Ionotropic Glutamate Receptors in Epilepsy: A Review Focusing on AMPA and NMDA Receptors

Novel insight into astrocyte-mediated gliotransmission modulates the synaptic plasticity in major depressive disorder

Major depressive disorder (MDD) is a form of glial cell-based synaptic dysfunction disease in which glial cells interact closely with neuronal synapses and perform synaptic information processing. Glial cells, particularly astrocytes, are active components of the brain and are responsible for synaptic activity through the release gliotransmitters. A reduced density of astrocytes and astrocyte dysfunction have both been identified the brains of patients with MDD. Furthermore, gliotransmission, i.e., active information transfer mediated by gliotransmitters between astrocytes and neurons, is thought to be involved in the pathogenesis of MDD. However, the mechanism by which astrocyte-mediated gliotransmission contributes to depression remains unknown. This review therefore summarizes the alterations in astrocytes in MDD, including astrocyte marker, connexin 43 (Cx43) expression, Cx43 gap junctions, and Cx43 hemichannels, and describes the regulatory mechanisms of astrocytes involved in synaptic plasticity. Additionally, we investigate the mechanisms acting of the glutamatergic, gamma-aminobutyric acidergic, and purinergic systems that modulate synaptic function and the antidepressant mechanisms of the related receptor antagonists. Further, we summarize the roles of glutamate, gamma-aminobutyric acid, d-serine, and adenosine triphosphate in depression, providing a basis for the identification of diagnostic and therapeutic targets for MDD.

Presynaptic antiseizure medications - basic mechanisms and clues for their rational combinations

Among clinically highly efficient antiseizure medications (ASMs) there are modifiers of the presynaptic release machinery. Of them, levetiracetam and brivaracetam show a high affinity to the synaptic vesicle protein type 2 A (SV2A), whereas pregabalin and gabapentin are selective ligands for the α2δ1 subunits of the voltage-gated calcium channels. In this paper, we present recent progress in understanding the significance of presynaptic release machinery in the neurochemical mechanisms of epilepsy and ASMs. Furthermore, we discuss whether the knowledge of the basic mechanisms of the presynaptically acting ASMs might help establish a rational polytherapy for drug-resistant epilepsy.

"Sigma-1 receptor modulation by clemastine highlights its repurposing as neuroprotective agent against seizures and cognitive deficits in PTZ-kindled rats"

Epilepsy is a neurological disorder characterized by recurrent spontaneous seizures alongside other neurological comorbidities. Cognitive impairment is the most frequent comorbidity secondary to progressive neurologic changes in epilepsy. Sigma 1 receptors (σ1 receptors) are involved in the neuroprotection and pathophysiology of both conditions and targeting these receptors may have the potential to modulate both seizures and comorbidities. The current research demonstrated the effect of clemastine (10 mg/kg, P.O.), a non-selective σ1 receptor agonist, on pentylenetetrazol (PTZ) (35 mg/kg, i.p., every 48 h for 14 doses)-kindling rats by acting on σ1 receptors through its anti-inflammatory/antioxidant capacity. Clemastine and phenytoin (30 mg/kg, P.O.) or their combination were given once daily. Clemastine treatment showed a significant effect on neurochemical, behavioural, and histopathological analyses through modulation of σ1 receptors. It protected the kindling animals from seizures and attenuated their cognitive impairment in the Morris water maze test by reversing the PTZ hippocampal neuroinflammation/oxidative stress state through a significant increase in inositol-requiring enzyme 1 (IRE1), x-box binding protein 1 (XBP1), along with a reduction of total reactive oxygen species (TROS) and amyloid beta protein (Aβ). The involvement of σ1 receptors in the protective effects of clemastine was confirmed by their abrogation when utilizing NE-100, a selective σ1 receptor antagonist. In light of our findings, modulating σ1 receptors emerges as a compelling therapeutic strategy for epilepsy and its associated cognitive impairments. The significant neuroprotective effects observed with clemastine underscore the potential of σ1 receptor-targeted treatments to address both the primary symptoms and comorbidities of neurological disorders.

Recording of hippocampal activity on the effect of convulsant doses of caffeine

Seizures occur when there is a hyper-excitation of the outer layer of the brain, with subsequent excessive synchrony in a group of neurons. According to the World Health Organization (WHO), an estimated 50 million people are affected by this disease, a third of whom are resistant to the treatments available on the market. Caffeine (1,3,7-trimethylxanthine), which belongs to the purine alkaloid family, is the most widely consumed psychoactive drug in the world. It is ingested by people through drinks containing this substance, such as coffee, and as an adjuvant in analgesic therapy with non-steroidal antiflammatory drugs. The present study evaluated the electrocorticographic changes observed in the hippocampus of Wistar rats subjected to acute doses of caffeine (150 mg/kg i.p), which represents a toxic dose of caffeine corresponding to an estimated acute intake of more than 12 cups of coffee to record its convulsant activity. Our results showed, for the first time, that the administration of high doses of caffeine (150 mg/kg i.p.) in rats caused an increase in the spectral distribution of power in all frequency bands and suggested the appearance of periods of ictal and interictal peaks in the electrocorticogram (ECog). We have also shown that the anticonvulsants phenytoin, diazepam and phenobarbital have a satisfactory response when associated with caffeine.

APP fragment controls both ionotropic and non-ionotropic signaling of NMDA receptors

NMDA receptors (NMDARs) are ionotropic receptors crucial for brain information processing. Yet, evidence also supports an ion-flux-independent signaling mode mediating synaptic long-term depression (LTD) and spine shrinkage. Here, we identify AETA (Aη), an amyloid-β precursor protein (APP) cleavage product, as an NMDAR modulator with the unique dual regulatory capacity to impact both signaling modes. AETA inhibits ionotropic NMDAR activity by competing with the co-agonist and induces an intracellular conformational modification of GluN1 subunits. This favors non-ionotropic NMDAR signaling leading to enhanced LTD and favors spine shrinkage. Endogenously, AETA production is increased by in vivo chemogenetically induced neuronal activity. Genetic deletion of AETA production alters NMDAR transmission and prevents LTD, phenotypes rescued by acute exogenous AETA application. This genetic deletion also impairs contextual fear memory. Our findings demonstrate AETA-dependent NMDAR activation (ADNA), characterizing AETA as a unique type of endogenous NMDAR modulator that exerts bidirectional control over NMDAR signaling and associated information processing.

Prophylactic treatment with the c-Abl inhibitor, neurotinib, diminishes neuronal damage and the convulsive state in pilocarpine-induced mice

The molecular mechanisms underlying seizure generation remain elusive, yet they are crucial for developing effective treatments for epilepsy. The current study shows that inhibiting c-Abl tyrosine kinase prevents apoptosis, reduces dendritic spine loss, and maintains N-methyl-d-aspartate (NMDA) receptor subunit 2B (NR2B) phosphorylated in in vitro models of excitotoxicity. Pilocarpine-induced status epilepticus (SE) in mice promotes c-Abl phosphorylation, and disrupting c-Abl activity leads to fewer seizures, increases latency toward SE, and improved animal survival. Currently, clinically used c-Abl inhibitors are non-selective and have poor brain penetration. The allosteric c-Abl inhibitor, neurotinib, used here has favorable potency, selectivity, pharmacokinetics, and vastly improved brain penetration. Neurotinib-administered mice have fewer seizures and improved survival following pilocarpine-SE induction. Our findings reveal c-Abl kinase activation as a key factor in ictogenesis and highlight the impact of its inhibition in preventing the insurgence of epileptic-like seizures in rodents and humans.

