male predominance. Despite its rarity, neurologists should consider this diagnosis for any young patient developing a new‐onset epilepsy with temporal or insular features, particularly if the patient is male. Other cognitive or behavioural signs, even very subtle, should also prompt diagnosis.     

难治性颞叶癫痫脑组织IL-6、IL-6受体及sIL-6R、 sgp130的表达及意义

目的 探讨IL-6、IL-6膜受体(IL-6R)及其下游信号转导相关分子在颞叶癫痫(TLE)发生中的作用. 方法 选择自2010年1月至2010年12月在第三军医大学新桥医院神经外科行手术治疗的TLE患者40例(TLE组),同期行手术治疗的外伤、高血压脑出血等患者40例(对照组);收集其手术过程中切除的颞叶组织.利用RT-PCR、ELISA等方法分析IL-6、IL-6R、sIL-6R以及sgp130的mRNA或蛋白水平的表达变化情况. 结果 TLE组和对照组中均可检测到IL-6和IL-6R mRNA的表达,但TLE组致病灶中IL-6和IL-6R mRNA水平均显著高于对照组,差异有统计学意义(P＜0.05).ELISA结果提示,sIL-6R在TLE组致痫灶中的表达量与对照组比较明显增高,差异有统计学意义(P＜0.05);sgpl30的含量略高于对照组,差异没有统计学意义(P＞0.05). 结论 局部高浓度的IL-6通过经典信号转导或者跨信号转导机制作用于TLE病灶细胞,影响这些细胞的生物学功能,参与癫痫发生过程.     

内源性安定样活性在癫痫患者脑脊液释放情况的初步研究

已证实哺乳类动物脑中存在有安定受体的内源性配基。本文应用放射受体法检测了１５例癫痫（ＥＰ）患者和１０例正常对照者脑脊液中安定样受体结合活性，结果显示ＥＰ患者脑脊液内源性安定样活性（２２．７０±８．３４％Ｉｎｈｉｂｉｔｏｎ）明显低于对照组（３９．０４±１４．３５％Ｉｎｈｉｂｉｔｉｏｎ），Ｐ＜０．０１。ＥＰ发作类型、ＥＰ发作控制与否等同内源性安定样活性改变之间未发现有明显关系。内源性安定的真正来源尚不清楚，但本文结果提示ＥＰ患者中枢神经系统内源性安定样活性的下降，通过对γ—氨基丁酸能神经传递的负性作用，而可能为ＥＰ发作的原因之一     

Opioid receptor alterations in a genetic model of generalized epilepsy

Autoradiography was used to examine opioid receptor binding in the Mongolian gerbil, a genetic model of the epilepsies. Coronal brain sections of seizure-resistant (SR) and seizure-sensitive (SS) (both pre- and post-seizure conditions) gerbils were labeled with [3H]dihydromorphine. SS (pre-seizure) gerbils demonstrated overall greater brain opioid binding when compared to SR animals. The periaqueductal gray, substantia nigra and medial geniculate body were specific areas in SS (pre-seizure) gerbils which demonstrated highly significant increases in opioid binding compared to SR animals (% increase vs SR were 98%, 91.3% and 42.9%, respectively). Scatchard analysis demonstrated that the increase in opioid binding was due to an increase in the total number of receptors without a significant change in receptor affinity (i.e. periaqueductal gray area: total number of binding sites was 12.7 (SR) and 18.0 fmol/mg tissue (SS pre-seizure), while Kd values were 4.0 (SR) and 4.0 mM (SS pre-seizure). Opioid binding was also increased in the SS (post-seizure) animals when compared to SR animals, especially in the substantia nigra. However, when compared to SS (pre-seizure) gerbils, there was a general but not significant, decrease in opioid binding in SS post-seizure gerbils. The increased opioid binding in the SS (pre-seizure) gerbil compared to SR gerbils could reflect an up-regulation due to a deficit in endogenous ligand (e.g. a deficit in synthesis or decreased release) which could underlie the seizure diathesis in the gerbil.     

