Hippocampus, hippocampal sclerosis and epilepsy

Ganshuang granule plays a pharmacological role in anti-alcoholic and anti-hangover via regulating alcohol metabolism and affecting neurotransmitters

BACKGROUND

To explore the effect of Ganshuang granule on anti-alcoholic and anti-hangover and its potential mechanism.

METHODS

SPF SD rats' drunken model and SPF Kunming mice's hangover model were used as models.

RESULTS

Ganshuang granule could significantly reduce sleep time, the time to climb in mice, and significantly prolong the tolerance time and shorten sleep time in rats (p < 0.05). The blood ethanol concentration of rats in each administration group was lower than that in the model group at each time point (p < 0.05). Compared with the control group, the activities of ADH and ALDH in the liver of the model group were significantly decreased (p < 0.05); the content of DA and 5-HT in the striatum of the model group was significantly increased (p < 0.05); and the activity of AchE in the hippocampus was significantly decreased (p < 0.05). The above processes could be improved and regulated in the drug administration group. Compared with the control group, there was no significant difference between ADH and ALDH in the serum of the model group (p > 0.05). However, the activities of ADH and ALDH in the liver of drunk rats could be upregulated by Ganshuang granule (p < 0.05).

CONCLUSION

Ganshuang granule has the pharmacological effects of anti-alcoholic and anti-hangover, which is related to regulating the activities of ADH and ALDH in the liver, the contents of DA and 5-HT in striatum, and the activity of AchE in the hippocampus.

Hippocampal Glutamate Levels and Their Correlation With Subregion Volume in School-Aged Children With MRI-Negative Epilepsy: A Preliminary Study

BACKGROUND

Abnormal levels of glutamate constitute a key pathophysiologic mechanism in epilepsy. The use of glutamate chemical exchange saturation transfer (GluCEST) imaging to measure glutamate levels in pediatric epilepsy is rarely reported in research.

PURPOSE

To investigate hippocampal glutamate level variations in pediatric epilepsy and the correlation between glutamate and hippocampal subregional volumes.

STUDY TYPE

Cross-sectional, prospective.

SUBJECTS

A total of 38 school-aged pediatric epilepsy patients with structurally normal MRI as determined by at least two independent radiologists (60% males; 8.7 ± 2.5 years; including 20 cases of focal pediatric epilepsy [FE] and 18 cases of generalized pediatric epilepsy [GE]) and 17 healthy controls (HC) (41% males; 9.0 ± 2.5 years).

FIELD STRENGTH/SEQUENCE

3.0 T; 3D magnetization prepared rapid gradient echo (MPRAGE) and 2D turbo spin echo GluCEST sequences.

ASSESSMENT

The relative concentration of glutamate was calculated through pixel-wise magnetization transfer ratio asymmetry (MTRasym) analysis of the GluCEST data. Hippocampal subfield volumes were computed from MPRAGE data using FreeSurfer.

STATISTICAL TESTS

This study used t tests, one-way analysis of variance, Kruskal-Wallis tests, and Pearson correlation analysis. P < 0.05 was considered statistically significant.

RESULTS

The MTRasym values of both the left and right hippocampi were significantly elevated in GE (left: 2.51 ± 0.23 [GE] vs. 2.31 ± 0.12 [HCs], right: 2.50 ± 0.22 [GE] vs. 2.27 ± 0.22 [HCs]). The MTRasym values of the ipsilateral hippocampus were significantly elevated in FE (2.49 ± 0.28 [ipsilateral] vs. 2.29 ± 0.16 [HCs]). The MTRasym values of the ipsilateral hippocampus were significantly increased compared to the contralateral hippocampus in FE (2.49 ± 0.28 [ipsilateral] vs. 2.35 ± 0.34 [contralateral]). No significant differences in hippocampal volume were found between different groups (left hippocampus, P = 0.87; right hippocampus, P = 0.87).

DATA CONCLUSION

GluCEST imaging have potential for the noninvasive measurement of glutamate levels in the brains of children with epilepsy.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY: Stage 1.

Unraveling the neuroprotective effect of perampanel and lacosamide combination in the corneal kindling model for epilepsy in mice

BACKGROUND

Scientific evidence to guide clinicians on the use of different antiseizure drugs in combination therapy is either very limited or lacking. In this study, the impact of lacosamide and perampanel alone and in combination was tested in corneal kindling model in mice, which is a cost-effective mechanism for screening of antiseizure drugs.

METHODS

The impact of lacosamide (5 mg/kg) and perampanel (0.125 mg/kg) alone and their combination was tested in corneal kindling process (3-mA current for 3 s applied twice daily for consecutive 12 days) in male BALB/c mice. Post-kindling, mice were subjected to a battery of behavioral tests assessing anxiety, memory, and depression-like behaviors. Brain tissues were then harvested for analysis of oxidative stress biomarkers.

RESULTS

Our results showed that the combination therapy of lacosamide and perampanel was more effective in reducing seizure progression than monotherapy of these drugs. Animals treated with combination therapy showed significant behavioral improvements, as reduced anxiety and depression were noticed, and their cognitive abilities were notably better compared to animals of all other groups. Moreover, biochemical assays of isolated brains from combination-treated group revealed lesser amount of oxidative stress. In addition, outcomes of dual regime were comparable to the phenytoin in seizure control but showed superior benefits in mitigation of kindling-prompted behavioral dysfunction and oxidative stress.

CONCLUSIONS

This study suggests that the lacosamide and perampanel combination therapy worked noticeably better in halting the corneal kindling process in mice and improved the epilepsy-associated psychiatric disorders that might be due to antioxidant effects of both drugs.

Valproic acid attenuates the severity of astrogliosis in the hippocampus of animal models of temporal lobe epilepsy

Reactive astrogliosis is one of the most frequency neuropathological alterations in the hippocampus of animal models and patients with temporal lobe epilepsy (TLE). Valproic acid (VPA), a widely used antiepileptic drug (AED), acts by blocking ion channels and enhancing GABAergic activity. This study investigated the effects of VPA on hippocampal astrogliosis in a rat model of TLE. The results demonstrated that chronic administration of VPA at a dose of 200 mg/kg significantly reduced the severity of astrogliosis and ameliorated neuronal loss in the hippocampus at the early and middle stages post-status epilepticus (SE), while also improving cognitive impairments at the middle and late stages in KA-SE rats. Long-term administration of VPA at 400 mg/kg attenuated astrogliosis in the hippocampus at the middle stage post-SE, but lacked neuroprotective effects and exacerbated cognitive impairments at the late stage. These findings suggest that VPA at an appropriate dose could mitigate hippocampal astrogliosis, potentially offering a new antiepileptic mechanism for its long-term use.

Classification of Current Experimental Models of Epilepsy

INTRODUCTION

This article provides an overview of several experimental models, including in vivo, genetics, chemical, knock-in, knock-out, electrical, in vitro, and optogenetics models, that have been employed to investigate epileptogenesis. The present review introduces a novel categorization of these models, taking into account the fact that the most recent classification that gained widespread acceptance was established by Fisher in 1989. A significant number of such models have become virtually outdated.

OBJECTIVE

This paper specifically examines the models that have contributed to the investigation of partial seizures, generalized seizures, and status epilepticus.