The Use of Compounds Derived from Cannabis sativa in the Treatment of Epilepsy, Painful Conditions, and Neuropsychiatric and Neurodegenerative Disorders

Neurological disorders present a wide range of symptoms and challenges in diagnosis and treatment. Cannabis sativa, with its diverse chemical composition, offers potential therapeutic benefits due to its anticonvulsive, analgesic, anti-inflammatory, and neuroprotective properties. Beyond cannabinoids, cannabis contains terpenes and polyphenols, which synergistically enhance its pharmacological effects. Various administration routes, including vaporization, oral ingestion, sublingual, and rectal, provide flexibility in treatment delivery. This review shows the therapeutic efficacy of cannabis in managing neurological disorders such as epilepsy, neurodegenerative diseases, neurodevelopmental disorders, psychiatric disorders, and painful pathologies. Drawing from surveys, patient studies, and clinical trials, it highlights the potential of cannabis in alleviating symptoms, slowing disease progression, and improving overall quality of life for patients. Understanding the diverse therapeutic mechanisms of cannabis can open up possibilities for using this plant for individual patient needs.

Phytotherapeutic options for the treatment of epilepsy: pharmacology, targets, and mechanism of action

Epilepsy is one of the most common, severe, chronic, potentially life-shortening neurological disorders, characterized by a persisting predisposition to generate seizures. It affects more than 60 million individuals globally, which is one of the major burdens in seizure-related mortality, comorbidities, disabilities, and cost. Different treatment options have been used for the management of epilepsy. More than 30 drugs have been approved by the US FDA against epilepsy. However, one-quarter of epileptic individuals still show resistance to the current medications. About 90% of individuals in low and middle-income countries do not have access to the current medication. In these countries, plant extracts have been used to treat various diseases, including epilepsy. These medicinal plants have high therapeutic value and contain valuable phytochemicals with diverse biomedical applications. Epilepsy is a multifactorial disease, and therefore, multitarget approaches such as plant extracts or extracted phytochemicals are needed, which can target multiple pathways. Numerous plant extracts and phytochemicals have been shown to treat epilepsy in various animal models by targeting various receptors, enzymes, and metabolic pathways. These extracts and phytochemicals could be used for the treatment of epilepsy in humans in the future; however, further research is needed to study the exact mechanism of action, toxicity, and dosage to reduce their side effects. In this narrative review, we comprehensively summarized the extracts of various plant species and purified phytochemicals isolated from plants, their targets and mechanism of action, and dosage used in various animal models against epilepsy.

Investigating the Effects of Perampanel on Autophagy-mediated Regulation of GluA2 and PSD95 in Epilepsy

Epilepsy is a chronic neurological disorder characterized by recurrent seizures. Despite various treatment approaches, a significant number of patients continue to experience uncontrolled seizures, leading to refractory epilepsy. The emergence of novel anti-epileptic drugs, such as perampanel (PER), has provided promising options for effective epilepsy treatment. However, the specific mechanisms underlying the therapeutic effects of PER remain unclear. This study aimed to investigate the intrinsic molecular regulatory mechanisms involved in the downregulation of GluA2, a key subunit of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors, following epileptic seizures. Primary mouse hippocampal neurons were cultured and subjected to an epilepsy cell model. The expression levels of GluA2 and autophagy-related proteins were assessed using Western blotting and real-time fluorescent quantitative PCR. Immunofluorescence and immunohistochemistry techniques were employed to investigate the nuclear translocation of CREB-regulated transcriptional coactivator 1 (CRTC1). Additionally, status epilepticus animal models were established to further validate the findings. The epilepsy cell model exhibited a significant decrease in GluA2 expression, accompanied by elevated levels of autophagy-related proteins. Immunofluorescence analysis revealed the nuclear translocation of CRTC1, which correlated with the expression of autophagy-related genes. Treatment with an autophagy inhibitor reversed the decreased expression of GluA2 in the epilepsy cell model. Furthermore, the calcium/calmodulin-dependent protein phosphatase inhibitor FK506 and CaN overexpression affected the dephosphorylation and nuclear translocation of CRTC1, consequently influencing GluA2 expression. Animal model results further supported the involvement of these molecular mechanisms in epilepsy. Our findings suggest that the downregulation of GluA2 following epileptic seizures involves the activation of autophagy and the regulation of CRTC1 nuclear translocation. These intrinsic molecular regulatory mechanisms provide potential targets for developing novel therapeutic strategies to alleviate refractory epilepsy and preserve cognitive functions in patients.

Inhibition of neuronal pentraxin 2 relieved epileptic seizure via reducing GluA1 phosphorylation

Neuronal pentraxin 2 (Nptx2), a member of the synaptic protein family linked to excitatory synaptic formation, is found to be upregulated in epileptic mice, yet its role in epilepsy has been unclear. In vivo, we constructed a mouse model of epilepsy by using kainic acid induction. In vitro experiments, a Mg2+-free medium was used to induce epileptiform discharges in neurons. The results showed that the Nptx2 was upregulated in epileptic mice. Moreover, Nptx2 knockdown reduced the number of seizures and seizure duration. Knocking down Nptx2 not only reduced the number and duration of seizures but also showed a decrease in electroencephalogram amplitude. Behavioral tests indicated improvements in learning and memory abilities after Nptx2 knockdown. The Nissl staining and Timms staining revealed that Nptx2 silencing mitigated epilepsy-induced brain damage. The immunofluorescence staining revealed that Nptx2 absence resulted in a reduction of apoptosis. Nptx2 knockdown reduced Bax, cleaved caspase3, and cleaved caspase9 expression, while increased Bcl-2 expression. Notably, Nptx2 knockdown inhibited GluA1 phosphorylation at the S831 site and reduced the GluA1 membrane expression. The PSD95 expression declined in the epilepsy model, while the Nptx2 knockdown reversed it. Collectively, our study indicated that Nptx2 silencing not only alleviated brain damage and neuron apoptosis but also improved learning and memory ability in epileptic mice, suggesting Nptx2 as a promising target for epilepsy treatment.

In silico investigation of potential phytoconstituents against ligand- and voltage-gated ion channels as antiepileptic agents

The most promising anticonvulsant phytocompounds were explored in this work using docking, molecular dynamic (MD) simulation, and Molecular Mechanics-Poisson-Boltzmann Surface Area (MM-PBSA) approaches. A total of 70 phytochemicals were screened against α-amino-3-hydroxyl-5-methyl-4-isoxazole propionic acid (AMPA), N-methyl-d-aspartate (NMDA), voltage-gated sodium ion channels (VGSC), and carbonic anhydrase enzyme II (CA II) receptors, and the docking results were compared to the reference drug phenytoin. Amentoflavone displayed the highest affinity for AMPA and VGSC receptors, with docking scores of - 10.4 and - 10.1 kcal/mol, respectively. Oliganthin H-NMDA and epigallocatechin-3-gallate-CA II complexes showed docking scores of - 10.9 and - 6.9 kcal/mol, respectively. All four complexes depicted a high dock score compared to the phenytoin complex at the binding site of the corresponding proteins. The MD simulation investigated the stabilities and favorable conformation of apoproteins and ligand/reference-bound complexes. The results revealed that proteins AMPA, VGSC, and CA II were more efficiently stabilized by lead phytochemicals than phenytoin binding. Additionally, principal component analysis and MM-PBSA results suggested that these lead phytocompounds have good compactness and strong binding free energy. Further, physicochemical and pharmacokinetic studies revealed that these final lead phytochemicals would be suitable for oral intake, have sufficient intestinal permeability, and have the ability to cross the blood-brain barrier (BBB). Comprehensively, this study predicted amentoflavone as the best lead phytochemical out of the 70 anticonvulsant phytocompounds that can be used to treat epilepsy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03948-1.

