Pathogenesis Of Temporal Lobe Epilepsy Research Articles

Myocyte-specific enhancer binding factor 2A expression is downregulated during temporal lobe epilepsy

Myocyte-specific enhancer binding factor 2A (MEF2A) is a multifunctional nuclear protein that regulates synaptogenesis, dendritic morphogenesis, and neuronal survival. This study aimed to investigate the expression pattern of MEF2A in epileptogenic processes. MEF2A expression was detected in 20 temporal neocortex tissue samples from patients with temporal lobe epilepsy (TLE) and 20 samples from trauma patients without epilepsy by real-time quantitative polymerase chain reaction, immunohistochemistry, double-label immunofluorescent staining, and western blot analysis. In addition, the expression patterns of MEF2A in the hippocampus and adjacent cortex of a lithium–pilocarpine-induced TLE rat model and control rats were examined. MEF2A was found to be expressed in the nuclei of neurons but not in the dendrites of neurons and astrocytes. MEF2A expression was significantly downregulated in temporal neocortex of humans and rats with TLE compared to the control groups. In addition, in the lithium–pilocarpine-induced TLE model, MEF2A expression dynamically decreased within 2 months. Taken together, these data suggest that MEF2A is involved in the pathogenesis of TLE.

Machine learning classification of mesial temporal sclerosis in epilepsy patients

Background and purposeNovel approaches applying machine-learning methods to neuroimaging data seek to develop individualized measures that will aid in the diagnosis and treatment of brain-based disorders such as temporal lobe epilepsy (TLE). Using a large cohort of epilepsy patients with and without mesial temporal sclerosis (MTS), we sought to automatically classify MTS using measures of cortical morphology, and to further relate classification probabilities to measures of disease burden. Materials and methodsOur sample consisted of high-resolution T1 structural scans of 169 adults with epilepsy collected across five different 1.5T and four different 3T scanners at UCLA. We applied a multiple support vector machine recursive feature elimination algorithm to morphological measures generated from FreeSurfer's automated segmentation and parcellation in order to classify Epilepsy patients with MTS (n=85) from those without MTS (N=84). ResultsIn addition to hippocampal volume, we found that alterations in cortical thickness, surface area, volume and curvature in inferior frontal and anterior and inferior temporal regions contributed to a classification accuracy of up to 81% (p=1.3×10−17) in identifying MTS. We also found that MTS classification probabilities were associated with a longer duration of disease for epilepsy patients both with and without MTS. ConclusionsIn addition to implicating extra-hippocampal involvement of MTS, these findings shed further light on the pathogenesis of TLE and may ultimately assist in the development of automated tools that incorporate multiple neuroimaging measures to assist clinicians in detecting more subtle cases of TLE and MTS.

Reactive oxygen species mediate cognitive deficits in experimental temporal lobe epilepsy

Cognitive dysfunction is an important comorbidity of temporal lobe epilepsy (TLE). However, no targeted therapies are available and the mechanisms underlying cognitive impairment, specifically deficits in learning and memory associated with TLE remain unknown. Oxidative stress is known to occur in the pathogenesis of TLE but its functional role remains to be determined. Here, we demonstrate that oxidative stress and resultant processes contribute to cognitive decline associated with epileptogenesis. Using a synthetic catalytic antioxidant, we show that pharmacological removal of reactive oxygen species (ROS) prevents 1) oxidative stress, 2) deficits in mitochondrial oxygen consumption rates, 3) hippocampal neuronal loss and 4) cognitive dysfunction without altering the intensity of the initial status epilepticus (SE) or epilepsy development in a rat model of SE-induced TLE. Moreover, the effects of the catalytic antioxidant on cognition persisted beyond the treatment period suggestive of disease-modification. The data implicate oxidative stress as a novel mechanism by which cognitive dysfunction can arise during epileptogenesis and suggest a potential disease-modifying therapeutic approach to target it.

Reduced Pumilio-2 expression in patients with temporal lobe epilepsy and in the lithium-pilocarpine induced epilepsy rat model.