DISCUSSION

A description is provided of the primary features associated with the processes that produce and regulate the symptoms of various epileptogenesis models. Numerous experimental epilepsy models in animals have made substantial contributions to the investigation of particular brain regions that are capable of inducing seizures. Experimental models of epilepsy have also enabled the investigation of the therapeutic mechanisms of anti-epileptic medications. Typically, animals are selected for the development and study of experimental animal models of epilepsy based on the specific form of epilepsy being investigated.

CONCLUSIONS

Currently, it is established that specific animal species can undergo epileptic seizures that resemble those described in humans. Nevertheless, it is crucial to acknowledge that a comprehensive assessment of all forms of human epilepsy has not been feasible. However, these experimental models, both those derived from channelopathies and others, have provided a limited comprehension of the fundamental mechanisms of this disease.

Ultrastructural Analysis of the Large Neuronal Perikarya in an Injured Dentate Nucleus Using an Experimental Model of Hyperthermia-Induced Convulsions: The First Qualitative and Quantitative Study

Background: Febrile seizures are a common form of convulsions in childhood, with poorly known cellular mechanisms. The objective of this pioneering study was to provide qualitative and quantitative ultrastructural research on the large neuronal perikarya in the cerebellar dentate nucleus (DN), using an experimental model of hyperthermia-induced seizures (HSs), comparable to febrile seizures in children. Methods: The study used young male Wistar rats, divided into experimental and control groups. The HSs were evoked by a hyperthermic water bath at 45 °C for 4 min for four consecutive days. Specimens (1 mm3) collected from the DN were routinely processed for transmission electron microscopy studies. Results: The ultrastructure of the large neurons in the DN affected by hyperthermic stress showed variously pronounced lesions in the perikarya, including total cell disintegration. The most pronounced neuronal lesions exhibited specific morphological signs of aponecrosis, i.e., dark cell degeneration ('dark neurons'). In close vicinity to the 'dark neurons', the aponecrotic bodies were found. The findings of this qualitative ultrastructural study correspond with the results of the morphometric analysis of the neuronal perikarya. Conclusions: Our results may constitute interesting comparative material for similar submicroscopic observations on large DN neurons in HS morphogenesis and, in the future, may help to find potential treatment targets to prevent febrile seizures or reduce recurrent seizures in children.

Association between serum apolipoprotein E and cognitive function in Chinese patients with temporal lobe epilepsy

OBJECTIVE

To investigate the effect of serum apolipoprotein E (APOE) levels on cognitive function in patients with temporal lobe epilepsy (TLE).

METHODS

Clinical data were collected from 190 subjects including 110 TLE patients and 80 healthy people. Cognitive function was assessed using the Addenbrooke's Cognitive Examination Revised (ACE-R) scale. Serum levels of APOE were measured using ELISA kits. Genotyping of APOE in peripheral blood was detected by microarray hybridization.

RESULTS

Patients with TLE had significantly lower ACE-R total score, memory and verbal fluency scores compared to the healthy group. Serum levels of APOE were significantly higher in TLE patients than in the healthy subjects. Serum APOE levels were significantly negatively correlated with ACE-R total score, memory and verbal fluency scores. The cognitive function score of TLE with APOE ε4 allele was lower than that of TLE without APOE ε4 allele.

SIGNIFICANCE

Our study showed that serum APOE levels were higher in TLE patients than in the healthy population. And serum APOE levels were associated with cognitive dysfunction in TLE patients. APOE ε4 allele carriers have poor cognitive function in TLE patients.

The effect of valproate on the amino acids, monoamines, and kynurenic acid concentrations in brain structures involved in epileptogenesis in the pentylenetetrazol-kindled rats

BACKGROUND

The study aimed to assess the influence of a single valproate (VPA) administration on inhibitory and excitatory neurotransmitter concentrations in the brain structures involved in epileptogenesis in pentylenetetrazol (PTZ)-kindled rats.

METHODS

Adult, male Wistar rats were kindled by repeated intraperitoneal (ip) injections of PTZ at a subconvulsive dose (30 mg/kg, three times a week). Due to the different times required to kindle the rats (18-22 injections of PTZ), a booster dose of PTZ was administrated 7 days after the last rats were kindled. Then rats were divided into two groups: acute administration of VPA (400 mg/kg) or saline given ip. The concentration of amino acids, kynurenic acid (KYNA), monoamines, and their metabolites in the prefrontal cortex, hippocampus, amygdala, and striatum was assessed by high-pressure liquid chromatography (HPLC).

RESULTS

It was found that a single administration of VPA increased the gamma-aminobutyric acid (GABA), tryptophan (TRP), 5-hydroxyindoleacetic acid (5-HIAA), and KYNA concentrations and decreased aspartate (ASP) levels in PTZ-kindled rats in the prefrontal cortex, hippocampus, amygdala and striatum.

CONCLUSIONS

Our results indicate that a single administration of VPA in the PTZ-kindled rats restored proper balance between excitatory (decreasing the level of ASP) and inhibitory neurotransmission (increased concentration GABA, KYNA) and affecting serotoninergic neurotransmission in the prefrontal cortex, hippocampus, amygdala, and striatum.

Increased thrombospondin-1 levels contribute to epileptic susceptibility in neonatal hyperthermia without seizures via altered synaptogenesis

Childhood febrile seizures (FS) represent one of the most common types of seizures and may lead to severe neurological damage and an increased risk of epilepsy. However, most children with fevers do not show clinical manifestations of convulsions, and the consequences of hyperthermia without seizures remain elusive. This study focused on hyperthermia not reaching the individual's seizure threshold (sub-FS stimulus). Changes in thrombospondin-1 (TSP-1) levels, synapses, seizure susceptibility, and seizure severity in subsequent FS were investigated in rats exposed to sub-FS stimuli. Pharmacological and genetic interventions were used to explore the role of TSP-1 in sub-FS-induced effects. We found that after sub-FS stimuli, the levels of TSP-1 and synapses, especially excitatory synapses, were concomitantly increased, with increased epilepsy and FS susceptibility. Moreover, more severe neuronal damage was found in subsequent FS. These changes were temperature dependent. Reducing TSP-1 levels by genetic intervention or inhibiting the activation of transforming growth factor-β1 (TGF-β1) by Leu-Ser-Lys-Leu (LSKL) led to lower synapse/excitatory synapse levels, decreased epileptic susceptibility, and attenuated neuronal injury after FS stimuli. Our study confirmed that even without seizures, hyperthermia may promote synaptogenesis, increase epileptic and FS susceptibility, and lead to more severe neuronal damage by subsequent FS. Inhibition of the TSP-1/TGF-β1 pathway may be a new therapeutic target to prevent detrimental sub-FS sequelae.