Pharmacological characterization of SAGE-718, a novel positive allosteric modulator of N-methyl-d-aspartate receptors

BACKGROUND AND PURPOSE

Select neuroactive steroids tune neural activity by modulating excitatory and inhibitory neurotransmission, including the endogenous cholesterol metabolite 24(S)-hydroxycholesterol (24(S)-HC), which is an N-methyl-d-aspartate (NMDA) receptor positive allosteric modulator (PAM). NMDA receptor PAMs are potentially an effective pharmacotherapeutic strategy to treat conditions associated with NMDA receptor hypofunction.

EXPERIMENTAL APPROACH

Using in vitro and in vivo electrophysiological recording experiments and behavioural approaches, we evaluated the effect of SAGE-718, a novel neuroactive steroid NMDA receptor PAM currently in clinical development for the treatment of cognitive impairment, on NMDA receptor function and endpoints that are altered by NMDA receptor hypoactivity and assessed its safety profile.

KEY RESULTS

SAGE-718 potentiated GluN1/GluN2A-D NMDA receptors with equipotency and increased NMDA receptor excitatory postsynaptic potential (EPSP) amplitude without affecting decay kinetics in striatal medium spiny neurons. SAGE-718 increased the rate of unblock of the NMDA receptor open channel blocker ketamine on GluN1/GluN2A in vitro and accelerated the rate of return on the ketamine-evoked increase in gamma frequency band power, as measured with electroencephalogram (EEG), suggesting that PAM activity is driven by increased channel open probability. SAGE-718 ameliorated deficits due to NMDA receptor hypofunction, including social deficits induced by subchronic administration of phencyclidine, and behavioural and electrophysiological deficits from cholesterol and 24(S)-HC depletion caused by 7-dehydrocholesterol reductase inhibition. Finally, SAGE-718 did not produce epileptiform activity in a seizure model or neurodegeneration following chronic dosing.

CONCLUSIONS AND IMPLICATIONS

These findings provide strong evidence that SAGE-718 is a neuroactive steroid NMDA receptor PAM with a mechanism that is well suited as a treatment for conditions associated with NMDA receptor hypofunction.

The role of extracellular glutamate homeostasis dysregulated by astrocyte in epileptic discharges: a model evidence

Glutamate (Glu) is a predominant excitatory neurotransmitter that acts on glutamate receptors to transfer signals in the central nervous system. Abnormally elevated extracellular glutamate levels is closely related to the generation and transition of epileptic seizures. However, there lacks of investigation regarding the role of extracellular glutamate homeostasis dysregulated by astrocyte in neuronal epileptic discharges. According to this, we propose a novel neuron-astrocyte computational model (NAG) by incorporating extracellular Glu concentration dynamics from three aspects of regulatory mechanisms: (1) the Glu uptake through astrocyte EAAT2; (2) the binding and release Glu via activating astrocyte mGluRs; and (3) the Glu free diffusion in the extracellular space. Then the proposed model NAG is analyzed theoretically and numerically to verify the effect of extracellular Glu homeostasis dysregulated by such three regulatory mechanisms on neuronal epileptic discharges. Our results demonstrate that the neuronal epileptic discharges can be aggravated by the downregulation expression of EAAT2, the aberrant activation of mGluRs, and the elevated Glu levels in extracellular micro-environment; as well as various discharge states (including bursting, mixed-mode spiking, and tonic firing) can be transited by their combination. Furthermore, we find that such factors can also alter the bifurcation threshold for the generation and transition of epileptic discharges. The results in this paper can be helpful for researchers to understand the astrocyte role in modulating extracellular Glu homeostasis, and provide theoretical basis for future related experimental studies.

Latest advances in mechanisms of epileptic activity in Alzheimer's disease and dementia with Lewy Bodies

Alzheimer's disease (AD) and dementia with Lewy bodies (DLB) stand as the prevailing sources of neurodegenerative dementia, impacting over 55 million individuals across the globe. Patients with AD and DLB exhibit a higher prevalence of epileptic activity compared to those with other forms of dementia. Seizures can accompany AD and DLB in early stages, and the associated epileptic activity can contribute to cognitive symptoms and exacerbate cognitive decline. Aberrant neuronal activity in AD and DLB may be caused by several mechanisms that are not yet understood. Hyperexcitability could be a biomarker for early detection of AD or DLB before the onset of dementia. In this review, we compare and contrast mechanisms of network hyperexcitability in AD and DLB. We examine the contributions of genetic risk factors, Ca2+ dysregulation, glutamate, AMPA and NMDA receptors, mTOR, pathological amyloid beta, tau and α-synuclein, altered microglial and astrocytic activity, and impaired inhibitory interneuron function. By gaining a deeper understanding of the molecular mechanisms that cause neuronal hyperexcitability, we might uncover therapeutic approaches to effectively ease symptoms and slow down the advancement of AD and DLB.

Intrinsic brain activity differences in perampanel-responsive and non-responsive drug-resistant epilepsy patients: an EEG microstate analysis

Background

Drug-resistant epilepsy (DRE) patients exhibit aberrant large-scale brain networks. Perampanel may be a therapeutic option for controlling seizures in these patients.

Objective

We aim to explore the differences of resting-state electroencephalogram (EEG) microstate in perampanel-responsive and non-responsive DRE patients.

Design

Retrospective study.

Methods

Clinical data were collected from DRE patients who received perampanel treatment at the Fujian Medical University Union Hospital from June 2020 to September 2021, with a minimum follow-up of 6 months. Patients were classified into three groups based on the extent of reduction in seizure frequency: non-responsive (seizure reduction <50%), responsive (seizure reduction >50% but not seizure-free), and seizure-free. Resting-state EEG data sets of all participants were subjected to EEG microstate analysis. The study comprehensively compared the mean duration, frequency per second, and temporal coverage of each microstate among the three groups.

Results

A total of 76 perampanel-treated DRE patients were categorized into three groups based on their response to treatment: non-responsive (n = 20), responsive (n = 36), and seizure-free (n = 20), according to the degree of seizure frequency reduction. The results of EEG microstate analysis revealed no statistically significant distinctions in frequency, duration, and coverage of microstate D in these DRE patients. However, the seizure-free group showed significantly increased duration and coverage of microstate A, frequency and coverage of microstate B, and significantly decreased duration, frequency, and coverage of microstate C when compared with the other groups.

Conclusion

Microstate A, B, and D is associated with the sensorimotor network, visual network, salience network, and attention network, respectively. This study demonstrates statistically significant differences in the sensorimotor, visual, and salience networks, but not in the attention network, between perampanel-responsive and non-responsive DRE patients.