Drosophila Pumilio (Pum), a homolog of mammalian Pum2, plays an important role in translational regulation in the central nervous system (CNS), particularly for dendrite outgrowth and neuronal excitability. We investigated the expression pattern and cellular distribution of Pum2 in patients with drug-refractory temporal lobe epilepsy (TLE) and rats with lithium chloride-pilocarpine-induced epilepsy. Real-time quantitative PCR (RT-qPCR), Western blot, immunohistochemistry, and double-labeled immunofluorescence were utilized to determine the expression level and distribution of Pum2 in temporal neocortex tissues from patients with intractable TLE (n=20) and patients with severe head trauma (n=20) in addition to the hippocampus and adjacent cortex of rats with lithium chloride-pilocarpine-induced TLE and controls. Pum2 was expressed in the cell bodies and dendrites of neurons but did not colocalize with glial fibrillary acidic protein-positive astrocytes or propidium iodide (PI) in nuclei. The expression of Pum2 was significantly reduced in patients and rats with TLE in comparison to controls (P<0.05). Pum2 expression was less in patients with TLE and a rodent model of epilepsy, suggesting that decreased expression of Pum2 may be involved in the pathogenesis of TLE.

Up-regulated cytoplasmic FMRP-interacting protein 1 in intractable temporal lobe epilepsy patients and a rat model

Cytoplasmic FMRP-interacting protein 1 (CYFIP1) is a multifunctional protein which expresses highly at excitatory synapses and can locally regulate actin cytoskeletal dynamics, spine morphology and synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor lateral diffusion. Altered synaptic actin plays a role in the pathogenesis of epilepsy. The aim of this study was to investigate the expression pattern of CYFIP1 in temporal lobe epilepsy (TLE). Protein and mRNA expression levels were compared in temporal lobe tissue from patients with TLE versus trauma patients without TLE using quantitative real-time polymerase chain reaction (qRT-PCR), double-label immunofluorescence and Western blot analysis. We have further determined the expression pattern of Cyfip1 mRNA and protein in the hippocampus and adjacent cortex of a common rat model of TLE, lithium–pilocarpine treatment, compared to control rats. CYFIP1 expression was significantly up-regulated in the temporal neocortex of patients with intractable TLE and pilocarpine-treated rats compared to control groups. CYFIP1 localizes to the cytoplasm of neurons, and is not expressed in the astrocytes. Furthermore, CYFIP1 expression levels increased significantly in the two months after pilocarpine treatment, which corresponds to the period of epileptogenesis. Thus, our results indicate that CYFIP1 may be involved in the pathogenesis of TLE.

The neurovascular unit: the contribution of endothelial cells and leukocytes

The conventional notion that neurons are exclusively responsible for brain signaling is increasingly challenged by the idea that brain function in fact depends on a complex interplay between neurons, glial cells, vascular endothelium, and immunerelated blood cells. But it’s only in the last years that we consider the cerebrovasculature not simply as a passive conduit, but rather as a highly dynamic multicellular structure capable of integrating and responding to both systemic and neural cues (1). We are focusing since the last decade to the role of non-neuronal players modulating the neuronal activity. We will report experimental evidences of the contribution of endothelial cells and leukocytes in the neuronal abnormal excitation. In particular, our recently obtained-data demonstrated the role of endothelial cells in the initiation of the pathological cascade induced by Quantum-dots nanoparticles, as well as the primary role of cerebral endothelial cells in the pathogenesis of temporal lobe epilepsy induced by pilocarpine. We will furthermore report data indicating the role of neurovascular unit different players in the pharmaco-resistant epilepsy.

FDG-PET and NeuN-GFAP immunohistochemistry of hippocampus at different phases of the pilocarpine model of temporal lobe epilepsy.

