Progress in neuroprotective strategies for preventing epilepsy

Hyperphosphorylated Tau in Mesial Temporal Lobe Epilepsy: a Neuropathological and Cognitive Study

Temporal lobe epilepsy (TLE) often courses with cognitive deficits, but its underlying neuronal basis remains unclear. Confluent data suggest that epilepsy share pathophysiological mechanisms with neurodegenerative diseases. However, as most studies analyze subjects 60 years old and older, it is challenging to rule out that neurodegenerative changes arise from age-related mechanisms rather than epilepsy in these individuals. To fill this gap, we conducted a neuropathological investigation of the hippocampal formation of 22 adults with mesial TLE and 20 age- and sex-matched controls (both younger than 60 years). Moreover, we interrogated the relationship between these neuropathological metrics and cognitive performance. Hippocampal formation extracted from patients with drug-resistant mesial TLE undergoing surgery and postmortem non-sclerotic hippocampal formation of clinically and neuropathologically controls underwent immunohistochemistry against amyloid β (Aβ), hyperphosphorylated tau (p-tau), and TAR DNA-binding protein-43 (TDP-43) proteins, followed by quantitative analysis. Patients underwent a comprehensive neuropsychological evaluation prior to surgery. TLE hippocampi showed a significantly higher burden of p-tau than controls, whereas Aβ deposits and abnormal inclusions of TDP-43 were absent in both groups. Patients with hippocampal sclerosis (HS) type 2 had higher immunostaining for p-tau than patients with HS type 1. In addition, p-tau burden was associated with impairment in attention tasks and seizures frequency. In this series of adults younger than 60 years-old, the increase of p-tau burden associated with higher frequency of seizures and attention impairment suggests the involvement of tau pathology as a potential contributor to cognitive deficits in mesial TLE.

Role of curcumin and its nanoformulations in the treatment of neurological diseases through the effects on stem cells

Curcumin from turmeric is a natural phenolic compound with a promising potential to regulate fundamental processes involved in neurological diseases, including inflammation, oxidative stress, protein aggregation, and apoptosis at the molecular level. In this regard, employing nanoformulation can improve curcumin efficiency by reducing its limitations, such as low bioavailability. Besides curcumin, growing data suggest that stem cells are a noteworthy candidate for neurodegenerative disorders therapy due to their anti-inflammatory, anti-oxidative, and neuronal-differentiation properties, which result in neuroprotection. Curcumin and stem cells have similar neurogenic features and can be co-administered in a cell-drug delivery system to achieve better combination therapeutic outcomes for neurological diseases. Based on the evidence, curcumin can induce the neuroprotective activity of stem cells by modulating their related signalling pathways. The present review is about the role of curcumin and its nanoformulations in the improvement of neurological diseases alone and through the effect on different categories of stem cells by discussing the underlying mechanisms to provide a roadmap for future investigations.

Intermittency properties in a temporal lobe epilepsy model

Neuronal synchronization is important for communication between brain regions and plays a key role in learning. However, changes in connectivity can lead to hyper-synchronized states related to epileptic seizures that occur intermittently with asynchronous states. The activity-regulated cytoskeleton-associated protein (ARC) is related to synaptic alterations which can lead to epilepsy. Induction of status epilepticus in rodent models causes the appearance of intense ARC immunoreactive neurons (IAINs), which present a higher number of connections and conductance intensity than non-IAINs. This alteration might contribute to abnormal epileptic seizure activity. In this work, we investigated how IAINs connectivity influences the firing pattern and synchronization in neural networks. Firstly, we showed the appearance of synchronized burst patterns due to the emergence of IAINs. Second, we described how the increase of IAINs connectivity favors the appearance of intermittent up and down activities associated with synchronous bursts and asynchronous spikes, respectively. Once the intermittent activity was properly characterized, we applied the optogenetics control of the high synchronous activities in the intermittent regime. To do this, we considered that 1% of neurons were transfected and became photosensitive. We observed that optogenetics methods to control synchronized burst patterns are effective when IAINs are chosen as photosensitive, but not effective in non-IAINs. Therefore, our analyses suggest that IAINs play a pivotal role in both the generation and suppression of highly synchronized activities.

Design and Characterization of Novel Small Molecule Activators of Excitatory Amino Acid Transporter 2

Excitotoxicity in the brain is a causal factor in several neurological and neurodegenerative disorders. Excitatory amino acid transporter 2 (EAAT2), an astrocytic glutamate transporter involved in the clearance of >80% of synaptic glutamate, is considered a therapeutically relevant target for excitotoxicity. We have previously designed GT951, an activator of EAAT2 with nanomolar efficacy but limited in vivo bioavailability. In this study, a pharmacophore-based screening and optimization resulted in the design of GTS467 and GTS511. GTS467 and GTS511 have low nanomolar efficacy in the glutamate uptake assay. Pharmacokinetic profiles (PK) of GTS511 show a >6 h half-life and higher bioavailability in plasma and the brain under all three routes of administration in rats. Similarly, GTS467 has high oral bioavailability (80-85%) in the brain and plasma with a >1 h half-life under all three dosing routes. These encouraging efficacy and PK profiles suggest that GTS511 and GTS467 can be further developed to treat neurological disorders caused by excitotoxicity.

Modified Xenopus laevis approach (R-FETAX) as an alternative test for the evaluation of foetal valproate spectrum disorder

In compliance to animal welfare 3Rs principle there is a great demand for refined tests alternative to classical mammal teratogenicity tests. We propose a refined alternative amphibian method (R-FETAX) to evaluate chemical induced embryotoxicity. The human foetal valproate spectrum disorder (FVSD) characteristics are morphological defects (including cranio-facial, neural tube defects) and behavioural alterations due to valproate (VPA) exposure in pregnancy. Vertebrate assays to evaluate FVSD include classical and alternative mammal (implying adult sacrifice), and non-mammal developmental models (zebrafish, amphibians, chick). Among these latter only zebrafish assays report in the same test both morphological and behavioural examinations. Compared to zebrafish, the amphibian Xenopus laevis excels having a more comparable organ development and morphology to mammalian systems. We used X. laevis embryos exposed during developmental specific windows to VPA therapeutic concentrations. Different VPA effects were observed depending on the exposure window: concentration-related embryo-lethal and teratogenic effects (neural tube, facial, tail defects) were observed in groups exposed at the organogenetic phylotypic stages. Neurobehavioral deficits were described using a functional swimming test at the highest VPA concentration exposure during the phylotypic stages and at any concentration during neurocognitive competent stages. Malformations were compared to those obtained in a mammalian assay (the rat post-implantation whole embryo culture method, WEC), that we used in the past to evaluate VPA teratogenicity. R-FETAX and WEC data were modelled and their relative sensitivity was calculated. We suggest the amphibian R-FETAX as a refined windowed alternative test for the evaluation of chemicals inducing both morphological and behavioural anomalies, including VPA.

Interweaving epilepsy and neurodegeneration: Vitamin E as a treatment approach

Epilepsy is the most common neurological disorder, affecting nearly 50 million people worldwide. The condition can be manifested either due to genetic predisposition or acquired from acute insult which leads to alteration of cellular and molecular mechanisms. Evaluating the latest and the current knowledge in regard to the mechanisms underlying molecular and cellular alteration, hyperexcitability is a consequence of an imbalanced state wherein enhance excitatory glutamatergic and reduced inhibitory GABAergic signaling is considered to be accountable for seizures associated damage. However, neurodegeneration contributing to epileptogenesis has become increasingly appreciated. The components at the helm of neurodegenerative alterations during epileptogenesis include GABAergic neuronal and receptor changes, neuroinflammation, alteration in axonal transport, oxidative stress, excitotoxicity, and other cellular as well as functional changes. Targeting neurodegeneration with vitamin E as an antioxidant, anti-inflammatory and neuroprotective may prove to be one of the therapeutic approaches useful in managing epilepsy. In this review, we discuss and converse about the seizure-induced episodes as a link for the development of neurodegenerative and pathological consequences of epilepsy. We also put forth a summary of the potential intervention with vitamin E therapy in the management of epilepsy.