Origanum majorana L. polyphenols: in vivo antiepileptic effect, in silico evaluation of their bioavailability, and interaction with the NMDA receptor

Introduction: Epilepsy is a chronic brain disease characterized by repeated seizures and caused by excessive glutamate receptor activation. Many plants are traditionally used in the treatment of this disease. This study aimed to evaluate the bioavailability of a polyphenolic extract obtained from Origanum majorana L. (OMP) leaves, as well as its antiepileptic activity and its potential mechanism of action. Methods: We have developed and validated a simple, rapid, and accurate stability-indicating reversed-phase liquid chromatographic method for the simultaneous determination of caffeine and quercetin in rat plasma. The OMP antiepileptic effect was evaluated with pilocarpine-induced seizures, and a docking method was used to determine the possible interaction between caffeic acid and quercetin with the N-methyl-D-aspartate (NMDA) receptor. Results and Discussion: Both compounds tested showed low bioavailability in unchanged form. However, the tested extract showed an anticonvulsant effect due to the considerably delayed onset of seizures in the pilocarpine model at a dose of 100 mg/kg. The molecular docking proved a high-affinity interaction between the caffeic acid and quercetin with the NMDA receptor. Taken together, OLP polyphenols demonstrated good antiepileptic activity, probably due to the interaction of quercetin, caffeic acid, or their metabolites with the NMDA receptor.

Sex Differences in Organophosphate Model of Benzodiazepine-Refractory Status Epilepticus and Neuronal Damage

Sex differences are common in human epilepsy. Although men are more susceptible to seizure than women, the mechanisms underlying sex-specific vulnerabilities to seizure are unclear. The organophosphate (OP) diisopropylfluorophosphate (DFP) is known to cause neurotoxicity and status epilepticus (SE), a serious neurologic condition that causes prolonged seizures and brain damage. Current therapies for OP poisoning and SE do not consider neuronal variations between male and female brains. Therefore, we investigated sex-dependent differences in electrographic seizure activity and neuronal injury using the DFP model of refractory SE in rats. Electroencephalogram recordings were used to monitor DFP-induced SE, and the extent of brain injury was determined using fluoro-jade-B staining to detect cellular necrosis. After DFP exposure, we observed striking sex-dependent differences in SE and seizure activity patterns as well as protective responses to midazolam treatment. Following acute DFP exposure, male animals displayed more severe SE with intense epileptiform spiking and greater mortality than females. In contrast, we observed significantly more injured cells and cellular necrosis in the hippocampus and other brain regions in females than in males. We also observed extensive neuronal injury in the somatosensory cortex of males. The anticonvulsant effect of midazolam against SE was limited in this model and found to be similar in males and females. However, unlike males, females exhibited substantially more protection against neuronal damage after midazolam treatment. Overall, these results demonstrate significant sex-dependent differences in DFP-induced refractory SE and neuronal damage patterns, suggesting that it may be possible to develop sex-specific neuroprotective strategies for OP intoxication and refractory SE. SIGNIFICANCE STATEMENT: Sex-dependent differences in neurotoxicity and status epilepticus (SE) are key biological variables after organophosphate (OP) exposure. Here, we investigated sex-dependent differences in SE and brain injury after acute diisopropylfluorophosphate exposure. Male rats had more severe SE and less survival than females, while females had more neuronal damage. Females had more neuroprotection to midazolam than males, while both sexes had similar but partial anticonvulsant effects. These findings suggest that a sex-specific therapeutic approach may prevent neurological complications of OP-induced SE.

Pathophysiology to Risk Factor and Therapeutics to Treatment Strategies on Epilepsy

Epilepsy represents a condition in which abnormal neuronal discharges or the hyperexcitability of neurons occur with synchronicity, presenting a significant public health challenge. Prognostic factors, such as etiology, electroencephalogram (EEG) abnormalities, the type and number of seizures before treatment, as well as the initial unsatisfactory effects of medications, are important considerations. Although there are several third-generation antiepileptic drugs currently available, their multiple side effects can negatively affect patient quality of life. The inheritance and etiology of epilepsy are complex, involving multiple underlying genetic and epigenetic mechanisms. Different neurotransmitters play crucial roles in maintaining the normal physiology of different neurons. Dysregulations in neurotransmission, due to abnormal transmitter levels or changes in their receptors, can result in seizures. In this review, we address the roles played by various neurotransmitters and their receptors in the pathophysiology of epilepsy. Furthermore, we extensively explore the neurological mechanisms involved in the development and progression of epilepsy, along with its risk factors. Furthermore, we highlight the new therapeutic targets, along with pharmacological and non-pharmacological strategies currently employed in the treatment of epileptic syndromes, including drug interventions employed in clinical trials related to epilepsy.

Expression and Purification of Mammalian NMDA Receptor Protein for Functional Characterization

N-methyl-D-aspartate (NMDA) receptors are critical for brain function and serve as drug targets for the treatment of neurological and psychiatric disorders. They typically form the tetrameric assembly of GluN1-GluN2 (2A to 2D) subtypes, with their diverse three-dimensional conformations linked with the physiologically relevant function in vivo. Purified proteins of tetrameric assembled NMDA receptors have broad applications in the structural elucidation, hybridoma technology for antibody production, and high-throughput drug screening. However, obtaining sufficient quantity and monodisperse NMDA receptor protein is still technically challenging. Here, we summarize a paradigm for the expression and purification of diverse NMDA receptor subtypes, with detailed descriptions on screening constructs by fluorescence size-exclusion chromatography (FSEC), generation of recombinant baculovirus, expression in the eukaryotic expression system, protein purification by affinity chromatography and size-exclusion chromatography (SEC), biochemical and functional validation assays.

Spectrum of NMDA Receptor Variants in Neurodevelopmental Disorders and Epilepsy

N-methyl-D-aspartate receptors (NMDAR) are ligand-gated ion channels mediating excitatory neurotransmission and are important for normal brain development, cognitive abilities, and motor functions. Pathogenic variants in the Glutamate receptor Ionotropic N-methyl-D-aspartate (GRIN) genes (GRIN1, GRIN2A-D) encoding NMDAR subunits have been associated with a wide spectrum of neurodevelopmental disorders and epilepsies ranging from treatable focal epilepsies to devastating early-onset developmental and epileptic encephalopathies. Genetic variants in NMDA receptor genes can cause a range of complex alterations to receptor properties resulting in various degrees of loss-of-function, gain-of-function, or mixtures thereof. Understanding how genetic variants affect the function of the receptors, therefore, represents an important first step in the ongoing development towards targeted therapies. Currently, targeted treatment options for GRIN-related diseases are limited. However, treatment with memantine has been reported to significantly reduce seizure frequency in a few individuals with developmental and epileptic encephalopathies harboring de novo gain-of-function GRIN2A missense variants, and supplementary treatment with L-serine has been associated with improved motor and cognitive performance as well as reduced seizure frequency in patients with GRIN2B loss-of-function missense variants as well as GRIN2A and GRIN2B null variants.