Purpose: Hippocampal glucose hypometabolism has been implicated in the pathogenesis of temporal lobe epilepsy (TLE). However, the underlying pathophysiological basis for this hypometabolism remains elusive. The aim of this study was to investigate the relationship between hippocampal hypometabolism and the histological changes seen in rats after systemic pilocarpine treatment.Methods: 18F-fluorodeoxyglucose (FDG) small-animal positron emission tomography (microPET) was performed on day zero (untreated), day seven (latent) and day sixty (chronic phase) after the initial status epilepticus. The microPET imaging data were correlated with the immunoreactivity of neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP) in the hippocampus at each time point.Results: 18F-FDG-microPET images showed the hippocampus presented with persistent hypometabolism during epileptogenesis and partly recovered in the chronic phase. Hippocampal glucose uptake defects correlate with NeuN immunoreactivity in the latent phase and GFAP immunoreactivity in the chronic phase.Conclusions: Severe glucose hypometabolism in the hippocampus during the latent phase correlates with neuronal cell loss. The partial recovery of hippocampal glucose uptake in the chronic phase may be due to astrogliosis.

Histamine H3 receptor antagonism by ABT-239 attenuates kainic acid induced excitotoxicity in mice

The multifaceted pathogenesis of temporal lobe epilepsy (TLE) offers a number of adjunctive therapeutic prospects. One such therapeutic strategy could be targeting H3 receptor (H3R) by selective H3R antagonists which are perceived to have antiepileptic and neuroprotective potential. Kainic acid (KA) induced seizure, a reliable model of TLE, triggers epileptogenic events resulting from initial neuronal death and ensuing recurring seizures. The present study aimed to determine whether pre-treatment with ABT-239, a novel H3R antagonist, and its combinations with sodium valproate (SVP) and TDZD-8 (glycogen synthase kinase-3β (GSK3β) inhibitor) can prevent the excitotoxic events in mice exposed to KA (10mg/kg i.p.). ABT-239 (1 and 3mg/kg i.p.) significantly attenuated KA-mediated behavioural and excitotoxic anomalies and restored altered expression of Bax, cleaved caspase-3, phospho-Akt (Ser473) and cAMP response element binding protein (CREB). Surprisingly, restoration of Bcl2 and phospho-GSK3β (Ser9) by ABT-239 did not reach the level of statistical significance. Co-administration of ABT-239 (1 and 3mg/kg) with a sub-effective dose of SVP (150mg/kg i.p.) yielded improved efficacy than when given alone. Similarly, low and high dose combinations of ABT-239 (1 and 3mg/kg) with TDZD-8 (5 and 10mg/kg i.p.) produced greater neuroprotection than any other treatment group. Our findings suggests a neuroprotective potential of ABT-239 and its combinations with SVP and TDZD-8 against KA-induced neurotoxicity, possibly mediated through in part each by modulating Akt/GSK3β and CREB pathways. The use of H3R antagonists as adjuvant in the treatment of human TLE might find potential utility, and can be pursued further.

Mapping the temporal pole with a specialized electrode array: technique and preliminary results

Temporopolar cortex plays a crucial role in the pathogenesis of temporal lobe epilepsy and subserves important cognitive functions. Because of its shape and position in the middle cranial fossa, complete electrode coverage of the temporal pole (TP) is difficult to achieve using existing devices. We designed a novel TP electrode array that conforms to the surface of temporopolar cortex and achieves dense electrode coverage of this important brain region. A multi-pronged electrode array was designed that can be placed over the surface of the TP using a straightforward insertion technique. Twelve patients with medically intractable epilepsy were implanted with the TP electrode array for purposes of seizure localization. Select patients underwent cognitive mapping by electrocorticographic (ECoG) recording from the TP during a naming task. Use of the array resulted in excellent TP electrode coverage in all patients. High quality ECoG data were consistently obtained for purposes of delineating seizure activity and functional mapping. During a naming task, significant increases in ECoG power were observed within localized subregions of the TP. One patient developed a transient neurological deficit thought to be related to the mass effect of multiple intracranial recording arrays, including the TP array. This deficit resolved following removal of all electrodes. The TP electrode array overcomes limitations of existing devices and enables clinicians and researchers to obtain optimal multi-site recordings from this important brain region.