海人酸致大鼠海马结构GABA_B受体亚单位表达的研究

目的:探讨海人酸诱导大鼠颞叶癫(EP)发作后2种γ-氨基丁酸(GABA)受体亚单位GABABR亚单位1a(GBR1a)和GABABR亚单位2(GBR2)在EP发生、发展中的作用。方法:运用原位杂交及免疫组化法,检测EP发作后GABABR亚单位mRNA及蛋白在海马的表达。结果:致早期CA1和CA3区2种亚单位mRNA表达持续低下后逐渐增加,DG区则暂时性下降后很快回升;而免疫反应早期却未见明显改变,随后CA1和CA3区表达处于低水平,DG区和颞叶皮质表达下降后很快恢复。结论:致后2种GABAB受体亚单位基因和蛋白表达上调为颞叶EP的内源性自我保护机制。     

美解眠急、慢性致癫痫大鼠海马和大脑皮质糖皮质激素受体变化的研究

目的　观察癫痫大鼠大脑皮质、海马糖皮质激素受体 (GR)的改变 ,阐明 GR在癫痫发生发展中的作用。方法　采用美解眠皮下注射方式建立大鼠癫痫模型。应用免疫组织化学 ABC法测定 60只 SD雄性大鼠大脑皮质及海马齿状回 GR阳性细胞数目的变化。结果　急性致癫痫组大鼠大脑皮质、海马齿状回 GR阳性细胞数显著低于对照组 (P <0 .0 0 1 ) ;慢性致癫痫组大鼠大脑皮质、海马齿状回 GR阳性细胞数显著高于对照组 (P <0 .0 1 )和急性致癫痫组 (P<0 .0 0 1 )。结论　大脑皮质和海马 GR水平的变化可能与癫痫发病有关。     

实验性癫癎大鼠发作后海马γ-氨基丁酸B受体亚单位的表达及其激动剂的影响

目的观察海人酸(KA)诱导的实验性癫癎(EP)大鼠发作后海马γ-氨基丁酸B受体(GABABR)亚单位mRNA表达及其激动剂巴氯芬的影响。方法运用原位杂交法检测各实验组大鼠EP发作后及巴氯芬干预后海马区GABABR亚单位GAR1a及GAR2 mRNA表达。结果KA致癎早期(6~12h)2种亚单位mRNA表达水平广泛下降,至1d仍明显低于对照组(均P<0.05),但齿状回(DG)区mRNA表达开始回升,3d后表达水平已明显高于对照组(P<0.05),而CA1与CA3区表达仍维持低水平(均P<0.05),但其表达水平渐向对照组水平恢复。巴氯芬干预后亚单位表达明显下降的时间点延迟,且表达水平明显高于非干预的致癎组(P<0.05~0.01)。结论致癎鼠2种亚单位表达下降后又上调为颞叶EP的内源性自我保护机制;巴氯芬促进2种亚单位表达,增强GABA抑制作用,有利于控制EP,为筛选针对GABABR亚单位的抗癎药提供新途径。     

Orexin-1受体拮抗剂对慢性点燃癫大鼠学习记忆的影响及海马神经细胞的增殖变化

目的:研究orexin-1受体(OX1R)拮抗剂(SB334867,SB)对戊四氮(PTZ)慢性点燃癫大鼠空间学习记忆能力及海马齿状回神经细胞增殖的影响。方法:Wistar大鼠随机分为①对照组[腹腔和侧脑室均注射生理盐水(NS)];②PTZ组(腹腔注射PTZ+侧脑室注射NS);③PTZ+orexin-A(OXA)组(腹腔注射PTZ+侧脑室注射OXA);④PTZ+SB组(腹腔注射PTZ+侧脑室注射SB);⑤PTZ+SB+OXA组(腹腔注射PTZ+侧脑室注射SB和OXA)。观察各组大鼠的空间学习记忆能力及海马齿状回区BrdU+和BrdU+/NeuN+细胞的表达。结果:与PTZ+OXA组比较,PTZ+SB+OXA组大鼠逃避潜伏期延长、穿越平台象限的次数减少(P<0.05)。免疫荧光显示,PTZ+OXA组大鼠齿状回区BrdU+和BrdU+/NeuN+细胞表达增多(P<0.01),而PTZ+SB+OXA组大鼠齿状回区BrdU+/NeuN+细胞表达比PTZ+OXA组减少(P<0.01)。结论:OXA通过OX1R能改善癫大鼠的空间学习记忆能力,可能与OX1R介导的海马齿状回神经细胞增殖与分化作用有关。     