Glutamate Receptors and C-ABL Inhibitors: A New Therapeutic Approach for Parkinson's Disease

Parkinson's disease (PD) is the second-most prevalent central nervous system (CNS) neurodegenerative condition. Over the past few decades, suppression of BCR-Abelson tyrosine kinase (c-Abl), which serves as a marker of -synuclein aggregation and oxidative stress, has shown promise as a potential therapy target in PD. c-Abl inhibition has the potential to provide neuroprotection against PD, as shown by experimental results and the first-in-human trial, which supports the strategy in bigger clinical trials. Furthermore, glutamate receptors have also been proposed as potential therapeutic targets for the treatment of PD since they facilitate and regulate synaptic neurotransmission throughout the basal ganglia motor system. It has been noticed that pharmacological manipulation of the receptors can change normal as well as abnormal neurotransmission in the Parkinsonian brain. The review study contributes to a comprehensive understanding of the approach toward the role of c-Abl and glutamate receptors in Parkinson's disease by highlighting the significance and urgent necessity to investigate new pharmacotherapeutic targets. The article covers an extensive insight into the concept of targeting, pathophysiology, and c-Abl interaction with α-synuclein, parkin, and cyclin-dependent kinase 5 (Cdk5). Furthermore, the concepts of Nmethyl- D-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPA) receptor, and glutamate receptors are discussed briefly. Conclusion: This review article focuses on in-depth literature findings supported by an evidence-based discussion on pre-clinical trials and clinical trials related to c-Abl and glutamate receptors that act as potential therapeutic targets for PD.

Inhibitory dysfunction and social processing difficulties in autism: A comprehensive narrative review

The primary inhibitory neurotransmitter γ-aminobutyric acid (GABA) has a prominent role in regulating neural development and function, with disruption to GABAergic signalling linked to behavioural phenotypes associated with neurodevelopmental disorders, particularly autism. Such neurochemical disruption, likely resulting from diverse genetic and molecular mechanisms, particularly during early development, can subsequently affect the cellular balance of excitation and inhibition in neuronal circuits, which may account for the social processing difficulties observed in autism and related conditions. This comprehensive narrative review integrates diverse streams of research from several disciplines, including molecular neurobiology, genetics, epigenetics, and systems neuroscience. In so doing it aims to elucidate the relevance of inhibitory dysfunction to autism, with specific focus on social processing difficulties that represent a core feature of this disorder. Many of the social processing difficulties experienced in autism have been linked to higher levels of the excitatory neurotransmitter glutamate and/or lower levels of inhibitory GABA. While current therapeutic options for social difficulties in autism are largely limited to behavioural interventions, this review highlights the psychopharmacological studies that explore the utility of GABA modulation in alleviating such difficulties.

Hydrogel and Nanomedicine-Based Multimodal Therapeutic Strategies for Spinal Cord Injury

Spinal cord injury (SCI) is a severe neurodegenerative disease caused by mechanical and biological factors, manifesting as a loss of motor and sensory functions. Inhibition of injury expansion and even reversal of injury in the acute damage stage of SCI are important strategies for treating this disease. Hydrogels and nanoparticle (NP)-based drugs are the most effective, widely studied, and clinically valuable therapeutic strategies in the field of repair and regeneration. Hydrogels are 3D flow structures that fill the pathological gaps in SCI and provide a microenvironment similar to that of the spinal cord extracellular matrix for nerve cell regeneration. NP-based drugs can easily penetrate the blood-spinal cord barrier, target SCI lesions, and are noninvasive. Hydrogels and NPs as drug carriers can be loaded with various drugs and biological therapeutic factors for slow release in SCI lesions. They help drugs function more efficiently by exerting anti-inflammatory, antioxidant, and nerve regeneration effects to promote the recovery of neurological function. In this review, the use of hydrogels and NPs as drug carriers and the role of both in the repair of SCI are discussed to provide a multimodal strategic reference for nerve repair and regeneration after SCI.

Efficacy of Perampanel in Refractory and Super-Refractory Status Epilepticus with Suspected Inflammatory Etiology: A Case Series

(1) Background: Increasing evidence supports the anti-inflammatory and neuroprotective role of perampanel (PER), mediated by decreased expression of pro-inflammatory cytokines and by interference with apoptosis processes. Therefore, the use of PER to treat status epilepticus (SE) with suspected inflammatory etiology is appealing and deserves further investigation. (2) Methods: We retrospectively analyzed seven patients (five F, two M; median age: 62 years) with refractory and super-refractory SE due to a probable or defined inflammatory etiology and treated with PER. (3) Results: PER was administered as the third (4/7) or fourth drug (3/7), with a median loading dose of 32 mg/day (range: 16-36 mg/day) and a median maintenance dose of 10 mg/day (range: 4-12 mg/day). In five cases, SE was focal, while in two patients, it was generalized. SE was caused by systemic inflammation in three patients, while in the other four subjects, it was recognized to have an autoimmune etiology. SE resolution was observed after PER administration in all cases, particularly within 24 h in the majority of patients (4/7, 57.1%). (4) Conclusions: Our data support the efficacy of PER in treating SE when first- and second-line ASMs have failed and suggest a possible earlier use in SE cases that are due to inflammatory/autoimmune etiology.

Molecular Mechanisms of AMPA Receptor Trafficking in the Nervous System

Synaptic plasticity enhances or reduces connections between neurons, affecting learning and memory. Postsynaptic AMPARs mediate greater than 90% of the rapid excitatory synaptic transmission in glutamatergic neurons. The number and subunit composition of AMPARs are fundamental to synaptic plasticity and the formation of entire neural networks. Accordingly, the insertion and functionalization of AMPARs at the postsynaptic membrane have become a core issue related to neural circuit formation and information processing in the central nervous system. In this review, we summarize current knowledge regarding the related mechanisms of AMPAR expression and trafficking. The proteins related to AMPAR trafficking are discussed in detail, including vesicle-related proteins, cytoskeletal proteins, synaptic proteins, and protein kinases. Furthermore, significant emphasis was placed on the pivotal role of the actin cytoskeleton, which spans throughout the entire transport process in AMPAR transport, indicating that the actin cytoskeleton may serve as a fundamental basis for AMPAR trafficking. Additionally, we summarize the proteases involved in AMPAR post-translational modifications. Moreover, we provide an overview of AMPAR transport and localization to the postsynaptic membrane. Understanding the assembly, trafficking, and dynamic synaptic expression mechanisms of AMPAR may provide valuable insights into the cognitive decline associated with neurodegenerative diseases.

Socrates: A Novel N-Ethyl-N-nitrosourea-Induced Mouse Mutant with Audiogenic Epilepsy

Epilepsy is one of the common neurological diseases that affects not only adults but also infants and children. Because epilepsy has been studied for a long time, there are several pharmacologically effective anticonvulsants, which, however, are not suitable as therapy for all patients. The genesis of epilepsy has been extensively investigated in terms of its occurrence after injury and as a concomitant disease with various brain diseases, such as tumors, ischemic events, etc. However, in the last decades, there are multiple reports that both genetic and epigenetic factors play an important role in epileptogenesis. Therefore, there is a need for further identification of genes and loci that can be associated with higher susceptibility to epileptic seizures. Use of mouse knockout models of epileptogenesis is very informative, but it has its limitations. One of them is due to the fact that complete deletion of a gene is not, in many cases, similar to human epilepsy-associated syndromes. Another approach to generating mouse models of epilepsy is N-Ethyl-N-nitrosourea (ENU)-directed mutagenesis. Recently, using this approach, we generated a novel mouse strain, soc (socrates, formerly s8-3), with epileptiform activity. Using molecular biology methods, calcium neuroimaging, and immunocytochemistry, we were able to characterize the strain. Neurons isolated from soc mutant brains retain the ability to differentiate in vitro and form a network. However, soc mutant neurons are characterized by increased spontaneous excitation activity. They also demonstrate a high degree of Ca2+ activity compared to WT neurons. Additionally, they show increased expression of NMDA receptors, decreased expression of the Ca2+-conducting GluA2 subunit of AMPA receptors, suppressed expression of phosphoinositol 3-kinase, and BK channels of the cytoplasmic membrane involved in protection against epileptogenesis. During embryonic and postnatal development, the expression of several genes encoding ion channels is downregulated in vivo, as well. Our data indicate that soc mutation causes a disruption of the excitation-inhibition balance in the brain, and it can serve as a mouse model of epilepsy.