In Vivo Measurement of Hippocampal GABAA/cBZR Density with [18F]-Flumazenil PET for the Study of Disease Progression in an Animal Model of Temporal Lobe Epilepsy

PurposeImbalance of inhibitory GABAergic neurotransmission has been proposed to play a role in the pathogenesis of temporal lobe epilepsy (TLE). This study aimed to investigate whether [18F]-flumazenil ([18F]-FMZ) PET could be used to non-invasively characterise GABAA/central benzodiazepine receptor (GABAA/cBZR) density and affinity in vivo in the post-kainic acid status epilepticus (SE) model of TLE.MethodsDynamic [18F]-FMZ -PET scans using a multi-injection protocol were acquired in four male wistar rats for validation of the partial saturation model (PSM). SE was induced in eight male Wistar rats (10 weeks of age) by i.p. injection of kainic acid (7.5–25 mg/kg), while control rats (n = 7) received saline injections. Five weeks post-SE, an anatomic MRI scan was acquired and the following week an [18F]-FMZ PET scan (3.6–4.6 nmol). The PET data was co-registered to the MRI and regions of interest drawn on the MRI for selected structures. A PSM was used to derive receptor density and apparent affinity from the [18F]-FMZ PET data.Key FindingsThe PSM was found to adequately model [18F]-FMZ binding in vivo. There was a significant decrease in hippocampal receptor density in the SE group (p<0.01), accompanied by an increase in apparent affinity (p<0.05) compared to controls. No change in cortical receptor binding was observed. Hippocampal volume reduction and cell loss was only seen in a subset of animals. Histological assessment of hippocampal cell loss was significantly correlated with hippocampal volume measured by MRI (p<0.05), but did not correlate with [18F]-FMZ binding.SignificanceAlterations to hippocampal GABAA/cBZR density and affinity in the post-kainic acid SE model of TLE are detectable in vivo with [18F]-FMZ PET and a PSM. These changes are independent from hippocampal cell and volume loss. [18F]-FMZ PET is useful for investigating the role that changes GABAA/cBZR density and binding affinity play in the pathogenesis of TLE.

Decreased expression of Gab2 in patients with temporal lobe epilepsy and pilocarpine-induced rat model

Growth factor receptor bound protein-2 associated binding protein-2 (Gab2) is widely expressed in the central nervous system, and participates in multiple signaling pathways. Recent studies showed that Gab2 was involved in the pathogenesis of Alzheimer's disease (AD). Gab2 reduces tau phosphorylation levels and is associated with cellular apoptosis and differentiation. However, whether Gab2 was also involved in the pathogenesis of epilepsy, remains unknown. This study aimed to investigate the expression pattern of Gab2 protein in brains with temporal lobe epilepsy (TLE) and in pilocarpine-induced rat model of TLE. Western blot, immunohistochemistry, and immunofluorescence were used to assess the location and the expression level of Gab2 in the neocortex of the temporal lobe in patients with TLE and in rat model of epilepsy. Results showed that Gab2 protein was expressed mainly in the membranes and cytoplasm of neurons in the cortex and hippocampus. Gab2 protein expression was remarkably reduced in temporal neocortex of TLE patients. In hippocampus and adjacent cortex in rat epilepsy model, Gab2 expression was decreased at different time points after kindling compared with the controls, and the lowest level of Gab2 expression occurred at 1 week. Thus, significant reductions of Gab2 protein in both TLE patients and epilepsy rats suggest that Gab2 may play an important role in the pathogenesis of TLE.

Expression of Toll-like receptor 4 in hippocampus of rat model with temporal lobe epilepsy

Objective To investigate the expression of Toll-like receptor 4 (TLR4) protein in hippocampus of rat model with temporal lobe epilepsy after status epilepticus (SE) and explore its function in the pathogenesis of temporal lobe epilepsy. Methods Rat model with temporal lobe epilepsy was induced by lithium chloride (LiCl)-pilocarpine. Total protein was extracted from hippocampus and rat brain slices were obtained at different time points (0, 1, 6, 12, 24, 48 h and 7, 10, 30, 50 d) after SE. Western blotting and immunohistochemical staining were used for detection of the expression of TLR4 in the hippocampus. Results The results of Western blotting showed the TLR4 protein expression at 0, 1, 6, 12, 24, 48 h and 7, 10, 30 d after SE was higher than that in the control group (P 0.05). Conclusion TLR4 protein was mainly expressed in cytoplasm ofpyramidal cells in CA3 area of hippocampus. TLR4 protein expression in the hippocampus was increased in varying degrees at different observation time points after SE, indicating that TLR4 may play an important role in the development of epilepsy. doi：10.3969/j.issn.1672-6731.2013.12.009