Different Modes of Low-Frequency Focused Ultrasound-Mediated Attenuation of Epilepsy Based on the Topological Theory

Epilepsy is common brain dysfunction, where abnormal synchronized activities can be observed across multiple brain regions. Low-frequency focused pulsed ultrasound has been proven to modulate the epileptic brain network. In this study, we used two modes of low-intensity focused ultrasound (pulsed-wave and continuous-wave) to sonicate the brains of KA-induced epileptic rats, analyzed the EEG functional brain connections to explore their respective effect on the epileptic brain network, and discuss the mechanism of ultrasound neuromodulation. By comparing the brain network characteristics before and after sonication, we found that two modes of ultrasound both significantly affected the functional brain network, especially in the low-frequency band below 12 Hz. After two modes of sonication, the power spectral density of the EEG signals and the connection strength of the brain network were significantly reduced, but there was no significant difference between the two modes. Our results indicated that the ultrasound neuromodulation could effectively regulate the epileptic brain connections. The ultrasound-mediated attenuation of epilepsy was independent of modes of ultrasound.

Gene Therapy Repairs for the Epileptic Brain: Potential for Treatment and Future Directions

Epilepsy is a syndrome specified by frequent seizures and is one of the most prevalent neurological conditions, and that one-third of people of epilepsy are resistant to available drugs. Surgery is supposed to be the main treatment for the remedy of multiple drug-resistant epilepsy, but it is a drastic procedure. Advancement in genomic technologies indicates that gene therapy can make such surgery unnecessary. The considerable number of new studies show the significance of mutation in mammalian target of rapamycin pathway, NMDA receptors, GABA receptors, potassium channels and G-protein coupled receptors. Illustration of the meticulous drug in epilepsy targeting new expression of mutations in SCN8A, GRIN2A, GRIN2D and KCNT1 are conferred. Various methods are utilized to express a gene in a precise area of the brain; Transplantation of cells in an ex vivo approach (fetal cells, fibroblasts, immortalized cells), nonviral vector delivery and viral vector delivery like retrovirus, herpes simplex virus adenovirus and adeno-related virus. Gene therapy has thus been explored to generate anti-epileptogenic, anti-seizure and disease-modifying effects. Specific targeting of the epileptogenic region is facilitated by gene therapy, hence sparing the adjacent healthy tissue and decreasing the adverse effects that frequently go hand in hand with antiepileptic medication.

Pyrazolo[3,4-d]pyrimidine-based dual EGFR T790M/HER2 inhibitors: Design, synthesis, structure-activity relationship and biological activity as potential antitumor and anticonvulsant agents

A new series of pyrazolo[3,4-d]pyrimidine/triazine hybrids 6a-r was designed as antitumor and anticonvulsant agents. All the prepared compounds were evaluated against colon (HCT-116), breast (MCF-7) and normal human fibroblast (WI38) cell lines. The most potent derivatives against HCT-116 and MCF-7 cells were 6o and 6q, with IC₅₀ = 4.80 and 6.50 nM, respectively, when compared to lapatinib, the reference drug (IC₅₀ = 12.00 and 21.00 nM, on HCT-116 and MCF-7, sequentially). All other derivatives exhibited good to moderate cytotoxic activity. Four compounds 6f, 6j, 6o and 6q were evaluated for their EGFR T790M/HER2 inhibitory activity. They revealed 81.81-65.70% and 86.66-54.49% inhibitory activity against EGFR T790M and HER2 in a sequent. The most potent derivatives 6o and 6q were further estimated for cell cycle analysis showing pre G1 apoptotic activity and cell growth arrest at G2/M phase. Apoptotic marker proteins expression levels (caspase-3/7/9, Bax and Bcl-2) were measured for 6o and 6q. They showed pro-apoptotic effect by increasing caspase-3/7/9 protein levels and Bax/Bcl-2 ratio. Moreover, anticonvulsant activity for the prepared compounds 6a-r were evaluated in vivo using lithium-pilocarpine mice model of Status Epilepticus. EEG changes where recorded and MDA, GSH, GABA and glutamate were measured in brain tissue of different groups. All tested compounds revealed variable anti-epileptic effects, the most potent compounds were 6b and 6m. Also 6d, 6e, 6h, 6i, 6k, 6l and 6n compounds exhibited good anti-seizure activity, while compound 6j showed the lower activity. The rest of compounds displayed a neutral activity.

Early intervention with levetiracetam prevents the development of cortical hyperexcitability and spontaneous epileptiform activity in two models of neurotrauma in rats

This study examined the antiepileptogenic potential of the antiseizure drug (ASD) levetiracetam (LEV) using the in vitro traumatized-slice and in vivo controlled cortical impact (CCI) models of traumatic brain injury (TBI) in rats when administered early after the injury. For the in vitro model, acute coronal slices (400-450 μm) of rat neocortex (P21-32) were injured via a surgical cut that separated the superficial layers from the deeper regions. Persistent stimulus-evoked epileptiform activity developed within 1-2 h after trauma. In randomly selected slices, LEV (500 μM) was bath-applied for 1 h starting immediately or delayed by 30-80 min after injury. Treated and untreated slices were examined for epileptiform activity via intracellular and extracellular recordings. For the in vivo model, rats (P24-32) were subjected to a non-penetrating, focal, CCI injury targeting the neocortex (5.0 mm diameter; 2.0 mm depth). Immediately after injury, rats were given either a single dose of LEV (60-150 mg/kg, i.p.) or the saline vehicle. At 2-3 weeks after the injury, ex vivo cortical slices were examined for epileptiform activity. The results from the traumatized-slice experiments showed that in vitro treatment with LEV within 60 min of injury significantly reduced (> 50%) the proportion of slices that exhibited stimulus-evoked epileptiform activity. LEV treatment also increased the stimulus intensity required to trigger epileptiform bursts in injured slices by 2-4 fold. Consistent with these findings, LEV treatment of CCI-injured rats (n = 15) significantly reduced the proportion of animals that exhibited spontaneous and stimulus-evoked epileptiform bursts in ex vivo cortical slices compared to saline-treated controls (n = 15 rats), and also significantly increased the stimulus intensity required to evoke epileptiform bursts. These results suggest that early administration of LEV has the potential to prevent or reduce posttraumatic epileptogenesis and that there may be a narrow therapeutic window for successful prophylactic intervention.