In vitro protective effect of recombinant prominin-1 combined with microRNA-29b on N-methyl-D-aspartate-induced excitotoxicity in retinal ganglion cells

AIM

To determine the in vitro protective effect of recombinant prominin-1 (Prominin-1)+microRNA-29b (P1M29) on N-methyl-D-aspartate (NMDA)-induced excitotoxicity in retinal ganglion cells (RGCs).

METHODS

RGC-5 cells were cultured, and NMDA-induced excitotoxicity at the range of 100-800 µmol/L was assessed using the MTT assay. NMDA (800 µmol/L) was selected as the appropriate concentration for preparing the cell model. To evaluate the protective effect of P1M29 on the cell model, Prominin-1 was added at the concentration of 1-6 ng/mL for 48h, and the cell survival was investigated with/without microRNA-29b. After obtaining the appropriate concentration and time of P1M29 at 48h, real-time polymerase chain reaction (PCR) was utilized to detect the relative mRNA expression of vascular endothelial growth factor (VEGF) and transforming growth factor (TGF)-β2. Western blot detection was applied to measure the phosphorylation levels of protein kinase B (AKT) and extracellular regulated protein kinases (ERK) in RGC-5 cells after treatment with Prominin-1. Apoptosis study of the cell model was conducted by flow cytometry for estimating the anti-apoptotic effect of P1M29. Immunofluorescence analysis was used to analyze the expression levels of VEGF and TGF-β2.

RESULTS

MTT cytotoxicity assays demonstrated that P1M29 group had significantly higher cell survival rate than Prominin-1 group (P<0.05). Real-time PCR data indicated that the expression levels of VEGF were significantly increased in both Prominin-1 and P1M29 groups compared NMDA and microRNA-29b group (P<0.05), while TGF-β2 were significantly decreased in both microRNA-29b and P1M29 groups compared NMDA and Prominin-1 group (P<0.05). Western blot results showed that both Prominin-1 and P1M29 groups significantly increased the phosphorylation levels of AKT and ERK compared to NMDA and microRNA-29b groups (P<0.05). Flow cytometry analysis revealed that P1M29 could prevent RGC-5 cell apoptosis in the early stage of apoptosis, while immunofluorescence results showed that P1M29 group had higher expression of VEGF and lower expression of TGF-β2 with a stronger green fluorescence than NMDA group.

CONCLUSION

Prominin-1 combined with microRNA-29b can provide a suitable therapeutic option for ameliorating NMDA-induced excitotoxicity in RGC-5 cells.

Genetic Background of Epilepsy and Antiepileptic Treatments

Advanced identification of the gene mutations causing epilepsy syndromes is expected to translate into faster diagnosis and more effective treatment of these conditions. Over the last 5 years, approximately 40 clinical trials on the treatment of genetic epilepsies have been conducted. As a result, some medications that are not regular antiseizure drugs (e.g., soticlestat, fenfluramine, or ganaxolone) have been introduced to the treatment of drug-resistant seizures in Dravet, Lennox-Gastaut, maternally inherited chromosome 15q11.2-q13.1 duplication (Dup 15q) syndromes, and protocadherin 19 (PCDH 19)-clusterig epilepsy. And although the effects of soticlestat, fenfluramine, and ganaxolone are described as promising, they do not significantly affect the course of the mentioned epilepsy syndromes. Importantly, each of these syndromes is related to mutations in several genes. On the other hand, several mutations can occur within one gene, and different gene variants may be manifested in different disease phenotypes. This complex pattern of inheritance contributes to rather poor genotype-phenotype correlations. Hence, the detection of a specific mutation is not synonymous with a precise diagnosis of a specific syndrome. Bearing in mind that seizures develop as a consequence of the predominance of excitatory over inhibitory processes, it seems reasonable that mutations in genes encoding sodium and potassium channels, as well as glutamatergic and gamma-aminobutyric (GABA) receptors, play a role in the pathogenesis of epilepsy. In some cases, different pathogenic variants of the same gene can result in opposite functional effects, determining the effectiveness of therapy with certain medications. For instance, seizures related to gain-of-function (GoF) mutations in genes encoding sodium channels can be successfully treated with sodium channel blockers. On the contrary, the same drugs may aggravate seizures related to loss-of-function (LoF) variants of the same genes. Hence, knowledge of gene mutation-treatment response relationships facilitates more favorable selection of drugs for anticonvulsant therapy.

Acute inhibition of AMPA receptors by perampanel reduces amyloid β-protein levels by suppressing β-cleavage of APP in Alzheimer's disease models

Hippocampal hyperexcitability is a promising therapeutic target to prevent Aβ deposition in AD since enhanced neuronal activity promotes presynaptic Aβ production and release. This article highlights the potential application of perampanel (PER), an AMPA receptor (AMPAR) antagonist approved for partial seizures, as a therapeutic agent for AD. Using transgenic AD mice combined with in vivo brain microdialysis and primary neurons under oligomeric Aβ-evoked neuronal hyperexcitability, the acute effects of PER on Aβ metabolism were investigated. A single oral administration of PER rapidly decreased ISF Aβ40 and Aβ42 levels in the hippocampus of J20, APP transgenic mice, without affecting the Aβ40 /Aβ42 ratio; 5 mg/kg PER resulted in declines of 20% and 31%, respectively. Moreover, PER-treated J20 manifested a marked decrease in hippocampal APP βCTF levels with increased FL-APP levels. Consistently, acute treatment of PER reduced sAPPβ levels, a direct byproduct of β-cleavage of APP, released to the medium in primary neuronal cultures under oligomeric Aβ-induced neuronal hyperexcitability. To further evaluate the effect of PER on ISF Aβ clearance, a γ-secretase inhibitor was administered to J20 1 h after PER treatment. PER did not influence the elimination of ISF Aβ, indicating that the acute effect of PER is predominantly on Aβ production. In conclusion, acute treatment of PER reduces Aβ production by suppressing β-cleavage of amyloid-β precursor protein effectively, indicating a potential effect of PER against Aβ pathology in AD.