Monocarboxylate transporters in temporal lobe epilepsy: roles of lactate and ketogenic diet

Epilepsy is a serious neurological disorder that affects approximately 1 % of the general population, making it one of the most common disorders of the central nervous system. Furthermore, up to 40 % of all patients with epilepsy cannot control their seizures with current medications. More efficacious treatments for medication refractory epilepsy are therefore needed. A better understanding of the mechanisms that cause this disorder is likely to facilitate the discovery of such treatments. Impairment in cerebral energy metabolism has been proposed as a possible causative factor in the pathogenesis of temporal lobe epilepsy (TLE), which is one of the most common types of medication-refractory epilepsies in adults. In this review, we will discuss some of the current hypotheses regarding the possible causal relationship between brain energy metabolism and TLE. Emphasis will be placed on the role of energy substrates (lactate and ketone bodies) and their transporter molecules, particularly monocarboxylate transporters 1 and 2 (MCT1 and MCT2). We recently reported that the cellular distribution of MCT1 and MCT2 is perturbed in the hippocampus in patients with TLE. The changes may be an adaptive response aimed at keeping high levels of lactate in the epileptic tissue, which may serve to counteract epileptic activity by downregulating cAMP levels through the lactate receptor GPR81, newly discovered in hippocampus. We propose that the perturbation of MCTs may be further involved in the pathophysiology of TLE by influencing brain energy homeostasis, mitochondrial function, GABA-ergic and glutamatergic neurotransmission, and flux of lactate through the brain.

Altered expression of pannexin proteins in patients with temporal lobe epilepsy

The aim of the present study was to investigate the expression of the pannexin (Panx) proteins, Panx1 and Panx2, in the temporal lobe tissue of patients with temporal lobe epilepsy (TLE). Immunohistochemistry and western blotting methods were used to localize and quantify Panx1 and Panx2 in the surgically removed brain tissue of patients with TLE (n=37). The results were then compared with non-epileptogenic controls (n=9). Panx1 and Panx2 expression was detected in the temporal lobe cortex of patients with TLE and in the control tissues. Panx1 and Panx2 proteins were expressed in all layers of the epileptic cortex, but predominantly in layers II and III of the cortex in the control group. Panx1 protein expression was significantly higher in the temporal lobe cortex of the patients with TLE than in the controls (P<0.05; t-test); however, no significant differences were identified in the Panx2 expression levels between the patients and the controls (P>0.05; t-test). The expression of the two Panx proteins in the tissue layers of the epileptic cortex varied in the patients and controls. The results indicate that Panx channels may be involved in the pathogenesis of TLE.

Differences in the hippocampal frequency of creatine inclusions between the acute and latent phases of pilocarpine model defined using synchrotron radiation-based FTIR microspectroscopy