Neuroprotective Effects of the Anti-cancer Drug Lapatinib Against Epileptic Seizures via Suppressing Glutathione Peroxidase 4-Dependent Ferroptosis

Epilepsy is a complex neurological disorder characterized by recurrent and unprovoked seizures. Neuronal death process is implicated in the development of repetitive epileptic seizures. Therefore, cell death can be harnessed for ceasing seizures and epileptogenesis. Oxidative stress is regarded as a contributing factor of neuronal death activation and there is compelling evidence supporting antioxidants hold promise in abrogating seizure-related cell modality. Lapatinib, a well-known anti-cancer drug, has been traditionally reported to exert anti-tumor effect via modulating oxidative stress and a recent work illustrates the improvement of encephalomyelitis in rodent models after lapatinib treatment. However, whether lapatinib is beneficial for inhibiting neuronal death and epileptic seizure remains unknown. Here, we found that lapatinib remarkably prevented kainic acid (KA)-epileptic seizures in mice and ferroptosis, a newly defined cell death which is associated with oxidative stress, was involved in the neuroprotection of lapatinib. In the ferroptotic cell death model, lapatinib exerted neuroprotection via restoring glutathione peroxidase 4 (GPX4). Treatment with GPX4 inhibitor ras-selective lethal small molecule 3 (RSL3) abrogated its anti-ferroptotic potential. In a mouse model of KA-triggered seizure, it was also validated that lapatinib blocked GPX4-dependent ferroptosis. It is concluded that lapatinib has neuroprotective potential against epileptic seizures via suppressing GPX4-mediated ferroptosis.

Involvement of the Benzodiazepine Site in the Anticonvulsant Activity of Tapinanthus globiferus against Pentylenetetrazole-induced Seizures in Mice

Tapinanthus globiferus is often referred to as an all-purpose herb for the treatment of stroke and epilepsy. The present study investigates the anticonvulsant effect of methanolic leaf extract, active fractions, and lupeol (isolate) of Tapinanthus globiferus in mice as well as the underlying mechanisms. Following phytochemical studies of T. globiferus, preliminary assays were performed to evaluate MLE-induced toxic effect and behavioral changes. The pentylenetetrazol (70 mg/kg, i. p.)-induced seizure was evaluated in mice that were pretreated orally with vehicle 10 mL/kg, MLE (4, 20, or 100 mg/kg), fractions (F1 to F6), lupeol 10 mg/kg or diazepam (3 mg/kg). Methanolic leaf extract preserved neuron viability as well as the relative organ weight, and hematological and biochemical parameters. The behavioral endpoints, neuromuscular coordination, and sensory response parameters revealed a dose-dependent effect of methanolic leaf extract. This extract, active fractions, lupeol, and diazepam potentiated the hypno-sedative effect of the barbiturate and attenuated PTZ-induced acute seizure. This antiseizure effect was completely reversed by flumazenil 2 mg/kg (benzodiazepine site antagonist). Altogether, the benzodiazepine site-mediated anticonvulsant effects of methanolic leaf extract, active fractions, and lupeol corroborate traditional application of T. globiferus against epilepsy.

Ketogenic diet, neuroprotection, and antiepileptogenesis

High fat, low carbohydrate ketogenic diets (KD) have been in use for the treatment of epilepsy for almost a hundred years. Remarkably, seizures that are resistant to conventional anti-seizure drugs can in many cases be controlled by the KD therapy, and it has been shown that many patients with epilepsy become seizure free even after discontinuation of the diet. These findings suggest that KD combine anti-seizure effects with disease modifying effects. In addition to the treatment of epilepsy, KDs are now widely used for the treatment of a wide range of conditions including weight reduction, diabetes, and cancer. The reason for the success of metabolic therapies is based on the synergism of at least a dozen different mechanisms through which KDs provide beneficial activities. Among the newest findings are epigenetic mechanisms (DNA methylation and histone acetylation) through which KD exerts long-lasting disease modifying effects. Here we review mechanisms through which KD can affect neuroprotection in the brain, and how a combination of those mechanisms with epigenetic alterations can attenuate and possibly reverse the development of epilepsy.

Revisiting the Impact of Neurodegenerative Proteins in Epilepsy: Focus on Alpha-Synuclein, Beta-Amyloid, and Tau

Lack of disease-modifying therapy against epileptogenesis reflects the complexity of the disease pathogenesis as well as the high demand to explore novel treatment strategies. In the pursuit of developing new therapeutic strategies against epileptogenesis, neurodegenerative proteins have recently gained increased attention. Owing to the fact that neurodegenerative disease and epileptogenesis possibly share a common underlying mechanism, targeting neurodegenerative proteins against epileptogenesis might represent a promising therapeutic approach. Herein, we review the association of neurodegenerative proteins, such as α-synuclein, amyloid-beta (Aβ), and tau protein, with epilepsy. Providing insight into the α-synuclein, Aβ and tau protein-mediated neurodegeneration mechanisms, and their implication in epileptogenesis will pave the way towards the development of new agents and treatment strategies.

Ryanodine receptors drive neuronal loss and regulate synaptic proteins during epileptogenesis

Status epilepticus (SE) is a clinical emergency that can lead to the development of temporal lobe epilepsy (TLE). The development and maintenance of spontaneous seizures in TLE are linked to calcium (Ca⁺²)-dependent processes such as neuronal cell loss and pathological synaptic plasticity. It has been shown that SE produces an increase in ryanodine receptor-dependent intracellular Ca⁺² levels in hippocampal neurons, which remain elevated during the progression of the disease. However, the participation of ryanodine receptors (RyRs) in the neuronal loss and circuitry rewiring that take place in the hippocampus after SE remains unknown. In this context, we first investigated the functional role of RyRs on the expression of synaptic and plasticity-related proteins during epileptogenesis induced by pilocarpine in Wistar rats. Intrahippocampal injection of dantrolene, a selective pharmacological blocker of RyRs, caused the increase of the presynaptic protein synapsin I (SYN) and synaptophysin (SYP) 48 h after SE induction. Specifically, we observed that SYN and SYP were regulated in hippocampal regions known to receive synaptic inputs, revealing that RyRs could be involved in network changes and/or neuronal protection after SE induction. In order to investigate whether the changes in SYN and SYP were related to neuroplastic changes that could contribute to pathological processes that occur after SE, we evaluated the levels of activity-regulated cytoskeleton-associated protein (ARC) and mossy fiber sprouting in the dentate gyrus (DG). Interestingly, we observed that although SE induced the appearance of intense ARC-positive cells, dantrolene treatment did not change the levels of ARC in both western blot and immunofluorescence analyses. Accordingly, in the same experimental conditions, we were not able to detect changes in the levels of both pre- and post-synaptic plasticity-related proteins, growth associated protein-43 (GAP-43) and postsynaptic density protein-95 (PSD-95), respectively. Additionally, the density of mossy fiber sprouting in the DG was not increased by dantrolene treatment. We next examined the effects of intrahippocampal injection of dantrolene on neurodegeneration. Notably, dantrolene promoted neuroprotective effects by decreasing neuronal cell loss in CA1 and CA3, which explains the increased levels of synaptic proteins, and the apparent lack of positive effect on pathological plasticity. Taken together, our results revealed that RyRs may have a major role in the hippocampal neurodegeneration associated to the development of acquired epilepsy.

The anticonvulsant effects of cannabidiol in experimental models of epileptic seizures: From behavior and mechanisms to clinical insights

Epilepsy is a neurological disorder characterized by the presence of seizures and neuropsychiatric comorbidities. Despite the number of antiepileptic drugs, one-third of patients did not have their seizures under control, leading to pharmacoresistance epilepsy. Cannabis sativa has been used since ancient times in Medicine for the treatment of many diseases, including convulsive seizures. In this context, Cannabidiol (CBD), a non-psychoactive phytocannabinoid present in Cannabis, has been a promising compound for treating epilepsies due to its anticonvulsant properties in animal models and humans, especially in pharmacoresistant patients. In this review, we summarize evidence of the CBD anticonvulsant activities present in a great diversity of animal models. Special attention was given to behavioral CBD effects and its translation to human epilepsies. CBD anticonvulsant effects are associated with a great variety of mechanisms of action such as endocannabinoid and calcium signaling. CBD has shown effectiveness in the clinical scenario for epilepsies, but its effects on epilepsy-related comorbidities are scarce even in basic research. More detailed and complex behavioral evaluation about CBD effects on seizures and epilepsy-related comorbidities are required.