Unveiling the functional diversity of ionotropic glutamate receptors in the Pacific oyster (Crassostrea gigas) by systematic studies

Ionotropic glutamate receptors (iGluRs), pivotal in mediating excitatory neurosignals within the central nervous system, are instrumental in environmental stress responses. In this investigation, 12 iGluRs identified in the Pacific oyster are herein designated as CgiGluRs, and further categorized into three distinct subfamilies based on their transmembrane domains. Cross-species evolutionary analysis unveiled a high degree of conservation in the sequence and structural attributes of these CgiGluRs. These receptors are ubiquitously distributed across various tissues, with pronounced expression in the oyster's mantle, labial palps, and gills, underlining their integral role in the oyster's environmental sensing mechanisms. Post the D-shaped larval stage, a marked upward trend in CgiGluRs expression was observed, denoting their critical involvement in oyster development beyond this phase. Exposure to five metals-cadmium (Cd), copper (Cu), zinc (Zn), mercury (Hg), and lead (Pb)-elicited a significant upregulation of CgGRIA4 expression, indicating a robust response to metal stress. A KEGG enrichment analysis on 142 genes, exhibiting parallel expression trends with CgGRIA4 under metal stress, suggests that CgGRIA4 could augment excitatory signal transmission by activating glutamatergic and dopaminergic synapses, thereby contributing to the metal stress response in the oyster. This inquiry not only bolsters our comprehension of the iGluRs gene family in metal stress response but also paves the way for future exploration of its cardinal role in cellular signaling and environmental adaptability.

Recent Progress in the Development of New Antiepileptic Drugs with Novel Targets

Background

Epilepsy is a chronic neurological disorder that affects approximately 50-70 million people worldwide. Epilepsy has a significant economic and social burden on patients as well as on the country. The recurrent, spontaneous seizure activity caused by abnormal neuronal firing in the brain is a hallmark of epilepsy. The current antiepileptic drugs provide symptomatic relief by restoring the balance of excitatory and inhibitory neurotransmitters. Besides, about 30% of epileptic patients do not achieve seizure control. The prevalence of adverse drug reactions, including aggression, agitation, irritability, and associated comorbidities, is also prevalent. Therefore, researchers should focus on developing more effective, safe, and disease-modifying agents based on new molecular targets and signaling cascades.

Summary

This review overviews several clinical trials that help identify promising new targets like lactate dehydrogenase inhibitors, c-jun n-terminal kinases, high mobility group box-1 antibodies, astrocyte reactivity inhibitors, cholesterol 24-hydroxylase inhibitors, glycogen synthase kinase-3 beta inhibitors, and glycolytic inhibitors to develop a new antiepileptic drug.

Key messages

Approximately 30% of epileptic patients do not achieve seizure control. The current anti-seizure drugs are not disease modifying, cure or prevent epilepsy. Lactate dehydrogenase inhibitor, cholesterol 24-hydroxylase inhibitor, glycogen synthase kinase-3 beta inhibitors, and mTOR inhibitors have a promising antiepileptogenic effect.

Mechanisms and Functions of Activity-Regulated Cytoskeleton-Associated Protein in Synaptic Plasticity

Activity-regulated cytoskeleton-associated protein (Arc) is one of the most important regulators of cognitive functions in the brain regions. As a hub protein, Arc plays different roles in modulating synaptic plasticity. Arc supports the maintenance of long-term potentiation (LTP) by regulating actin cytoskeletal dynamics, while it guides the endocytosis of AMPAR in long-term depression (LTD). Moreover, Arc can self-assemble into capsids, leading to a new way of communicating among neurons. The transcription and translation of the immediate early gene Arc are rigorous procedures guided by numerous factors, and RNA polymerase II (Pol II) is considered to regulate the precise timing dynamics of gene expression. Since astrocytes can secrete brain-derived neurotrophic factor (BDNF) and L-lactate, their unique roles in Arc expression are emphasized. Here, we review the entire process of Arc expression and summarize the factors that can affect Arc expression and function, including noncoding RNAs, transcription factors, and posttranscriptional regulations. We also attempt to review the functional states and mechanisms of Arc in modulating synaptic plasticity. Furthermore, we discuss the recent progress in understanding the roles of Arc in the occurrence of major neurological disorders and provide new thoughts for future research on Arc.

The Interplay between Mitochondrial Dysfunction and Ferroptosis during Ischemia-Associated Central Nervous System Diseases

Cerebral ischemia, a leading cause of disability and mortality worldwide, triggers a cascade of molecular and cellular pathologies linked to several central nervous system (CNS) disorders. These disorders primarily encompass ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, and other CNS conditions. Despite substantial progress in understanding and treating the underlying pathological processes in various neurological diseases, there is still a notable absence of effective therapeutic approaches aimed specifically at mitigating the damage caused by these illnesses. Remarkably, ischemia causes severe damage to cells in ischemia-associated CNS diseases. Cerebral ischemia initiates oxygen and glucose deprivation, which subsequently promotes mitochondrial dysfunction, including mitochondrial permeability transition pore (MPTP) opening, mitophagy dysfunction, and excessive mitochondrial fission, triggering various forms of cell death such as autophagy, apoptosis, as well as ferroptosis. Ferroptosis, a novel type of regulated cell death (RCD), is characterized by iron-dependent accumulation of lethal reactive oxygen species (ROS) and lipid peroxidation. Mitochondrial dysfunction and ferroptosis both play critical roles in the pathogenic progression of ischemia-associated CNS diseases. In recent years, growing evidence has indicated that mitochondrial dysfunction interplays with ferroptosis to aggravate cerebral ischemia injury. However, the potential connections between mitochondrial dysfunction and ferroptosis in cerebral ischemia have not yet been clarified. Thus, we analyzed the underlying mechanism between mitochondrial dysfunction and ferroptosis in ischemia-associated CNS diseases. We also discovered that GSH depletion and GPX4 inactivation cause lipoxygenase activation and calcium influx following cerebral ischemia injury, resulting in MPTP opening and mitochondrial dysfunction. Additionally, dysfunction in mitochondrial electron transport and an imbalanced fusion-to-fission ratio can lead to the accumulation of ROS and iron overload, which further contribute to the occurrence of ferroptosis. This creates a vicious cycle that continuously worsens cerebral ischemia injury. In this study, our focus is on exploring the interplay between mitochondrial dysfunction and ferroptosis, which may offer new insights into potential therapeutic approaches for the treatment of ischemia-associated CNS diseases.

Telaprevir Improves Memory and Cognition in Mice Suffering Ischemic Stroke via Targeting MALT1-Mediated Calcium Overload and Necroptosis

Mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) has been confirmed to contribute to brain injury in ischemic stroke via promoting excitotoxicity and necroptosis. Telaprevir, a hepatitis C virus protease inhibitor, is predicted to be a potential MALT1 inhibitor. Here, we showed that telaprevir protected against cerebral ischemic injury via inhibiting MALT1, thereby preventing glutamate receptor ionotropic NMDA 2B (GluN2B) activation, limiting calcium overload, and suppressing necroptosis. In ischemic stroke mice, telaprevir reduced infarct volume, improved the long-term survival rate, and enhanced sensorimotor, memory, and cognitive functions. In hypoxia-treated nerve cells, telaprevir decreased the intracellular calcium concentrations and reduced LDH release. Mechanistically, telaprevir inhibited MALT1 protease activity, thus decreasing the membrane protein level of GluN2B and its phosphorylation through reducing the level of STEP61. Moreover, telaprevir was able to inhibit the levels of necroptosis-associated proteins. According to these results, it can be concluded that telaprevir alleviates neuronal brain injury in stroke mice via restraining GluN2B activation and suppresses the receptor-interacting protein kinase 1 (RIPK1)/receptor-interacting protein kinase 3 (RIPK3)/mixed lineage kinase domain-like pseudokinase (MLKL) pathway through inhibiting MALT1. Thus, telaprevir might have a novel indication for treating patients with ischemic stroke.