Epilepsy is more than a simple seizure disorder: Causal relationships between epilepsy and its comorbidities

This review draws connections between the pathogenesis of canine epilepsy and its most commonly recognised comorbidities: cognitive impairment (CI), attention deficit hyperactivity disorder (ADHD)-like behaviour, fear and anxiety. Uni/bidirectional causalities and the possibility of a common aetiology triggering both epilepsy and the associated diseases are considered. Research on this topic is sparse in dogs, so information has been gathered and assessed from human and laboratory animal studies. Anatomical structures, functional connections, disrupted neurotransmission and neuroinflammatory processes collectively serve as a common foundation for epilepsy and its comorbidities. Specific anatomical structures, especially parts of the limbic system, such as the amygdala and the hippocampus, are involved in generating seizures, as well as cognitive- and behavioural disorders. Furthermore, disturbances in inhibitory and excitatory neurotransmission influence neuronal excitability and networks, leading to underlying brain dysfunction. Functional magnetic resonance imaging (fMRI), interictal epileptiform discharges (IEDs), and electroencephalography (EEG) have demonstrated functional brain connections that are related to the emergence of both epilepsy and its various comorbidities. Neuroinflammatory processes can either cause or be a consequence of seizures, and inflammatory mediators, oxidative stress and mitochondrial dysfunction, can equally evoke mood disorders. The extensive relationships contributing to the development and progression of seizures and comorbid cognitive and behavioural conditions illustrate the complexity of the disease that is epilepsy.

Slack K+ channels limit kainic acid-induced seizure severity in mice by modulating neuronal excitability and firing

Mutations of the Na+-activated K+ channel Slack (KCNT1) are associated with terrible epilepsy syndromes that already begin in infancy. Here we report increased severity of acute kainic acid-induced seizures in adult and juvenile Slack knockout mice (Slack-/-) in vivo. Fittingly, we find exacerbation of cell death following kainic acid exposure in organotypic hippocampal slices as well as dissociated hippocampal cultures from Slack-/- in vitro. Furthermore, in cultured Slack-/- neurons, kainic acid-triggered Ca2+ influx and K+ efflux as well as depolarization-induced tetrodotoxin-sensitive inward currents are higher compared to the respective controls. This apparent changes in ion homeostasis could possibly explain altered action potential kinetics of Slack-/- neurons: steeper rise slope, decreased threshold, and duration of afterhyperpolarization, which ultimately lead to higher action potential frequencies during kainic acid application or injection of depolarizing currents. Based on our data, we propose Slack as crucial gatekeeper of neuronal excitability to acutely limit seizure severity.

Is depression in patients with temporal lobe epilepsy related to hippocampal sclerosis? A meta-analysis

OBJECTIVE

To systematically evaluate the association between hippocampal sclerosis (HS) and depression in patients with temporal lobe epilepsy (TLE) through a meta-analysis.

METHODS

Chinese and English databases, such as the China National Knowledge Infrastructure (CNKI), Chinese Scientific Journals (VIP), WanFang, the Chinese Biomedical Literature Service System (SinoMed), PubMed and the Web of Science, were searched.

RESULTS

Two evaluators independently screened the literature, extracted data and evaluated the risk of bias in the included studies in accordance with the inclusion and exclusion criteria. RevMan 5.1 was used to analyze the data. A total of 786 patients with epilepsy were included in the study, including 82 depressive patients with HS and 64 depressive patients without HS. The results showed that the TLE patients with HS were more likely to develop depression than those without HS (odds ratio (OR)= 2.14, 95% confidence interval (CI) [1.45, 3.16], Z = 3.85, p = 0.0001).

CONCLUSION

HS can be considered a high-risk factor for depression in patients with TLE, and the correlation is significant. However, the sample size included in the study was small; additional high-quality studies are needed in the future.

Parthanatos participates in glutamate-mediated HT22 cell injury and hippocampal neuronal death in kainic acid-induced status epilepticus rats

AIMS

Epileptic seizures or status epilepticus (SE) can cause hippocampal neuronal death, which has detrimental effects. Parthanatos, a new form of programmed cell death, is characterized by hyperactivation of poly (ADP-ribose) polymerase-1 (PARP-1), excessive synthesis of poly ADP-ribose polymer, mitochondrial depolarization, and nuclear translocation of apoptosis-inducing factor, observed in various neurodegenerative disorders but rarely reported in epilepsy. We aimed to investigate whether parthanatos participates in the mechanism of seizure-induced hippocampal neuronal death.

METHODS

Glutamate-mediated excitotoxicity cell model was used to study the mechanism of seizure-induced cell injury. Injection of kainic acid into the amygdala was used to establish the epileptic rat model. Corresponding biochemical tests were carried out on hippocampal tissues and HT22 cells following indicated treatments.

RESULTS

In vitro, glutamate time-dependently induced HT22 cell death, accompanied by parthanatos-related biochemical events. Pretreatment with PJ34 (PARP-1 inhibitor) or small interfering RNA-mediated PARP-1 knockdown effectively protected HT22 cells against glutamate-induced toxic effects and attenuated parthanatos-related biochemical events. Application of the antioxidant N-acetylcysteine (NAC) rescued HT22 cell death and reversed parthanatos-related biochemical events. In vivo, PJ34 and NAC afforded protection against SE-induced hippocampal neuronal damage and inhibited parthanatos-related biochemical events.

CONCLUSION

Parthanatos participates in glutamate-induced HT22 cell injury and hippocampal neuronal damage in rats following epileptic seizures. ROS might be the initiating factor during parthanatos.

A mathematical model of neuroimmune interactions in epileptogenesis for discovering treatment strategies

The development of epilepsy (epileptogenesis) involves a complex interplay of neuronal and immune processes. Here, we present a first-of-its-kind mathematical model to better understand the relationships among these processes. Our model describes the interaction between neuroinflammation, blood-brain barrier disruption, neuronal loss, circuit remodeling, and seizures. Formulated as a system of nonlinear differential equations, the model reproduces the available data from three animal models. The model successfully describes characteristic features of epileptogenesis such as its paradoxically long timescales (up to decades) despite short and transient injuries or the existence of qualitatively different outcomes for varying injury intensity. In line with the concept of degeneracy, our simulations reveal multiple routes toward epilepsy with neuronal loss as a sufficient but non-necessary component. Finally, we show that our model allows for in silico predictions of therapeutic strategies, revealing injury-specific therapeutic targets and optimal time windows for intervention.

•

A dynamical systems model describes the development of epilepsy after different injuries

•

Simulation results are in agreement with data from three animal models

•

Model shows degeneracy: multiple distinct but linked mechanisms cause epileptogenesis

•

Framework permits studying the effects of therapeutic interventions in silico

[Magnetic resonance imaging findings in 143 epileptic cats]

OBJECTIVE

Epilepsy is one of the more common chronic neurological diseases in cats in which MRI plays a key role in the diagnostic work-up. Hippocampal MRI changes are common in cats, however it is unclear whether these changes represent the reason or the consequence of the disease.The goal of the present study was the retrospective analysis of the MRI findings in a large cohort of epileptic cats.

MATERIAL AND METHODS

In total, 143 cats of 3 age groups (< 1 year, 1-6 years, and > 6 years) were included in the study. MRI findings were divided into 4 categories: normal, with extrahippocampal lesions, and hippocampal signal alterations with or without contrast enhancement. The prevalence and frequency of these MRI findings in the age groups were examined using chi-quadrat test and nominal regression model.

RESULTS

In approximately one half of the cats (49 %), MRI displayed normal findings. Extrahippocampal changes occurred in 18 % of the animals. Hippocampal alterations were present in 33 % of the cats. Hippocampal sclerosis was found histopathologically in all four MRI categories.

CONCLUSION AND CLINICAL RELEVANCE

Brain MRI was normal in approximately 50 % of the epileptic cats. Extrahippocampal changes are expected mostly in cats older than 6 years. The etiology of the hippocampal alterations is unclear in most cases. Further investigations are needed for a better understanding of the hippocampal signal alterations.