Reactive oxygen species in status epilepticus

There has been growing evidence for a critical role of oxidative stress in neurodegenerative disease, providing novel targets for disease modifying treatments. Although antioxidants have been suggested and tried in the treatment of epilepsy, it is only recently that the pivotal role of oxidative stress in the pathophysiology of status epilepticus has been recognized. Although conventionally thought to be generated by mitochondria, reactive oxygen species during status epilepticus and prolonged seizure are generated mainly by NADPH (nicotinamide adenine dinucleotide phosphate) oxidase (stimulated by NMDA receptor activation). Excessive production of reactive oxygen species results in lipid peroxidation, DNA damage, enzyme inhibition, and mitochondrial damage, culminating in neuronal death. Antioxidant therapy has been hampered by poor CNS penetration and rapid consumption by oxidants. However, alternative approaches such as inhibiting NADPH oxidase or increasing endogenous antioxidant defenses through activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) could avoid these problems. Small molecules that increase Nrf2 activation have proven to be not only effective neuroprotectants following status epilepticus, but also potently antiepileptogenic. There are "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures".

Advances in the Potential Biomarkers of Epilepsy

Epilepsy is a group of chronic neurological disorders characterized by recurrent, spontaneous, and unpredictable seizures. It is one of the most common neurological disorders, affecting tens of millions of people worldwide. Comprehensive studies on epilepsy in recent decades have revealed the complexity of epileptogenesis, in which immunological processes, epigenetic modifications, and structural changes in neuronal tissues have been identified as playing a crucial role. This review discusses the recent advances in the biomarkers of epilepsy. We evaluate the possible molecular background underlying the clinical changes observed in recent studies, focusing on therapeutic investigations, and the evidence of their safety and efficacy in the human population. This article reviews the pathophysiology of epilepsy, including recent reports on the effects of oxidative stress and hypoxia, and focuses on specific biomarkers and their clinical implications, along with further perspectives in epilepsy research.

The Dentate Gyrus and Temporal Lobe Epilepsy: An "Exciting" Era

This review describes developments in epilepsy research during the last 3 to 4 decades that focused on the dentate gyrus (DG) and its role in temporal lobe epilepsy (TLE). The emphasis is on basic research in laboratory animals and is chronological, starting with hypotheses that attracted a lot of attention in the 1980s. Then experiments are described that addressed the questions, as well as new methods that often made the experiments possible. In addition, where new questions arose and the implications for clinical epilepsy are discussed.

Baicalein Exerts Neuroprotective Effects in FeCl3-Induced Posttraumatic Epileptic Seizures via Suppressing Ferroptosis

Posttraumatic epilepsy (PTE) is a prevalent type of acquired epilepsy secondary to traumatic brain injury, and is characterized by repeated seizures. Traditional antiepileptic drugs have minimal response in preventing posttraumatic epileptic seizures. It is essential for the development of new therapeutic strategy. Our previous work disclosed a potent neuroprotective role of baicalein, a flavonoid extracted from Scutellaria baicalensis Georgi, against inherited epilepsy in rats. Whether baicalein has protective potential in posttraumatic epileptic seizures and the possible molecular mechanism remain elusive. Additionally, the brain is vulnerable to lipid peroxidation-induced damage due to high consumption of oxygen and abundant polyunsaturated fatty acids in neuronal membranes. Our present investigation aimed to elucidate whether baicalein exerts neuroprotective effects on posttraumatic epileptic seizures by inhibiting ferroptosis, a newly discovered lipid peroxidation-dependent cell death modality. We found that baicalein significantly reduced seizure score, number of seizures, and average seizure duration in an iron chloride (FeCl₃)-induced PTE mouse model. The neuroprotective effect of baicalein was also validated in a ferric ammonium citrate (FAC)-induced HT22 hippocampal neuron damage model. Moreover, in vitro, baicalein could remarkably decrease ferroptotic indices (lipid reactive oxygen species, 4-hydroxynonenal, and prostaglandin endoperoxide synthase 2) and inhibit the expression of 12/15-lipoxygenase (12/15-LOX) in an iron-induced HT22 cell damage model. These findings were also validated in a mouse PTE model. It was concluded that baicalein exerted neuroprotective effects against posttraumatic epileptic seizures via suppressing ferroptosis and 12/15-LOX was likely to be involved in baicalein’s neuroprotection.

Mycophenolate mofetil contributes to downregulation of the hippocampal interleukin type 2 and 1β mediated PI3K/AKT/mTOR pathway hyperactivation and attenuates neurobehavioral comorbidities in a rat model of temporal lobe epilepsy

The role of neuroinflammatory mediators has been well established in the pathogenesis of temporal lobe epilepsy (TLE) and associated neurobehavioral comorbidities. Mycophenolate mofetil (MMF) is commonly used as an immunosuppressant in organ transplantations. Its neuroprotective effect is well explored in different preclinical and clinical studies. The present study was designed to investigate the effect of MMF in rat model of lithium pilocarpine (LiPc)-induced spontaneous recurrent seizures and its associated neurobehavioral comorbidities. MMF treatment showed a dose-dependent decrease in seizure severity and reduced aggression in epileptic rats. There was marked improvement in spatial and recognition memory functions, along with substantial decrease in depression-like behavior in MMF treated epileptic rats. There was considerable decrease in mossy fiber sprouting in the dentate gyrus and the cornu ammonis 3 regions of the hippocampus, along with reduction in neuronal death in the treated groups. Furthermore, the hippocampal mRNA level of IL-1β, IL-2, PI3K, AKT, HIF-1α, RAPTOR, mTOR, Rps6kb1 and Rps6 was found to be decreased in MMF treated animals. mTOR, S6, pS6 and GFAP protein expression was decreased, whereas NeuN was increased in the rat hippocampus of the treated animals. The results concluded that MMF suppress recurrent seizures, and improves its associated behavioral impairments and cognitive deficit in rat model of TLE. The observed effects of MMF be correlated with the inhibition of IL-2 and IL-1β linked PI3K/AKT/mTOR signaling pathway hyperactivation.

Parawixin2 Protects Hippocampal Cells in Experimental Temporal Lobe Epilepsy

Epilepsy is considered as one of the major disabling neuropathologies. Almost one third of adult patients with temporal lobe epilepsy (TLE) do not respond to current antiepileptic drugs (AEDs). Additionally, most AEDs do not have neuroprotective effects against the inherent neurodegenerative process underlying the hippocampal sclerosis on TLE. Dysfunctions in the GABAergic neurotransmission may contribute not only to the onset of epileptic activity but also constitute an important system for therapeutic approaches. Therefore, molecules that enhance GABA inhibitory effects could open novel avenues for the understanding of epileptic plasticity and for drug development. Parawixin2, a compound isolated from Parawixia bistriata spider venom, inhibits both GABA and glycine uptake and has an anticonvulsant effect against a wide range of chemoconvulsants. The neuroprotective potential of Parawixin2 was analyzed in a model of TLE induced by a long-lasting Status Epilepticus (SE), and its efficiency was compared to well-known neuroprotective drugs, such as riluzole and nipecotic acid. Neuroprotection was assessed through histological markers for cell density (Nissl), astrocytic reactivity (GFAP) and cell death labeling (TUNEL), which were performed 24 h and 72 h after SE. Parawixin2 treatment resulted in neuroprotective effects in a dose dependent manner at 24 h and 72 h after SE, as well as reduced reactive astrocytes and apoptotic cell death. Based on these findings, Parawixin2 has a great potential to be used as a tool for neuroscience research and as a probe to the development of novel GABAergic neuroprotective agents.