Temporal lobe epilepsy (TLE) is the most common type of epilepsy in adults. Of the animal models developed to investigate the pathogenesis of TLE, the one with pilocarpine-induced seizures is most often used. After pilocarpine administration in animals, three distinct periods—acute, latent, and chronic—can be distinguished according to their behavior. The present paper is the continuation of our previous study which has shown an increased occurrence of creatine inclusions in rat hippocampal formations from the acute phase of pilocarpine-induced status epilepticus (SE) and positive correlation between their quantity and the total time of seizure activity within the observation period. In this paper, we tried to verify if anomalies in hippocampal creatine accumulation were the temporary or permanent effect of pilocarpine-evoked seizures. To realize this purpose, male Wistar rats in the latent phase (3 days after pilocarpine administration) were examined. The results obtained for the period when stabilization of animal behavior and EEG occurs were afterwards compared with ones obtained for the acute phase of pilocarpine-induced SE and for naive controls. To investigate the frequency of creatine inclusions within the hippocampal formation as well as in its selected areas (sectors 1–3 of Ammon’s horn (CA1–CA3), dentate gyrus (DG), and hilus of DG) and cellular layers (pyramidal, molecular, multiform, and granular cell layers), synchrotron radiation-based Fourier-transform infrared microspectroscopy was used. The applied technique, being a combination of light microscopy and infrared spectroscopy, allowed us to localize microscopic details in the analyzed samples and provided information concerning their chemical composition. Moreover, the use of a synchrotron source of IR radiation allowed us to carry out the research at the diffraction-limited spatial resolution which, because of the typical size of creatine inclusions (from a few to dozens of micrometers), was necessary for our study. The comparison of epileptic animals in the latent phase with controls showed statistically significant increase in the number of creatine inclusions for most of the analyzed hippocampal regions, all examined cellular layers, as well as the whole hippocampal formation. Moreover, for the hilus of the DG and CA3 area, the number of creatine deposits was higher in the latent than in the acute phase after pilocarpine injection. In light of the obtained results, an anomaly in the hippocampal accumulation of creatine is the long-term effect of pilocarpine-evoked seizures, and the intensity of this phenomenon may increase with time passing from the primary injury. FigureThe comparison of baseline corrected IR spectra recorded in selected creatine inclusion and nervous tissue (A). The microscopic view of the DG hippocampal area from the animal representing the SE72H group; creatine deposits are visible as darker points (B). The distributions of selected creatine bands: 2,800 cm−1 (C), 1,398 cm−1 (D), and 1,304 cm−1 (E) in the rectangular tissue area visible in part (B)

Tenidap, an agonist of the inwardly rectifying K+ channel Kir2·3, delays the onset of cortical epileptiform activity in a model of chronic temporal lobe epilepsy

Objective: Inwardly rectifying K+ (Kir) channel, Kir2·3, has been found down-regulated in the hippocampus of chronic temporal lobe epileptic (cTLE) patients which may underline the mechanism of epilepsy. Tenidap is an agonist of Kir2·3. However, the effect of tenidap on cTLE remains obscure. The aim of the present study was to observe the relationship between Kir2·3 and the pathogenesis of cTLE, and to explore the potential effect of Kir agonists as anti-epileptic drugs.Methods: The pilocarpine temporal lobe epilepsy (TLE) rat model was established and status epilepticus (SE) was induced in rats. The rats were divided into four groups based on time points (0 hours, 6 hours, 72 hours, and two weeks) after SE termination. The dynamic changes in Kir2·3 mRNA and protein expression in the hippocampus were detected at each time point by reverse transcription polymerase chain reaction (RT-PCR) and western blotting to determine an appropriate time for further intervention and observation. Then, tenidap was administered and its effect on the expression of Kir2·3 mRNA/protein and the electroencephalogram (EEG) wave was documented at predetermined time points.Results: The pattern of Kir2·3 mRNA and protein expression was bimodal, as it increased immediately after SE and declined at two weeks, when compared with the control group. Down-regulation of the Kir channels may lead to an impaired clearance of K+ ions from the extracellular space and result in a stronger neuronal depolarisation. Two weeks after SE may be a reversal point. Spontaneous recurrent seizures (SRS) appeared at the two-week point, indicating that chronic epilepsy had occurred. Tenidap up-regulated expressions of both Kir2·3 channel mRNA and protein, which may help to maintain the resting membrane potential (RMP) and hyperpolarisation of the cells.Conclusions: Our results suggest that the down-regulation of the Kir2·3 channel expression might contribute to the pathogenesis of TLE, which may be ameliorated by the administration of tenidap.

No evidence for a role of the coding variant of the Toll-like receptor 4 gene in temporal lobe epilepsy

PurposeThere is evidence that inflammatory mechanisms play a role in the pathogenesis of temporal lobe epilepsy (TLE). Coding variants in Toll-like receptor 4 (TLR4) gene have been reported to be associated with inflammatory diseases. The aim of this study was to determine whether a functional polymorphism rs4986790 in the TLR4 gene is associated with susceptibility and clinical features of TLE. MethodsA total of 345 patients with TLE and 370 age-matched controls were genotyped using TaqMan Allelic Discrimination assays, on an Applied Biosystems PCR platform. ResultsThere was no significant difference in allele frequency or genotype of TLR4 between TLE patients and controls. Moreover, the clinical characteristics of these patients were unrelated to the presence of this polymorphism. ConclusionOur data suggest that rs4986790 in the TLR4 gene is unlikely to influence significantly the risk of developing TLE or its severity.