The role of astrocytes in epileptic disorders

Epilepsy affects about 1% of the population and approximately 30% of epileptic patients are resistant to current antiepileptic drugs. As a hallmark in epileptic tissue, many of the epileptic patients show changes in glia morphology and function. There are characteristic changes in different types of glia in different epilepsy models. Some of these changes such as astrogliosis are enough to provoke epileptic seizures. Astrogliosis is well known in mesial temporal lobe epilepsy (MTLE), the most common form of refractory epilepsy. A better understanding of astrocytes alterations could lead to novel and efficient pharmacological approaches for epilepsy. In this review, we present the alterations of astrocyte morphology and function and present some instances of targeting astrocytes in seizure and epilepsy.

The methods of vibrational microspectroscopy reveals long-term biochemical anomalies within the region of mechanical injury within the rat brain

Traumatic brain injury (TBI), meaning functional or structural brain damage which appear as a result of the application of the external physical force, constitutes the main cause of death and disability of individuals and a great socioeconomic problem. To search for the new therapeutic strategies for TBI, better knowledge about posttraumatic pathological changes occurring in the brain is necessary. Therefore in the present paper the Fourier transform infrared microspectroscopy and Raman microscopy were used to examine local and remote biochemical changes occurring in the rat brain as a result of focal cortex injury. The site of the injury and the dorsal part of the hippocampal formation together with the above situated cortex and white matter were the subject of the study. The topographic and quantitative biochemical analysis followed with the statistical study using principal component analysis showed significant biomolecular anomalies within the lesion site but not in the area of the dorsal hippocampal formation and in the above situated white matter and cortex. The observed intralesional anomalies included significantly decreased accumulation of lipids and their structural changes within the place of injury. Also the levels of compounds containing phosphate and carbonyl groups were lower within the lesion site comparing to the surrounding cortex. The opposite relation was, in turn, found for the bands characteristic to proteins and cholesterol/cholesterol esters.

Influence of Topiramate on the Synaptic Endings of the Temporal Lobe Neocortex in an Experimental Model of Hyperthermia-Induced Seizures: An Ultrastructural Study

The objective of this pioneering study was to assess potentially neuroprotective properties of topiramate (TPM), a broad spectrum and newer-generation antiepileptic used against damage to synaptic endings of the temporal lobe neocortex in experimental hyperthermia-induced seizures (HS). TPM (80 mg/kg b.m.) was administered in young male Wistar rats with an intragastric tube before and immediately after HS. Specimens (1 mm³) collected from the neocortex, fixed via transcardial perfusion with paraformaldehyde and glutaraldehyde solution, were routinely processed for transmission-electron microscopic study, i.e., for descriptive and morphometric analysis. The ultrastructure of neocortical neuropil components affected by hyperthermic stress showed distinct swelling of pre and post-synaptic axodendritic and axospinal endings, including total disintegration. Mitochondria were markedly damaged in synaptic structures. Axoplasm of presynaptic boutons contained a decreased number of synaptic vesicles. Synaptic junctions showed active zone-shortening. Preventive administration of TPM before HS induction demonstrated neuroprotective effects against synaptic damage in approximately 1/4 of these structures. Interestingly, beneficial effects on synapsis morphology were more common in perivascular zones close to well-preserved capillaries. They were demonstrated by smaller swelling of both presynaptic and postsynaptic parts, well-preserved mitochondria, an increased number and regular distribution of synaptic vesicles within axoplasm, and a significantly increased synaptic active zones. However, topiramate used directly after HS was ineffective in the prevention of hyperthermia-evoked synaptic injury. Our findings support the hypothesis that topiramate applied before HS can protect some neocortical synapses via the vascular factor by enhancing blood-brain barrier components and improving the blood supply of gray matter in the temporal lobe, which may be significant in febrile seizure-prevention in children.

Life and death in the hippocampus: What's bad?

The hippocampal formation is crucial for the generation and regulation of several brain functions, including memory and learning processes; however, it is vulnerable to neurological disorders, such as epilepsy. Temporal lobe epilepsy (TLE), the most common type of epilepsy, changes the hippocampal circuitry and excitability, under the contribution of both neuronal degeneration and abnormal neurogenesis. Classically, neurodegeneration affects sensitive areas of the hippocampus, such as dentate gyrus (DG) hilus, as well as specific fields of the Ammon's horn, CA3, and CA1. In addition, the proliferation, migration, and abnormal integration of newly generated hippocampal granular cells (GCs) into the brain characterize TLE neurogenesis. Robust studies over the years have intensely discussed the effects of death and life in the hippocampus, though there are still questions to be answered about their possible benefits and risks. Here, we review the impacts of death and life in the hippocampus, discussing its influence on TLE, providing new perspectives or insights for the implementation of new possible therapeutic targets. This article is part of the Special Issue "NEWroscience 2018".

Adipose-derived stem cell transplantation improves learning and memory via releasing neurotrophins in rat model of temporal lobe epilepsy

Epilepsy is a common neurological disease and its most common type is temporal lobe epilepsy (TLE). Novel therapeutics is needed as many TLE patients are resistant to treatments like anticonvulsants or temporal lobectomy. Stem cell therapy has great promise in regeneration medicine. In the current study, we tried to investigate the potential protective effects of adipose-derived stem cell (ADSC) transplantation in epileptic rats. Epilepsy model was established by intra-hippocampal injection of kainic acid (KA) in rats. ADSCs were isolated, differentiated and transplanted into hippocampus of KA rats. There were three groups of rats: normal control group receiving saline injection and no transplantation, KA + sham group receiving KA injection and sham transplantation surgery and KA + transplantation group receiving KA injection and ADSC transplantation. We found that ADSCs were highly positive for CD44, CD90, CD29 and CD105, and neural differentiation induced the expression of neuronal markers like Tuj1, MAP2, NeuN and PSD-95. EEG recording showed that KA induced seizure activity while ADSC transplantation inhibited seizure activity. In training session of Morris water maze task, KA injection impaired the learning capacity of rats while ADSC transplantation restored the learning capacity at 2-week or 2-month post transplantation. In probe session of Morris water maze task, KA injection impaired the memory of rats while ADSC transplantation restored the memory at 2-week or 2-month post transplantation. Transplanted ADSCs released BDNF, NT3 and NT4. Pro-apoptotic BAX was reduced while anti-apoptotic BCL-2 and BCL-xL were increased in hippocampus post ADSC transplantation. Our study suggests that ADSC transplantation inhibits KA-induced seizures and improves the learning and memory function of epileptic rats.