The Ethanol Fraction of White Rose Petal Extract Abrogates Excitotoxicity-Induced Neuronal Damage In Vivo and In Vitro through Inhibition of Oxidative Stress and Proinflammation

Since oxidative stress and inflammation are involved in seizure-related neurotoxicity, the neuroprotective effect of a white rose (Rosa hybrida) petal extract (WRPE) in mice that are challenged with kainic acid (KA) were examined using behavioral epileptiform seizures as well as biochemical and morphological parameters of oxidative stress and inflammation. WRPE (50–200 mg/kg) was orally administered to male ICR mice for 15 days, and intraperitoneally challenged with KA (30 mg/kg). Seizure activity, lipid peroxidation, inflammatory cytokines, and related enzymes were analyzed in the brain tissue, in addition to the morphological alterations in the hippocampal pyramidal neurons. Separately, antioxidant ingredients in WRPE were analyzed, and antioxidant, anti-inflammatory, and neuroprotective activities of WRPE were investigated in HB1.F3 human neural stem cells (NSCs) to elucidate underlying mechanisms. Total polyphenol and flavonoid contents in WRPE were 303.3 ± 15.3 mg gallic acid equivalent/g extract and 18.5 ± 2.2 mg catechin/g extract, respectively. WRPE exhibited strong radical-scavenging activities and inhibited lipid peroxidation in vitro, and protected glutamate-induced cytotoxicity in NSCs by suppressing inflammatory process. Treatment with WRPE attenuated epileptiform seizure scores to a half level in KA-challenged mice, and decreased hippocampal pyramidal neuronal injury and loss (cresyl violet and DAPI staining) as well as astrocyte activation (GFAP immunostaining). Lipid peroxidation was inhibited, and mRNA expression of antioxidant enzymes (GPx, PHGPx, SOD1, and SOD2) were recovered in the brain tissues. Inflammatory parameters (cytokines and enzymes) including NF-kB, IL-1β, TNF-α, IL-6, HMGB1, TGF-β, iNOS, COX2, and GFAP mRNAs and proteins were also down-regulated by WRPE treatment. Taken together, the results indicate that WRPE could attenuate KA-induced brain injury through antioxidative and anti-inflammatory activities.

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.

Targeting neurodegeneration to prevent post-traumatic epilepsy

In the quest for developing new therapeutic targets for post-traumatic epilepsies (PTE), identifying mechanisms relevant to development and progression of disease is critical. A growing body of literature suggests involvement of neurodegenerative mechanisms in the pathophysiology of acquired epilepsies, including following traumatic brain injury (TBI). In this review, we discuss the potential of some of these mechanisms to be targets for the development of a therapy against PTE.

A novel metabolism-based phenotypic drug discovery platform in zebrafish uncovers HDACs 1 and 3 as a potential combined anti-seizure drug target

Despite the development of newer anti-seizure medications over the past 50 years, 30-40% of patients with epilepsy remain refractory to treatment. One explanation for this lack of progress is that the current screening process is largely biased towards transmembrane channels and receptors, and ignores intracellular proteins and enzymes that might serve as efficacious molecular targets. Here, we report the development of a novel drug screening platform that harnesses the power of zebrafish genetics and combines it with in vivo bioenergetics screening assays to uncover therapeutic agents that improve mitochondrial health in diseased animals. By screening commercially available chemical libraries of approved drugs, for which the molecular targets and pathways are well characterized, we were able to reverse-identify the proteins targeted by efficacious compounds and confirm the physiological roles that they play by utilizing other pharmacological ligands. Indeed, using an 870-compound screen in kcna1-morpholino epileptic zebrafish larvae, we uncovered vorinostat (Zolinza™; suberanilohydroxamic acid, SAHA) as a potent anti-seizure agent. We further demonstrated that vorinostat decreased average daily seizures by ∼60% in epileptic Kcna1-null mice using video-EEG recordings. Given that vorinostat is a broad histone deacetylase (HDAC) inhibitor, we then delineated a specific subset of HDACs, namely HDACs 1 and 3, as potential drug targets for future screening. In summary, we have developed a novel phenotypic, metabolism-based experimental therapeutics platform that can be used to identify new molecular targets for future drug discovery in epilepsy.

Epilepsy-associated alterations in hippocampal excitability

The hippocampus exhibits a wide range of epilepsy-related abnormalities and is situated in the mesial temporal lobe, where limbic seizures begin. These abnormalities could affect membrane excitability and lead to overstimulation of neurons. Multiple overlapping processes refer to neural homeostatic responses develop in neurons that work together to restore neuronal firing rates to control levels. Nevertheless, homeostatic mechanisms are unable to restore normal neuronal excitability, and the epileptic hippocampus becomes hyperexcitable or hypoexcitable. Studies show that there is hyperexcitability even before starting recurrent spontaneous seizures, suggesting although hippocampal hyperexcitability may contribute to epileptogenesis, it alone is insufficient to produce epileptic seizures. This supports the concept that the hippocampus is not the only substrate for limbic seizure onset, and a broader hyperexcitable limbic structure may contribute to temporal lobe epilepsy (TLE) seizures. Nevertheless, seizures also occur in conditions where the hippocampus shows a hypoexcitable phenotype. Since TLE seizures most often originate in the hippocampus, it could therefore be assumed that both hippocampal hypoexcitability and hyperexcitability are undesirable states that make the epileptic hippocampal network less stable and may, under certain conditions, trigger seizures.

Accumulation of rest deficiency precedes sudden death of epileptic Kv1.1 knockout mice, a model of sudden unexpected death in epilepsy

OBJECTIVE

Chronic sleep deficiency is associated with early mortality. In the epileptic population, there is a higher prevalence of sleep disorders, and individuals with severe refractory epilepsy are at greater risk of premature mortality than the general population. Sudden unexpected death in epilepsy affects 1:1000 cases of epilepsy each year. Ketogenic diet (KD) treatment is one of the few effective options for refractory seizures. Despite KD reducing seizures and increasing longevity in Kv1.1 knockout (KO) mice, they still succumb to sudden death. This study aims to determine whether (1) the rest profiles of KO and KD-treated KO (KOKD) mice resemble each other as a function of either age or proximity to death and (2) the timing of death correlates with acute or chronic changes in rest.

METHODS

Noninvasive actimetry was used to monitor rest throughout the lives of KO and wild-type (WT) littermates administered standard diet or KD.

RESULTS

As KO mice age, rest is reduced (P < .0001). Rest is significantly improved in KDKO mice (P < .0001), resembling WT values at several ages. When age is removed as a variable and data are realigned to the day of death, the rest profiles of KO and KOKD groups worsen to similar degrees as a function of proximity to death. The amount of rest acutely is not sensitive to the timing of death, whereas chronic rest deficiency profiles (10-15 days prior to death) of both groups were indistinguishable. Chronic accumulation of rest deficiency over the final 15 days was associated with 75% of deaths.

SIGNIFICANCE

Our data suggest that the accumulated rest deficiency is associated with sudden death in Kv1.1 KO mice. These data (1) support the proposed clinical hypothesis that chronic sleep deficiency may be associated with early mortality in epileptic patients and (2) warrant future preclinical and clinical studies on sleep monitoring in epileptic patients.