MRI changes and complement activation correlate with epileptogenicity in a mouse model of temporal lobe epilepsy

The complex pathogenesis of temporal lobe epilepsy includes neuronal and glial pathology, synaptic reorganization, and an immune response. However, the spatio-temporal pattern of structural changes in the brain that provide a substrate for seizure generation and modulate the seizure phenotype is yet to be completely elucidated. We used quantitative magnetic resonance imaging (MRI) to study structural changes triggered by status epilepticus (SE) and their association with epileptogenesis and with activation of complement component 3 (C3). SE was induced by injection of pilocarpine in CD1 mice. Quantitative diffusion-weighted imaging and T2 relaxometry was performed using a 16.4-Tesla MRI scanner at 3h and 1, 2, 7, 14, 28, 35, and 49days post-SE. Following longitudinal MRI examinations, spontaneous recurrent seizures and interictal spikes were quantified using continuous video-EEG monitoring. Immunohistochemical analysis of C3 expression was performed at 48h, 7days, and 4months post-SE. MRI changes were dynamic, reflecting different outcomes in relation to the development of epilepsy. Apparent diffusion coefficient changes in the hippocampus at 7days post-SE correlated with the severity of the evolving epilepsy. C3 activation was found in all stages of epileptogenesis within the areas with significant MRI changes and correlated with the severity of epileptic condition.

Relationship between genetic variant in pre-microRNA-146a and genetic predisposition to temporal lobe epilepsy: A case–control study

There is evidence that inflammatory mechanisms play a role in the pathogenesis of temporal lobe epilepsy (TLE). MicroRNAs (miRNAs), a class of small non-coding endogenous RNAs, which negatively regulate target gene expression, have shown different expression patterns in immune diseases. Recently, several miRNAs have been found to be differentially expressed in animal models of TLE. To understand the role of miRNAs in the molecular mechanisms of TLE, we sought to determine whether genetic variant rs2910164 in the pre-miR-146a gene could influence susceptibility to TLE in an Italian population sample. A cohort of 357 TLE patients and 543 healthy controls were genotyped for detection of this SNP using TaqMan Allelic Discrimination assays, on an Applied Biosystems PCR platform. Analysis of genotype or allelic frequencies between patients and controls showed no statistically significant differences (p=0.536 and p=0.361 respectively). Moreover, such variant did not influence the main clinical characteristics of TLE. In conclusion, our data suggest that the rs2910164 variant in the pre-miR-146a gene is unlikely to influence significantly the risk of developing TLE or its severity.

Up-Regulated Methyl CpG Binding Protein-2 in Intractable Temporal Lobe Epilepsy Patients and a Rat Model

Methyl CpG binding protein-2 (MeCP2) is a multifunctional nuclear protein, and regulates dendritic morphology, synaptic transmission, spontaneous neurotransmission, and short-term synaptic plasticity in the central nervous system. This study was designed to investigate the expression of MeCP2 mRNA and protein in intractable temporal lobe epilepsy (TLE) patients and an experimental animal model. MeCP2 expression was detected in 35 temporal neocortex tissue samples from patients with intractable TLE and 14histologically normal temporal lobe tissue samples from trauma patients without epilepsy by reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry and double-label immunofluorescence. In addition, the timing of MeCP2 expression was evaluated in the hippocampus and adjacent cortex of lithium chloride/pilocarpine-induced TLE rats and uninduced controls. MeCP2 was found to be expressed mainly in the nuclei of neurons, and not expressed in astrocytes. MeCP2 expression was significantly higher in the TLE patients and rats than in the control groups. Following seizures in the rat model, MeCP2 expression gradually increased in the hippocampus and adjacent cortex during the acute period (days 1 and 2) and the latent period (days 7 and 14), but decreased during the chronic period (days 30 and 60). Up-regulated expression of MeCP2 in intractable TLE patients and experimental animals suggested that MeCP2 may be involved in the pathogenesis of TLE.