Neuroprotective and anticonvulsant effects of sinomenine in kainate rat model of temporal lobe epilepsy: Involvement of oxidative stress, inflammation and pyroptosis

Oxidative stress, inflammation and pyroptosis are three of the most important mechanisms in the pathophysiology of temporal lobe epilepsy (TLE). Most people with TLE are refractory to the existing drugs. Sinomenine has shown neuroprotective effects through counteracting oxidative stress, inflammation and pyroptosis. In this study, we evaluated the effect of sinomenine on seizure behavior, oxidative stress, inflammation and pyroptosis markers in addition to its neuroprotective potential in intrahippocampal kainate-induced rat model of TLE. For this purpose, male rats (n = 60) were randomly divided into five groups, i.e., sham, kainate (lesion) with an intrahippocampal injection of kainate, kainate groups receiving sinomenine at doses of 30 or 50 mg/kg, and kainate group receiving valproic acid at a dose of 200 mg/kg (as the positive control). Our obtained data showed that sinomenine administration at a dose of 50 mg/kg can significantly decreases severity of seizures and incidence of status epilepticus (SE), hippocampal aberrant MFS and DNA fragmentation and prevents reduction of neuronal density. It also significantly restored level of ROS, MDA, HO-1 and SOD but its effect on GSH level was not significant. Additionally, sinomenine at a dose of 50 mg/kg partially counteracted the increase of NF-κB, TLR 4, TNFα, GFAP and caspase 1. These results suggest that sinomenine has anticonvulsant and neuroprotective effects by reducing hippocampal oxidative stress, inflammation, pyroptosis and apoptosis in intrahippocampal kainate model of TLE.

Changes in excitatory and inhibitory receptor expression and network activity during induction and establishment of epilepsy in the rat Reduced Intensity Status Epilepticus (RISE) model

The RISE model is an effective system to study the underlying molecular and cellular mechanisms involved in the initiation and maintenance of epilepsy in vivo. Here we profiled the expression of excitatory and inhibitory neurotransmitter receptor subunits and synaptic scaffolding proteins in the hippocampus and temporal lobe and compared these changes with alterations in network activity at specific timepoints during epileptogenesis. Significant changes occurred in all of the ionotropic glutamate receptor subunits tested during epilepsy induction and progression and the profile of these changes differed between the hippocampus and temporal lobe. Notably, AMPAR subunits were dramatically decreased during the latent phase of epilepsy induction, matched by a profound decrease in the network response to kainate application in the hippocampus. Moreover, decreases in the GABAAβ3 subunit are consistent with a loss of inhibitory input contributing to the perturbation of excitatory/inhibitory balance and seizure generation. These data highlight the synaptic reorganisation that mediates the relative hypoexcitability prior to the manifestation of seizures and subsequent hyperexcitability when spontaneous seizures develop. These patterns of changes give new insight into the mechanisms underpinning epilepsy and provide a platform for future investigations targeting particular receptor subunits to reduce or prevent seizures.

Impact of epilepsy duration, seizure control and EEG abnormalities on cognitive impairment in drug-resistant epilepsy patients

Cognitive impairment frequently occurs in epilepsy patients. Patients with drug-resistant epilepsy (DRE) have poor drug responsivity and higher seizure frequency which consequently lead to brain damage and may have implications on cognitive status. In the present study, we assessed a frequency and degree of cognitive impairment in 52 patients with drug-sensitive epilepsy (DSE) and 103 DRE patients at three time points (baseline, after 12 and 18 months). Degree of cognitive decline was assessed with Montreal Cognitive Assessment (MoCA) scale. We examined the possible correlation between demographic and clinical characteristics and cognitive deterioration in epilepsy patients. Patients in the DRE group had significantly lower MoCA score than patients in the DSE group at baseline (28.83 ± 2.05 vs. 29.69 ± 0.61, p = 0.003), after 12 months (27.36 ± 2.40 vs. 29.58 ± 1.22, p = 0.000) and 18 months (26.86 ± 2.73 vs. 29.33 ± 1.47, p = 0.000). Patients with DRF epilepsy had significantly lower MoCA score than patients with DSF epilepsy at three time points (28.71 ± 2.48 vs. 29.86 ± 0.35, p = 0.015; 27.22 ± 2.72 vs. 29.52 ± 1.37, p = 0.000; 26.80 ± 2.99 vs. 29.31 ± 1.56, p = 0.000). After 12 and 18 months of follow-up, patients with DRG epilepsy had significantly lower MoCA score than patients with DSG epilepsy (27.52 ± 2.01 vs. 29.65 ± 1.02, p = 0.000; 26.94 ± 2.43 vs. 29.35 ± 1.40, p = 0.000). Illness duration negatively correlated with cognitive status (p = 0.005); seizure control and EEG findings positively correlated with MoCA score (p = 0.000). Illness duration, seizure control, drug responsivity, and EEG findings are significant predictors of MoCA score (p < 0.05). Clinicians have to pay attention to patients with drug-resistant epilepsy and concepts of aggressive treatment to minimize the adverse effects of epilepsy on cognition.

Anxiety-like features and spatial memory problems as a consequence of hippocampal SV2A expression

The Synaptic Vesicle Protein 2A (SV2A) is a transmembrane protein whose presence is reduced both in animal models and in patients with chronic epilepsy. Besides its implication in the epileptic process, the behavioural consequences of the changes in its expression remain unclear. The purpose of our research is to better understand the possible role(s) of this protein through the phenotype of cKO (Grik4 Cre+/-, SV2A lox/lox) mice, male and female, which present a specific decrease of SV2A expression levels in the hippocampal glutamatergic neurons but without any epileptic seizures. In this study, we compare the cKO mice with cHZ (Grik4 Cre+/-, SV2A lox/+) and WT (Grik4 Cre+/+, SV2A lox/lox) mice through a battery of tests, used to evaluate different features: the anxiety-related features (Elevated Plus Maze), the locomotor activity (Activity Chambers), the contextual fear-related memory (Contextual Fear Conditioning), and the spatial memory (Barnes Maze). Our results showed statistically significant differences in the habituation to a new environment, an increase in the anxiety levels and spatial memory deficit in the cHZ and cKO groups, compared to the WT group. No statistically significant differences due to the genotype appeared in the spontaneous locomotor activity or the fear-linked memory. However, sexual differences were observed in this last feature. These results highlight not only an important role of the SV2A protein in the cognitive and anxiety problems typically encountered in epileptic patients, but also a possible role in the symptomatology of other neurodegenerative diseases, such as the Alzheimer’s disease.

Rifampicin ameliorates lithium-pilocarpine-induced seizures, consequent hippocampal damage and memory deficit in rats: Impact on oxidative, inflammatory and apoptotic machineries

Epilepsy is one of the serious neurological sequelae of bacterial meningitis. Rifampicin, the well-known broad spectrum antibiotic, is clinically used for chemoprophylaxis of meningitis. Besides its antibiotic effects, rifampicin has been proven to be an effective neuroprotective candidate in various experimental models of neurological diseases. In addition, rifampicin was found to have promising antioxidant, anti-inflammatory and anti-apoptotic effects. Herein, we investigated the anticonvulsant effect of rifampicin at experimental meningitis dose (20 mg/kg, i.p.) using lithium-pilocarpine model of status epilepticus (SE) in rats. Additionally, we studied the effect of rifampicin on seizure induced histopathological, neurochemical and behavioral abnormalities. Our study showed that rifampicin pretreatment attenuated seizure activity and the resulting hippocampal insults marked by hematoxylin and eosin. Markers of oxidative stress, neuroinflammation and apoptosis were evaluated, in the hippocampus, 24 h after SE induction. We found that rifampicin pretreatment suppressed oxidative stress as indicated by normalized malondialdehyde and glutathione levels. Rifampicin pretreatment attenuated SE-induced neuroinflammation and decreased the hippocampal expression of interleukin-1β, tumor necrosis factor-α, nuclear factor kappa-B, and cyclooxygenase-2. Moreover, rifampicin mitigated SE-induced neuronal apoptosis as indicated by fewer positive cytochrome c immunostained cells and lower caspase-3 activity in the hippocampus. Furthermore, Morris water maze testing at 7 days after SE induction showed that rifampicin pretreatment can improve cognitive dysfunction. Therefore, rifampicin, currently used in the management of meningitis, has a potential additional advantage of ameliorating its epileptic sequelae.