Neurosteroid Withdrawal Model of Perimenstrual Catamenial Epilepsy

PURPOSE: Perimenstrual catamenial epilepsy, the increase in seizure frequency that some women with epilepsy experience near the time of menstruation, may in part be related to withdrawal of the progesterone metabolite allopregnanolone, an endogenous anticonvulsant neurosteroid that is a potent positive allosteric gamma-aminobutyric acidA (GABA(A)) receptor modulator. The objective of this study was to develop an animal model of perimenstrual catamenial epilepsy for use in evaluating drug-treatment strategies. METHODS: A state of prolonged high serum progesterone (pseudopregnancy) was induced in 26-day-old female rats by sequential injection of pregnant mares' serum gonadotropin and human chorionic gonadotropin. Neurosteroid withdrawal was induced by treatment with finasteride (100 mg/kg, i.p.), a 5alpha-reductase inhibitor that blocks the conversion of progesterone to allopregnanolone. Plasma progesterone and allopregnanolone levels were measured by gas chromatography/electron capture negative chemical ionization mass spectrometry. Seizure susceptibility was evaluated with the convulsant pentylenetetrazol (PTZ). RESULTS: Plasma allopregnanolone levels were markedly increased during pseudopregnancy (peak level, 55.1 vs. control diestrous level, 9.3 ng/mL) and were reduced by 86% 24 h after finasteride treatment (6.4 ng/mL). Progesterone levels were unaffected by finasteride. After finasteride-induced withdrawal, rats showed increased susceptibility to PTZ seizures. There was a significant increase in the number of animals exhibiting clonic seizures when challenged with subcutaneous PTZ (60 mg/kg) compared with control pseudopregnant animals not undergoing withdrawal and nonpseudopregnant diestrous females. The CD50 (50% convulsant dose) was 46 mg/kg, compared with 73 mg/kg in nonwithdrawn pseudopregnant animals and 60 mg/kg in diestrous controls. The threshold doses for induction of various seizure signs, measured by constant intravenous infusion of PTZ, were reduced by 30-35% in neurosteroid-withdrawing animals compared with control diestrous females. No change in threshold was observed in pseudopregnant rats treated from days 7 to 11 with finasteride, demonstrating that high levels of progesterone alone do not alter seizure reactivity. CONCLUSIONS: Neurosteroid withdrawal in pseudopregnant rats results in enhanced seizure susceptibility, providing an animal model of perimenstrual catamenial epilepsy that can be used for the evaluation of new therapeutic approaches.     

A child with hyperekplexia and epileptic myoclonus

Hyperekplexia is a rare neurogenetic disorder characterized by startle. Accurate diagnosis of this notorious mimicker of epilepsy is important to prevent life‐threatening apnoea. We report a novel case of concomitant GLRA1‐related hyperkeplexia and myoclonic epilepsy. A toddler with daily paroxysms of head drops and falls presented with epileptic myoclonus on EEG, however, whole‐exome sequencing revealed hyperekplexia‐related GLRA1 mutation. The boy eventually developed spells induced by noise and surprise. All his spells remitted upon treatment with clonazepam. Paediatricians and paediatric neurologists should be aware of this possible mixed presentation in order to appropriately tailor medication regimens and treatment goals. [Published with video sequence on www.epilepticdisorders.com ].     

Mossy Fiber Zinc and Temporal Lobe Epilepsy: Pathological Association with Altered "Epileptic"γ-Aminobutyric Acid A Receptors in Dentate Granule Cells

Summary: Temporal lobe epilepsy is associated with circuit rearrangements within the hippocampus. Mossy fibers sprout and pathologically innervate the inner molecular layer of the dentate gyrus, providing a recurrent excitatory pathway not present in the control brain. In addition to releasing glutamate, these recurrent collaterals also release zinc, which can accumulate in high concentrations in the extracellular space. Accompanying these dentate gyrus circuit rearrangements are alterations in the subunit expression patterns and pharmacology of γ-aminobutyric acid A (GABA_A) receptors in dentate granule cells. In normal, control granule cells, GABA_A receptors are zinc insensitive as a result of high levels of expression of the α1 subunit in these cells. In epileptic brain, expression of α1 subunits decreases and expression of α4 and δ subunits increases, leading to the assembly of GABA_A receptors that are exquisitely zinc sensitive. This temporal and spatial association of the expression of zinc-sensitive GABA_A receptors and the emergence of a zinc-delivery system unique to the epileptic hippocampus has led to the formulation of an hypothesis that suggests that zinc release during repetitive activation of the dentate gyrus may lead to a catastrophic failure of inhibition under conditions mediating seizure initiation. This could contribute to the limbic hyperexcitability characteristic of temporal lobe epilepsy.