Epigenetic interventions for epileptogenesis: A new frontier for curing epilepsy

This article highlights the emerging therapeutic potential of specific epigenetic modulators as promising antiepileptogenic or disease-modifying agents for curing epilepsy. Currently, there is an unmet need for antiepileptogenic agents that truly prevent the development of epilepsy in people at risk. There is strong evidence that epigenetic signaling, which exerts high fidelity regulation of gene expression, plays a crucial role in the pathophysiology of epileptogenesis and chronic epilepsy. These modifications are not hard-wired into the genome and are constantly reprogrammed by environmental influences. The potential epigenetic mechanisms, including histone modifications, DNA methylation, microRNA-based transcriptional control, and bromodomain reading activity, can drastically alter the neuronal gene expression profile by exerting their summative effects in a coordinated fashion. Such an epigenetic intervention appears more rational strategy for preventing epilepsy because it targets the primary pathway that initially triggers the numerous downstream cellular and molecular events mediating epileptogenesis. Among currently approved epigenetic drugs, the majority are anticancer drugs with well-established profiles in clinical trials and practice. Evidence from preclinical studies supports the premise that these drugs may be applied to a wide range of brain disorders. Targeting histone deacetylation by inhibiting histone deacetylase enzymes appears to be one promising epigenetic therapy since certain inhibitors have been shown to prevent epileptogenesis in animal models. However, developing neuronal specific epigenetic modulators requires rational, pathophysiology-based optimization to efficiently intercept the upstream pathways in epileptogenesis. Overall, epigenetic agents have been well positioned as new frontier tools towards the national goal of curing epilepsy.

Treatment of refractory epilepsy patients with autologous mesenchymal stem cells reduces seizure frequency: An open label study

PURPOSE

Existing anti-epileptic drugs (AED) have limited efficiency in many patients, necessitating the search for alternative approaches such as stem cell therapy. We report the use of autologous patient-derived mesenchymal stem cells (MSC) as a therapeutic agent in symptomatic drug-resistant epilepsy in a Phase I open label clinical trial (registered as NCT02497443).

PATIENTS AND METHODS

The patients received either standard treatment with AED (control group), or AED supplemented with single intravenous administration of undifferentiated autologous MSC (target dose of 1×10⁶cells/kg), followed by a single intrathecal injection of neurally induced autologous MSC (target dose of 0.1×10⁶cells/kg).

RESULTS

MSC injections were well tolerated and did not cause any severe adverse effects. Seizure frequency was designated as the main outcome and evaluated at 1 year time point. 3 out of 10 patients in MSC therapy group achieved remission (no seizures for one year and more), and 5 additional patients became responders to AEDs, while only 2 out of 12 patients became responders in control group (difference significant, P=0.0135).

CONCLUSIONS

MSC possess unique immunomodulatory properties and are a safe and promising candidate for cell therapy in AED resistant epilepsy patients.

Neuroprotective Actions of Dietary Choline

Choline is an essential nutrient for humans. It is a precursor of membrane phospholipids (e.g., phosphatidylcholine (PC)), the neurotransmitter acetylcholine, and via betaine, the methyl group donor S-adenosylmethionine. High choline intake during gestation and early postnatal development in rat and mouse models improves cognitive function in adulthood, prevents age-related memory decline, and protects the brain from the neuropathological changes associated with Alzheimer’s disease (AD), and neurological damage associated with epilepsy, fetal alcohol syndrome, and inherited conditions such as Down and Rett syndromes. These effects of choline are correlated with modifications in histone and DNA methylation in brain, and with alterations in the expression of genes that encode proteins important for learning and memory processing, suggesting a possible epigenomic mechanism of action. Dietary choline intake in the adult may also influence cognitive function via an effect on PC containing eicosapentaenoic and docosahexaenoic acids; polyunsaturated species of PC whose levels are reduced in brains from AD patients, and is associated with higher memory performance, and resistance to cognitive decline.

Effect of lamotrigine on seizure development in a rat pentylenetetrazole kindling model

INTRODUCTION

Epileptogenesis is a process of seizure development. Lamotrigine is a novel antiepileptic drug which is also used for antiepileptogenic research. Kindling models are recommended as potentially useful tools for antiepileptogenic treatment discovery. However, previous studies demonstrated that the antiepileptogenic effect of lamotrigine is controversial in the electrical kindling model. Chemical kindling such as with pentylenetetrazole is another kindling model. The aims of this study were to examine whether lamotrigine could prevent the development of seizure in pentylenetetrazole kindling rats.

METHODS

Female rats were kindled by subconvulsive doses of pentylenetetrazole (35 mg/kg) once every other day for 15 times. Thereafter, the kindled rats received different doses of lamotrigine (5, 10 and 20 mg/kg) before pentylenetetrazole to observe the anticonvulsant effect. For the antiepileptogenic experiment, rats were kindled as the same way while pretreated (1 h) with different doses of lamotrigine (5, 10 and 20 mg/kg) before each injection of pentylenetetrazole. After a washout period for 1 week, the rats were administrated with pentylenetetrazole again for 3 times. The seizures were recorded each time. Later it was in vivo electrophysiological experiments followed with histologic analysis.

RESULTS

For the anticonvulsant experiment lamotrigine dose-dependently suppressed pentylenetetrazole-induced seizures. Here, 20 mg/kg of lamotrigine pretreatment significantly blocked the seizure development in rats for their seizure stages remained longer in 1-3 during the kindling phase. Mean seizure stages or generalized seizure durations in the 10 and 20 mg/kg lamotrigine pretreated groups were significantly lower or shorter when received 3 times of pentylenetetrazole after the washout period. Electrophysiological study also demonstrated 20 mg/kg of lamotrigine pretreatment obviously eliminated increased population spike amplitude in hippocampus. However, different doses of lamotrigine pretreatment could not alleviate severity of hippocampal neuronal damage.

CONCLUSIONS

The results suggest that adequate doses of lamotrigine can prevent seizure development in the pentylenetetrazole kindling rat model.

Novel therapeutic approaches for disease-modification of epileptogenesis for curing epilepsy

This article describes the recent advances in epileptogenesis and novel therapeutic approaches for the prevention of epilepsy, with a special emphasis on the pharmacological basis of disease-modification of epileptogenesis for curing epilepsy. Here we assess animal studies and human clinical trials of epilepsy spanning 1982-2016. Epilepsy arises from a number of neuronal factors that trigger epileptogenesis, which is the process by which a brain shifts from a normal physiologic state to an epileptic condition. The events precipitating these changes can be of diverse origin, including traumatic brain injury, cerebrovascular damage, infections, chemical neurotoxicity, and emergency seizure conditions such as status epilepticus. Expectedly, the molecular and system mechanisms responsible for epileptogenesis are not well defined or understood. To date, there is no approved therapy for the prevention of epilepsy. Epigenetic dysregulation, neuroinflammation, and neurodegeneration appear to trigger epileptogenesis. Targeted drugs are being identified that can truly prevent the development of epilepsy in at-risk people. The promising agents include rapamycin, COX-2 inhibitors, TRK inhibitors, epigenetic modulators, JAK-STAT inhibitors, and neurosteroids. Recent evidence suggests that neurosteroids may play a role in modulating epileptogenesis. A number of promising drugs are under investigation for the prevention or modification of epileptogenesis to halt the development of epilepsy. Some drugs in development appear rational for preventing epilepsy because they target the initial trigger or related signaling pathways as the brain becomes progressively more prone to seizures. Additional research into the target validity and clinical investigation is essential to make new frontiers in curing epilepsy.