Correlation between tumor necrosis factor alpha mRNA and microRNA-155 expression in rat models and patients with temporal lobe epilepsy

Accumulative evidence demonstrates that there is an inseparable connection between inflammation and temporal lobe epilepsy (TLE). Some recent studies have found that the multifunctional microRNA-155 (miR-155) is a key regulator in controlling the neuroinflammatory response of TLE rodent animals and patients. The aim of the present study was to investigate the dynamic expression pattern of tumor necrosis factor alpha (TNF-α) as a pro-inflammatory cytokine and miR-155 as a posttranscriptional inflammation-related miRNA in the hippocampus of TLE rat models and patients. We performed real-time quantitative PCR (qRT-PCR) on the rat hippocampus 2 h, 7 days, 21 days and 60 days following kainic acid-induced status epilepticus (SE) and on hippocampi obtained from TLE patients and normal controls. To further characterize the relationship between TNF-α and miR-155, we examined the effect of antagonizing miR-155 on TNF-α secretion using its antagomir. Here, we found that TNF-α secretion and miR-155 expression levels were correlated after SE. The expression of TNF-α reached peak levels in the acute phase (2h post-SE) of seizure and then gradually decreased; however, it rose again in the chronic phase (60 days post-SE). miR-155 expression started to increase 2 h post-SE, reached peak levels in the latent phase (7 days post-SE) of seizure and then gradually decreased. The variation in the trend of miR-155 lagged behind that of TNF-α. In patients with TLE, the expression levels of both TNF-α and miR-155 were also significantly increased. Furthermore, antagonizing miR-155 inhibited the production of TNF-α in the hippocampal tissues of TLE rat models. Our findings demonstrate a critical role for miR-155 in the physiological regulation of the TNF-α pro-inflammatory response and elucidate the role of neuroinflammation in the pathogenesis of TLE. Therefore, regulation of the miR-155/TNF-α axis may be a new therapeutic target for TLE.

The role of the microRNA-146a/complement factor H/interleukin-1β-mediated inflammatory loop circuit in the perpetuate inflammation of chronic temporal lobe epilepsy

Increasing evidence indicates that neuroinflammation plays a crucial role in the pathogenesis of temporal lobe epilepsy (TLE). However, it is unclear how the perpetuate inflammation develops. Some recent studies have suggested the possible involvement of microRNA-146a (miR-146a) in the modulation of inflammatory signaling occurring in TLE. To understand how miR-146a modulates inflammatory signaling in TLE, we investigated the role of interleukin-1β (IL-1β), miR-146a and human complement factor H (CFH) in the perpetuate inflammation in rat models of chronic TLE and U251 cells. We found that enhancive miR-146a could upregulate the expression of IL-1β and downregulate the expression of CFH, whereas reductive miR-146a could downregulate the expression of IL-1β and upregulate the expression of CFH, in hippocampi of chronic TLE rat models. Meanwhile, enhancive miR-146a could increase the abnormal wave forms in the chronic TLE rat models. Additionally, enhancive IL-1β could feedback downregulate the expression of CFH, upregulate the expression of miR-146a and increase the abnormal wave forms in chronic TLE rat models. After CFH gene knockdown in U251 cells, enhancive miR-146a did not upregulate the expression of IL-1β. In summary, this study shows that enhancive miR-146a can upregulate the inflammatory factor IL-1β in chronic TLE by downregulating CFH, and that upregulation of IL-1β plays an important feedback-regulating role in the expression of miR-146a and CFH, forming a miR-146a–CFH–IL-1β loop circuit that initiates a cascade of inflammation and then leads to the perpetuate inflammation in TLE. Therefore, modulation of the miR-146a–CFH–IL-1β loop circuit could be a novel therapeutic target for TLE.

Summary: The microRNA-146a–complement factor H–interleukin-1β loop circuit might initiate a cascade of inflammation, leading to the perpetuate inflammation in temporal lobe epilepsy.

Changes in the Expression of AQP4 and AQP9 in the Hippocampus Following Eclampsia-Like Seizure

Eclampsia is a hypertensive disorder of pregnancy that is defined by the new onset of grand mal seizures on the basis of pre-eclampsia. Until now, the mechanisms underlying eclampsia were poorly understood. Brain edema is considered a leading cause of eclamptic seizures; aquaporins (AQP4 and AQP9), the glial water channel proteins mainly expressed in the nervous system, play an important role in brain edema. We studied AQP4 and AQP9 expression in the hippocampus of pre-eclamptic and eclamptic rats in order to explore the molecular mechanisms involved in brain edema. Using our previous animal models, we found several neuronal deaths in the hippocampal CA1 and CA3 regions after pre-eclampsia and that eclampsia induced more neuronal deaths in both areas by Nissl staining. In the current study, RT-PCR and Western blotting data showed significant upregulation of AQP4 and AQP9 mRNA and protein levels after eclamptic seizures in comparison to pre-eclampsia and at the same time AQP4 and AQP9 immunoreactivity also increased after eclampsia. These findings showed that eclamptic seizures induced cell death and that upregulation of AQP4 and AQP9 may play an important role in this pathophysiological process.

Glucagon-like Peptide-1 (GLP-1) and neurotransmitters signaling in epilepsy: An insight review

Epilepsy is one of the most prevalent neurological disorder affecting more than 50 million people worldwide. Numerous studies have suggested that an imbalance in glutamatergic (excitatory) and GABAergic (inhibitory) neurotransmitter system is one of the dominating pathophysiological mechanisms underlying the occurrence and progression of seizures. Further, this alteration in GABAergic and glutamatergic system disrupts the delicate balance of other neurotransmitters system in the brain. Emerging strides have documented the protective role of GLP-1 signaling on altered neurotransmitters signaling in Epilepsy and associated co-morbidities. GLP-1 is neuropeptide and synthesized by preproglucagon (PPG) neurons in the brain. GLP-1 receptors are widely distributed throughout the brain including hippocampus (CA3 and CA1 region) and implicated in various neurological disorders like Epilepsy. A complete understanding of alteration in neurotransmitters signaling will provide essential insight into the basic pathogenic mechanisms of epilepsy and may uncover novel targets for future drug therapies. Presently, treatment of epilepsy is palliative in nature, providing only symptomatic relief to patients. The apparent or traditional approach of treating epileptic subjects with anti-epileptic drugs is associated with variety of adverse effects. Therefore, alternative approaches that can restore altered neurotransmitter signaling are being tried and adopted. Present review is an attempt to highlight the emerging protective role of GLP-1 signaling on altered neurotransmitters signaling in epilepsy. Authors have made significant efforts to discuss effect of various GLP-1 analogs on various neurotransmitters system and associated molecular and cellular pathways as a potential drug target for the management of epilepsy and associated co-morbidities. This article is part of the Special Issue entitled 'Metabolic Impairment as Risk Factors for Neurodegenerative Disorders.'