The beneficial effects of l-cysteine on brain antioxidants of rats affected by sodium valproate

Oxidative stress caused by sodium valproate (SV) is known to play a key role in the pathogenesis of brain tissue. The present study was designed to evaluate the protective effect of l-cysteine (LC) on the antioxidants of brain tissue of rats. The animals were divided into six groups: control group 1 was treated with saline as vehicle, groups 2 and 3 were treated with low and high doses of SV (100 and 500 mg/kg, respectively), group 4 was treated with LC (100 mg/kg), and groups 5 and 6 were treated with low-dose SV + LC and high-dose SV + LC, respectively. All the groups were treated orally by gastric tube for 30 successive days. Some antioxidant parameters were determined. Brain tissue (cerebral cortex) of SV-treated animals showed an increase in lipid peroxidation (LPO) and reduction in activity of enzymatic antioxidant and total antioxidant levels. Histopathological examination of cerebral cortex of SV rats showed astrocytic swelling, inflammation, and necrosis. After 4 weeks of the combination treatment of SV and LC daily, results showed significant improvement in the activity of cathepsin marker enzymes and restored the structure of the brain. LC was able to ameliorate oxidative stress deficits observed in SV rats. LC decreased LPO level and was also able to restore the activity of antioxidant enzymes as well as structural deficits observed in the brain of SV animals. The protective effect of LC in SV-treated rats is mediated through attenuation of oxidative stress, suggesting a therapeutic role for LC in individuals treated with SV.

Inflammatory aspects of epileptogenesis: contribution of molecular inflammatory mechanisms

OBJECTIVE

Epilepsy is a chronic neurological disease characterised with seizures. The aetiology of the most generalised epilepsies cannot be explicitly determined and the seizures are pronounced to be genetically determined by disturbances of receptors in central nervous system. Besides, neurotransmitter distributions or other metabolic problems are supposed to involve in epileptogenesis. Lack of adequate data about pharmacological agents that have antiepileptogenic effects point to need of research on this field. Thus, in this review, inflammatory aspects of epileptogenesis has been focussed via considering several concepts like role of immune system, blood-brain barrier and antibody involvement in epileptogenesis.

METHODS

We conducted an evidence-based review of the literatures in order to evaluate the possible participation of inflammatory processes to epileptogenesis and also, promising agents which are effective to these processes. We searched PubMed database up to November 2015 with no date restrictions.

RESULTS

In the present review, 163 appropriate articles were included. Obtained data suggests that inflammatory processes participate to epileptogenesis in several ways like affecting fibroblast growth factor-2 and tropomyosin receptor kinase B signalling pathways, detrimental proinflammatory pathways [such as the interleukin-1 beta (IL-1β)-interleukin-1 receptor type 1 (IL-1R1) system], mammalian target of rapamycin pathway, microglial activities, release of glial inflammatory proteins (such as macrophage inflammatory protein, interleukin 6, C-C motif ligand 2 and IL-1β), adhesion molecules that are suggested to function in signalling pathways between neurons and microglia and also linkage between these molecules and proinflammatory cytokines.

CONCLUSION

The literature research indicated that inflammation is a part of epileptogenesis. For this reason, further studies are necessary for assessing agents that will be effective in clinical use for therapeutic treatment of epileptogenesis.

Anticonvulsant effect of argan oil on pilocarpine model induced status epilepticus in wistar rats

Argan oil (AO) is rich in oleic and linoleic acids, polyphenols, sterols, and tocopherols. This composition gives it numerous beneficial pharmacological effects such as hypolipemiant, hypotensive, and antiproliferative. Oxidative stress is a mechanism of cell death induced by seizures and status epilepticus (SE). This study aims at investigating AO effects on (i) latency to first seizure, seizure severity, weight loss, mortality rate, (ii) lipid peroxidation level, nitrite level, and catalase activity in the hippocampus after SE induced by pilocarpine (PC). Wistar rats (1-month old) were daily administered by oral gavage with AO (1 ml/100 g/day) or with NaCl 0.9% during 2 months before receiving PC (400 mg/kg). After the PC injection, all groups were observed for 24 h. The catalase activity, the lipid peroxidation, and nitrite concentrations were measured using spectrophotometric methods. AO pretreatment increased the latency to first seizures, decreased the weight loss, and reduced mortality rate after SE. AO pretreatment produces significant decrease of the lipid peroxidation and nitrite levels. On the contrary, AO increased the catalase activity in rat hippocampus after seizures. For the first time, our results suggest that AO pretreatment is capable of attenuating seizure severity and oxidative stress in the hippocampus of Wistar rats. This indicates that AO may exhibit a neuroprotection against the temporal lobe epilepsy. Further investigations are in progress to confirm this pharmacological property.

Xenograft of human umbilical mesenchymal stem cells from Wharton's jelly as a potential therapy for rat pilocarpine-induced epilepsy

We evaluated the effects of intra-hippocampal transplantation of human umbilical mesenchymal stem cells (HUMSCs) on pilocarpine-treated rats. Sprague-Dawley rats were divided into the following three groups: (1) a normal group of rats receiving only PBS, (2) a status epilepticus (SE) group of rats with pilocarpine-induced SE and PBS injected into the hippocampi, and (3) a SE+HUMSC group of SE rats with HUMSC transplantation. Spontaneous recurrent motor seizures (SRMS) were monitored using simultaneous video and electroencephalographic recordings at two to four weeks after SE induction. The results showed that the number of SRMS within two to four weeks after SE was significantly decreased in SE+HUMSCs rats compared with SE rats. All of the rats were sacrificed on Day 29 after SE. Hippocampal morphology and volume were evaluated using Nissl staining and magnetic resonance imaging. The results showed that the volume of the dorsal hippocampus was smaller in SE rats compared with normal and SE+HUMSCs rats. The pyramidal neuron loss in CA1 and CA3 regions was more severe in the SE rats than in normal and SE+HUMSCs rats. No significant differences were found in the hippocampal neuronal loss or in the number of dentate GABAergic neurons between normal and SE+HUMSCs rats. Compared with the SE rats, the SE+HUMSCs rats exhibited a suppression of astrocyte activity and aberrant mossy fiber sprouting. Implanted HUMSCs survived in the hippocampus and released cytokines, including FGF-6, amphiregulin, glucocorticoid-induced tumor necrosis factors receptor (GITR), MIP-3β, and osteoprotegerin. In an in vitro study, exposure of cortical neurons to glutamate showed a significant decrease in cell viability, which was preventable by co-culturing with HUMSCs. Above all, the expression of human osteoprotegerin and amphiregulin were significantly increased in the media of the co-culture of neurons and HUMSCs. Our results demonstrate the therapeutic benefits of HUMSC transplantation for the development of epilepsy, which are likely due to the ability of the cells to produce neuroprotective and anti-inflammatory cytokines. Thus, HUMSC transplantation may be an effective therapy in the future.

Effect of endurance training on seizure susceptibility, behavioral changes and neuronal damage after kainate-induced status epilepticus in spontaneously hypertensive rats

The therapeutic efficacy of regular physical exercises in an animal model of epilepsy and depression comorbidity has been confirmed previously. In the present study, we examined the effects of endurance training on susceptibility to kainate (KA)-induced status epilepticus (SE), behavioral changes and neuronal damage in spontaneously hypertensive rats (SHRs). Male SHRs were randomly divided into two groups. One group was exercised on a treadmill with submaximal loading for four weeks and the other group was sedentary. Immediately after the training period, SE was evoked in half of the sedentary and trained rats by KA, while the other half of the two groups received saline. Basal systolic (SP), diastolic (DP) and mean arterial pressure (MAP) of all rats were measured at the beginning and at the end of the training period. Anxiety, memory and depression-like behaviour were evaluated a month after SE. The release of 5-HT in the hippocampus was measured using a liquid scintillation method and neuronal damage was analyzed by hematoxylin and eosin staining. SP and MAP of exercised SHRs decreased in comparison with the initial values. The increased resistance of SHRs to KA-induced SE was accompanied by an elongated latent seizure-free period, improved object recognition memory and antidepressant effect after the training program. While the anticonvulsant and positive behavioral effects of endurance training were accompanied by an increase of 5-HT release in the hippocampus, it did not exert neuroprotective activity. Our results indicate that prior exercise is an effective means to attenuate KA-induced seizures and comorbid behavioral changes in a model of hypertension and epilepsy suggesting a potential influence of hippocampal 5-HT on a comorbid depression. However, this beneficial impact does not prevent the development of epilepsy and concomitant brain damage.

Thyroid hormones: Possible roles in epilepsy pathology

Thyroid hormones (THs) L-thyroxine and L-triiodothyronine, primarily known as metabolism regulators, are tyrosine-derived hormones produced by the thyroid gland. They play an essential role in normal central nervous system development and physiological function. By binding to nuclear receptors and modulating gene expression, THs influence neuronal migration, differentiation, myelination, synaptogenesis and neurogenesis in developing and adult brains. Any uncorrected THs supply deficiency in early life may result in irreversible neurological and motor deficits. The development and function of GABAergic neurons as well as glutamatergic transmission are also affected by THs. Though the underlying molecular mechanisms still remain unknown, the effects of THs on inhibitory and excitatory neurons may affect brain seizure activity. The enduring predisposition of the brain to generate epileptic seizures leads to a complex chronic brain disorder known as epilepsy. Pathologically, epilepsy may be accompanied by mitochondrial dysfunction, oxidative stress and eventually dysregulation of excitatory glutamatergic and inhibitory GABAergic neurotransmission. Based on the latest evidence on the association between THs and epilepsy, we hypothesize that THs abnormalities may contribute to the pathogenesis of epilepsy. We also review gender differences and the presumed underlying mechanisms through which TH abnormalities may affect epilepsy here.

Ultrasound stimulation inhibits recurrent seizures and improves behavioral outcome in an experimental model of mesial temporal lobe epilepsy

Current therapies for epilepsy consist mostly of pharmacological agents or invasive surgery. Recently, ultrasound (US) stimulation has been considered a promising tool for the noninvasive treatment of brain diseases, including epilepsy. However, in temporal lobe epilepsy (TLE), a common form of epilepsy, neurophysiological and functional outcomes following US stimulation are not well defined. To address this, we developed a paradigm of transcranial pulsed US stimulation to efficiently suppress seizure activity in the initial/acute period in a kainate (KA)-induced mouse model of mesial TLE. Pulsed US stimulation inhibited acute seizure activity and either delayed the onset of or suppressed status epilepticus (SE). Kainate-treated mice that had received US stimulation in the initial period exhibited fewer spontaneous recurrent seizures (SRSs) and improved performance in behavioral tasks assessing sociability and depression in the chronic period of epilepsy. Our results demonstrate that US stimulation in the acute period of epilepsy can inhibit SRSs and improve behavioral outcomes in a mouse model of mesial TLE. The present study suggests that noninvasive transcranial pulsed US stimulation may be feasible as an adjuvant therapy in patients with epilepsy. This article is part of a Special Issue entitled "Status Epilepticus".

Regenerative therapy for hippocampal degenerative diseases: lessons from preclinical studies

Increase in life expectancy has put neurodegenerative diseases on the rise. Amongst these, degenerative diseases involving hippocampus like Alzheimer's disease (AD) and temporal lobe epilepsy (TLE) are ranked higher as it is vulnerable to excitotoxicity induced neuronal dysfunction and death resulting in cognitive impairment. Modern medicines have not succeeded in halting the progression of these diseases rendering them incurable and often fatal. Under such scenario, regenerative studies employing stem cells or their by-products in animal models of AD and TLE have yielded encourageing results. This review focuses on the distinct cell types, such as hippocampal cell lines, neural precursor cells, embryonic stem cells derived neural precursor cells, induced pluripotent stem cells, induced neurons and mesenchymal stem cells, which can be employed to rescue hippocampal functions in neurodegenerative diseases like AD and TLE. Besides, the divergent mechanisms through which cell based therapy confer neuroprotection, current impediments and possible improvements in stem cell transplantation strategies are discussed. Authors are aware of the voluminous literature available on this issue and have made a sincere attempt to put forth the current status of research in the field of cell based therapy concurrently discussing the promise it holds for combating neurodegenerative diseases like AD and TLE in the near future. Copyright © 2015 John Wiley & Sons, Ltd.

Decursin attenuates kainic acid-induced seizures in mice

Epilepsy is a neurological disorder with recurrent unprovoked seizures as the main symptom. Of the coumarin derivatives in Angelica gigas, decursin, a major coumarin component, was reported to exhibit significant protective activity against glutamate-induced neurotoxicity when added to primary cultures of rat cortical cells. This study served to investigate the effects of decursin on a kainic acid (KA)-induced status epilepticus model. Thirty minutes after intraperitoneal injections of decursin (20 mg/kg) in male 7-week-old C57BL/6 mice, the animals were treated with KA (30 mg/kg, intraperitoneally) and then examined for behavioral seizure score, electroencephalogram, seizure-related expressed protein levels, neuronal cell loss, neurodegeneration, and astrogliosis. KA injections significantly enhanced neurodegenerative conditions but treatment with decursin 30 min before KA injection reduced the detrimental effects of KA in mice. The decursin-treated KA-injected group showed significantly decreased behavioral seizure activity and remarkably attenuated intense and high-frequency seizure discharges in the parietal cortex for 2 h compared with the group treated only with KA. Furthermore, in-vivo results indicated that decursin strongly inhibits selective neuronal death, astrogliosis, and oxidative stress induced by KA administration. Therefore decursin is able to attenuate KA-induced seizures and could have potential as an antiepileptic drug.

Prospects of epileptogenesis prevention

Epilepsy is a common neurologic disease, affecting about 1-2% of the population. In around 30% of patients with epilepsy, their seizures are not satisfactorily controlled and drug-resistant epilepsy constitutes a real therapeutic challenge. Consequently, there are efforts aimed at the inhibition of epileptogenesis, a process of converting a normal into an epileptic brain. Data on this problem have been mainly obtained in post-status epilepticus rodent models in which spontaneous seizure activity and behavioral disturbances develop over time. Among antiepileptic drugs, diazepam at high dose of 20mg/kg given during status epilepticus, significantly inhibited the development of spontaneous seizures and also, a strong neuroprotective effect was evident. Also gabapentin and valproate (over a period of 40 days) proved effective in the inhibition of spontaneous seizure activity and reduction of behavioral deficit. However, there are also data that valproate (over 28 days) significantly improved the behavioral performance without affecting the occurrence of spontaneous seizures. A number of antiepileptic drugs, carbamazepine, lamotrigine, levetiracetam, phenobarbital, and topiramate were completely ineffective. Among non-antiepileptic drugs, some promise show rapamycin, losartan and combinations of anti-inflammatory drugs, targeting different inflammatory pathways. Inhibition of epileptogenesis may become a valuable therapeutic approach provided that there are reliable markers of this process. Actually, such markers begin to emerge.