Neuroanatomical Changes in Brain Structures Related to Cognition in Epilepsy: An Update

Understanding the microanatomical changes in brain structures is necessary for developing innovative therapeutic approaches to prevent/delay the cognitive impairment in epilepsy. We review here the microanatomical changes in the brain structures related to cognition in epilepsy. Here, we have presented the changes in major brain structures related to cognition, which helps the clinicians understand epilepsy more clearly and also helps researchers develop new treatment procedures.

SRF modulates seizure occurrence, activity induced gene transcription and hippocampal circuit reorganization in the mouse pilocarpine epilepsy model

A hallmark of temporal lobe epilepsy (TLE) is hippocampal neuronal demise and aberrant mossy fiber sprouting. In addition, unrestrained neuronal activity in TLE patients induces gene expression including immediate early genes (IEGs) such as Fos and Egr1.

We employed the mouse pilocarpine model to analyze the transcription factor (TF) serum response factor (SRF) in epileptogenesis, seizure induced histopathology and IEG induction. SRF is a neuronal activity regulated TF stimulating IEG expression as well as nerve fiber growth and guidance. Adult conditional SRF deficient mice (Srf^CaMKCreERT2) were more refractory to initial status epilepticus (SE) acquisition. Further, SRF deficient mice developed more spontaneous recurrent seizures (SRS). Genome-wide transcriptomic analysis uncovered a requirement of SRF for SE and SRS induced IEG induction (e.g. Fos, Egr1, Arc, Npas4, Btg2, Atf3). SRF was required for epilepsy associated neurodegeneration, mossy fiber sprouting and inflammation. We uncovered MAP kinase signaling as SRF target during epilepsy. Upon SRF ablation, seizure evoked induction of dual specific phosphatases (Dusp5 and Dusp6) was reduced. Lower expression of these negative ERK kinase regulators correlated with altered P-ERK levels in epileptic Srf mutant animals.

Overall, this study uncovered an SRF contribution to several processes of epileptogenesis in the pilocarpine model.

Anticonvulsant Effects of the Hydroalcoholic Extract of Alpinia officinarum Rhizomesin Mice: Involvement of Benzodiazepine and Opioid Receptors

Background and Purpose

Epilepsy is one of the most common serious neurological conditions. The current therapeutic treatment of epilepsy with modern antiepileptic drugs is associated with side effects, dose-related and chronic toxicity, and teratogenic effects and in approximately 30% of the patients is ineffective. Alpinia officinarum is used in Iranian traditional medicine for treatment of different diseases like back pain and seizure.

Methods

In this study, anticonvulsant effects of hydroalcoholic extract of Alpinia officinarum rhizomes were examined by using pentylentetrazole (PTZ) model in mice. Alpinia officinarum rhizomes extract (200, 400 and 600 mg/kg), diazepam (1 mg/kg) and normal saline (10 mL/kg) were injected (ip) 30 minutes before PTZ (90 mg/kg, ip). The time taken before the onset of clonic convulsions, the duration of colonic convulsions, and the percentage of seizure and mortality protection were recorded. For further clarification of the mechanism of action for Alpinia officinarum, flumazenil (2 mg/kg, ip) and naloxone (5 mg/kg, ip) were also injected 5 minutes before Alpinia officinarum extract.

Results

Alpinia officinarum extract at the doses of 200 and 400 mg/kg prolonged the time of onset of seizure and decreased the duration of seizures compared to control (saline) group (p < 0.05). At the dose of 600 mg/kg, percentage of seizure protection was 16.66%. Naloxone and flumazenil could suppress anticonvulsant effects of Alpinia officinarum.

Conclusions

It seems that Alpinia officinarum could be a good candidate and be useful for seizure control and treatment, and in these effects, opioid and benzodiazepine receptors might probably be involved.

Unfavorable effect of levetiracetam on cultured hippocampal neurons after hyperthermic injury

BACKGROUND

The aim of this study was to examine the viability of neurons and the putative neuroprotective effects of second-generation antiepileptic drug, levetiracetam (LEV), on cultured hippocampal neurons injured by hyperthermia.

METHODS

Primary cultures of rat's hippocampal neurons at 7 day in vitro (DIV) were incubated in the presence or absence of LEV in varied concentrations under hyperthermic conditions. Cultures were heated in a temperature of 40 °C for 24 h or in a temperature of 41 °C for 6 h. Flow cytometry with Annexin V/PI staining as well as fluorescent microscopy assay were used for counting and establishing neurons as viable, necrotic or apoptotic. Additionally, the release of lactate dehydrogenase (LDH) to the culture medium, as a marker of cell death, was evaluated. Assessment was performed after 9DIV and 10 DIV.

RESULTS

Incubation of hippocampal cultures in hyperthermic conditions resulted in statistically significant increase in the number of injured neurons when compared with non-heated control cultures. Intensity of neuronal destruction was dependent on temperature-value. When incubation temperature 40 °C was used, over 80% of the population of neurons remained viable after 10 DIV. Under higher temperature 41 °C, only less than 60% of neurons were viable after 10 DIV. Both apoptotic and necrotic pathways of neuronal death induced by hyperthermia were confirmed by Annexin V/PI staining.

CONCLUSIONS

LEV showed no neuroprotective effects in the current model of hyperthermia in vitro. Moreover, drug, especially when used in higher concentrations, exerted unfavorable intensification of aponecrosis of cultured hippocampal neurons.

Human astrocytes in the diseased brain

Astrocytes are key active elements of the brain that contribute to information processing. They not only provide neurons with metabolic and structural support, but also regulate neurogenesis and brain wiring. Furthermore, astrocytes modulate synaptic activity and plasticity in part by controlling the extracellular space volume, as well as ion and neurotransmitter homeostasis. These findings, together with the discovery that human astrocytes display contrasting characteristics with their rodent counterparts, point to a role for astrocytes in higher cognitive functions. Dysfunction of astrocytes can thereby induce major alterations in neuronal functions, contributing to the pathogenesis of several brain disorders. In this review we summarize the current knowledge on the structural and functional alterations occurring in astrocytes from the human brain in pathological conditions such as epilepsy, primary tumours, Alzheimer's disease, major depressive disorder and Down syndrome. Compelling evidence thus shows that dysregulations of astrocyte functions and interplay with neurons contribute to the development and progression of various neurological diseases. Targeting astrocytes is thus a promising alternative approach that could contribute to the development of novel and effective therapies to treat brain disorders.

Smad anchor for receptor activation contributes to seizures in temporal lobe epilepsy

PURPOSE

Smad anchor for receptor activation (SARA) is an important regulator of transforming growth factor β (TGF-β) signaling by recruiting Smad2/3 to TGF-β receptors. Although TGF-β signaling is critically involved in epileptogenesis, whether SARA activation is sufficient to facilitate TGF-β pathway to regulate epilepsy remains unknown.

METHODS

The expression of SARA and downstream Phospho-Smad3 (p-Smad3) was examined in rats with pilocarpine induced epilepsy. Additionally, knockdown of SARA was performed via recombinant lentiviral vector in the pilocarpine-induced rats.

RESULTS

Here we show that expressions of SARA and p-Smad3 are increased in the hippocampus as rats subjected to pilocarpine-induced status epilepticus (SE). Both SARA and p-Smad3 are also upregulated in the temporal cortex of epileptic rats. Furthermore, SARA mRNA levels reach peak as early as 6 hr following SE onset and remain elevated in the chronic phase. Transfection of recombinant lentiviral shRNA targeting SARA knocks down SARA expression, attenuates TGF-β/p-Smad3 signaling in the hippocampus, and postpones the SE onset.

CONCLUSION

Our results demonstrate that SARA/Smad3 pathway contributes to mechanism of seizure and SARA in TGF-β signaling may be a potential therapeutic target for epilepsy.

Disease-modifying effect of intravenous immunoglobulin in an experimental model of epilepsy

Novel therapies that prevent or modify the development of epilepsy following an initiating brain insult could significantly reduce the burden of this disease. In light of evidence that immune mechanisms play an important role in generating and maintaining the epileptic condition, we evaluated the effect of a well-established immunomodulatory treatment, intravenous immunoglobulin (IVIg), on the development of epilepsy in an experimental model of epileptogenesis. In separate experiments, IVIg was administered either before (pre-treatment) or after (post-treatment) the onset of pilocarpine status epilepticus (SE). Our results show that both pre- and post-treatment with IVIg attenuated acute inflammation in the SE model. Specifically, IVIg reduced local activation of glial cells, complement system activation, and blood-brain barrier damage (BBB), which are all thought to play important roles in the development of epilepsy. Importantly, post-treatment with IVIg was also found to reduce the frequency and duration of subsequent spontaneous recurrent seizures as detected by chronic video-electroencephalographic (video-EEG) recordings. This finding supports a novel application for IVIg, specifically its repurposing as a disease-modifying therapy in epilepsy.

Role of the purinergic signaling in epilepsy

Adenine nucleotides and adenosine are signaling molecules that activate purinergic receptors P1 and P2. Activation of A1 adenosine receptors has an anticonvulsant action, whereas activation of A2A receptors might initiate seizures. Therefore, a significant limitation to the use of A1 receptor agonists as drugs in the CNS might be their peripheral side effects. The anti-epileptic activity of adenosine is related to its increased concentration outside the cell. This increase might result from the inhibition of the equilibrative nucleoside transporters (ENTs). Moreover, the implantation of implants or stem cells into the brain might cause slow and persistent increases in adenosine concentrations in the extracellular spaces of the brain. The role of adenosine in seizure inhibition has been confirmed by results demonstrating that in patients with epilepsy, the adenosine kinase (ADK) present in astrocytes is the only purine-metabolizing enzyme that exhibits increased expression. Increased ADK activity causes intensified phosphorylation of adenosine to 5'-AMP, which therefore lowers the adenosine level in the extracellular spaces. These changes might initiate astrogliosis and epileptogenesis, which are the manifestations of epilepsy. Seizures might induce inflammatory processes and vice versa. Activation of P2X7 receptors causes intensified release of pro-inflammatory cytokines (IL-1β and TNF-α) and activates metabolic pathways that induce inflammatory processes in the CNS. Therefore, antagonists of P2X7 and the interleukin 1β receptor might be efficient drugs for recurring seizures and prolonged status epilepticus. Inhibitors of ADK would simultaneously inhibit the seizures, prevent the astrogliosis and epileptogenesis processes and prevent the formation of new epileptogenic foci. Therefore, these drugs might become beneficial seizure-suppressing drugs.

Astrocytic Acid-Sensing Ion Channel 1a Contributes to the Development of Chronic Epileptogenesis

Unraveling mechanisms underlying epileptogenesis after brain injury is an unmet medical challenge. Although histopathological studies have revealed that reactive astrogliosis and tissue acidosis are prominent features in epileptogenic foci, their roles in epileptogenesis remain unclear. Here, we explored whether astrocytic acid-sensing ion channel-1a (ASIC1a) contributes to the development of chronic epilepsy. High levels of ASIC1a were measured in reactive astrocytes in the hippocampi of patients with temporal lobe epilepsy (TLE) and epileptic mice. Extracellular acidosis caused a significant Ca²⁺ influx in cultured astrocytes, and this influx was sensitive to inhibition by the ASIC1a-specific blocker psalmotoxin 1 (PcTX1). In addition, recombinant adeno-associated virus (rAAV) vectors carrying a GFAP promoter in conjunction with ASIC1a shRNA or cDNA were generated to suppress or restore, respectively, ASIC1a expression in astrocytes. Injection of rAAV-ASIC1a-shRNA into the dentate gyrus of the wide type TLE mouse model resulted in the inhibition of astrocytic ASIC1a expression and a reduction in spontaneous seizures. By contrast, rAAV-ASIC1a-cDNA restored astrocytic ASIC1a expression in an ASIC1a knock-out TLE mouse model and increased the frequency of spontaneous seizures. Taken together, our results reveal that astrocytic ASIC1a may be an attractive new target for the treatment of epilepsy.

Leukocyte Infiltration Triggers Seizure Recurrence in a Rat Model of Temporal Lobe Epilepsy

Epilepsy, which affects about 1 % of the population worldwide, leads to poor prognosis and increased morbidity. However, effective drugs providing satisfactory control on seizure relapse were rare, which encouraged more etiological studies. Whether inflammation is one of key events underlying seizure is in debate. In order to explore the role of inflammatory in the pathogenesis and development of epilepsy, we conducted intra-caudal vein injection of leukocytes to aggravated brain inflammatory process in kainic acid-induced seizure model in this study. The results showed that intravenous administration of activated leukocytes increased the frequency and reduced the latent phase of seizure recurrences in rat models of epileptic seizure, during which leukocyte inflammation, brain-blood barrier damage, and neuron injury were also significantly aggravated, indicating that leukocyte infiltration might facilitate seizure recurrence through aggravating brain inflammation, brain-blood barrier damage, and neuron injury.

Effect of Liraglutide on Corneal Kindling Epilepsy Induced Depression and Cognitive Impairment in Mice

GLP-1 play important role in neuroprotection and GLP-1 receptor deficit mice showed decreased seizure threshold and increased cognitive impairment. Therefore, study was premeditated to investigate the effect of liraglutide (GLP-1 analogue) on cornel kindling epilepsy induced co-morbidities in mice. Corneal kindling was induced by electrical stimulation (6 mA, 50 Hz, 3 s); twice daily for 13 days. Liraglutide (75 and 150 µg/kg) and phenytoin (20 mg/kg) were administered in corneal kindled groups. On day 14, elevated plus maze, passive shock avoidance paradigms were performed, and on day 15, retention was taken. On day 16 tail suspension test were performed. On 20th day challenge test was performed with same electrical stimulation and retention was observed on elevated plus maze and passive avoidance paradigm. Animal were sacrificed on 21st day for biochemical (LPO, GSH, and nitrite) and neurochemical (GABA, glutamate, DA, NE, 5-HT and their metabolites) estimation. Electrical stimulation by corneal electrode for 13 days developed generalized clonic seizures, increased cognitive impairment, oxidative stress and neurochemical alteration in mice brain. Co-treatment with liraglutide (75 and 150 μg/kg) significantly prevented the seizure severity, restored behavioural activity, oxidative stress and restored the altered level of neurotransmitters observed in corneal kindled mouse.