Xenon inhalation attenuates neuronal injury and prevents epilepsy in febrile seizure Sprague-Dawley pups

Background

Febrile seizures (FS) usually occur in childhood and may cause irreversible neuronal damage, cognitive functional defects, and an increase in the risk of epilepsy later in life. Anti-epileptic drugs (AEDs), currently used to treat FS in children, can relieve seizures. However, their effects in preventing the risk of developing epilepsy in later life are unsatisfactory. Moreover, AEDs may damage child brain development. Here, we evaluated the efficiency of xenon in treating prolonged FS (PFS) and preventing epilepsy in Sprague-Dawley pups.

Methods

Prolonged FS was induced by hyperthermic treatment. After 90 min of PFS, the pups in the xenon treatment group were immediately treated with 70% xenon/21% oxygen/9% nitrogen for 60 min. The levels of glutamate, mitochondrial oxidative stress, mitophagy, and neuronal injury, seizures, learning, and memory functions were measured at specific time points.

Results

Neonatal period PFS led to spontaneous seizure, learning and memory dysfunction, accompanied by increased levels of glutamate, mitochondrial oxidative stress, mitophagy, and neuronal injury. Xenon treatment alleviated the changes caused by PFS and reduced the risk of PFS developing into epilepsy later.

Conclusion

Our results suggest that xenon inhalation could be a potential therapeutic strategy to attenuate neuronal injury and prevent epilepsy in patients with FS.

Transition metal ions and neurotransmitters: coordination chemistry and implications for neurodegeneration

Neurodegeneration is characterized by a disturbance in neurotransmitter-mediated signaling pathways. Recent studies have highlighted the significant role of transition metal ions, including Cu(i/ii), Zn(ii), and Fe(ii/iii), in neurotransmission, thereby making the coordination chemistry of neurotransmitters a growing field of interest in understanding signal dysfunction. This review outlines the physiological functions of transition metal ions and neurotransmitters, with the metal-binding properties of small molecule-based neurotransmitters and neuropeptides. Additionally, we discuss the structural and conformational changes of neurotransmitters induced by redox-active metal ions, such as Cu(i/ii) and Fe(ii/iii), and briefly describe the outcomes arising from their oxidation, polymerization, and aggregation. These observations have important implications for neurodegeneration and emphasize the need for further research to develop potential therapeutic strategies.

Treating Epilepsy with Natural Products: Nonsense or Possibility?

Epilepsy is a neurological disease characterized by recurrent seizures that can lead to uncontrollable muscle twitching, changes in sensitivity to sensory perceptions, and disorders of consciousness. Although modern medicine has effective antiepileptic drugs, the need for accessible and cost-effective medication is urgent, and products derived from plants could offer a solution. For this review, we have focused on natural compounds that have shown anticonvulsant activity in in vivo models of epilepsy at relevant doses. In some cases, the effects have been confirmed by clinical data. The results of our search are summarized in tables according to their molecular targets. We have critically evaluated the data we present, identified the most promising therapeutic candidates, and discussed these in the text. Their perspectives are supported by both pharmacokinetic properties and potential interactions. This review is intended to serve as a basis for future research into epilepsy and related disorders.

An In Vivo Electroencephalographic Analysis of the Effect of Riluzole against Limbic and Absence Seizure and Comparison with Glutamate Antagonists

BACKGROUND

Riluzole (RLZ) has demonstrated neuroprotective effects in several neurological disorders. These neuroprotective effects seem to be mainly due to its ability to inhibit the excitatory glutamatergic neurotransmission, acting on different targets located both at the presynaptic and postsynaptic levels.

METHODS

In the present study, we evaluated the effects of Riluzole (RLZ) against limbic seizures, induced by AMPA, kainate, and NMDA receptor agonists in Sprague-Dawley rats, and in a well-validated genetic model of absence epilepsy, the WAG/Rij rat. Furthermore, in this latter model, we also studied the effect of RLZ in co-administration with the competitive NMDA receptor antagonist, CPP, or the non-competitive AMPA receptor antagonist, THIQ-10c, on spike-wave discharges (SWDs) in WAG/Rij rats, to understand the potential involvement of AMPA and NMDA receptors in the anti-absence effect of RLZ.

RESULTS

In Sprague-Dawley rats, RLZ pretreatment significantly reduced the limbic seizure severity induced by glutamatergic agonists, suggesting an antagonism of RLZ mainly on NMDA rather than non-NMDA receptors. RLZ also reduced SWD parameters in WAG/Rij rats. Interestingly, the co-administration of RLZ with CPP did not increase the anti-absence activity of RLZ in this model, advocating a competitive effect on the NMDA receptor. In contrast, the co-administration of RLZ with THIQ-10c induced an additive effect against absence seizure in WAG/Rij rats.

CONCLUSIONS

these results suggest that the antiepileptic effects of RLZ, in both seizure models, can be mainly due to the antagonism of the NMDA glutamatergic receptors.

The broad-spectrum activity of perampanel: state of the art and future perspective of AMPA antagonism beyond epilepsy

Glutamate is the brain's main excitatory neurotransmitter. Glutamatergic neurons primarily compose basic neuronal networks, especially in the cortex. An imbalance of excitatory and inhibitory activities may result in epilepsy or other neurological and psychiatric conditions. Among glutamate receptors, AMPA receptors are the predominant mediator of glutamate-induced excitatory neurotransmission and dictate synaptic efficiency and plasticity by their numbers and/or properties. Therefore, they appear to be a major drug target for modulating several brain functions. Perampanel (PER) is a highly selective, noncompetitive AMPA antagonist approved in several countries worldwide for treating different types of seizures in various epileptic conditions. However, recent data show that PER can potentially address many other conditions within epilepsy and beyond. From this perspective, this review aims to examine the new preclinical and clinical studies-especially those produced from 2017 onwards-on AMPA antagonism and PER in conditions such as mesial temporal lobe epilepsy, idiopathic and genetic generalized epilepsy, brain tumor-related epilepsy, status epilepticus, rare epileptic syndromes, stroke, sleep, epilepsy-related migraine, cognitive impairment, autism, dementia, and other neurodegenerative diseases, as well as provide suggestions on future research agenda aimed at probing the possibility of treating these conditions with PER and/or other AMPA receptor antagonists.

Anxiolytic-like effects of an mGluR 5 antagonist and a mGluR 2/3 agonist, and antidepressant-like effects of an mGluR 7 agonist in the chick social separation stress test, a dual-drug screening model of treatment-resistant depression

Modulation of glutamate receptors has demonstrated anxiolytic and/or antidepressant effects in rodent stress models. The chick social-separation stress paradigm exposes socially raised aves to an isolation stressor which elicits distress vocalizations (DVocs) in an attempt to re-establish contact. The model presents a state of panic during the first 5 min followed by a state of behavioral despair during the last 60 to 90 min. Making it useful as a dual anxiolytic/antidepressant screening assay. Further research has identified the Black Australorp strain as a stress-vulnerable, treatment-resistant, and ketamine-sensitive genetic line. Utilizing this genetic line, we sought to evaluate modulation of glutamatergic receptors for potential anxiolytic and/or antidepressant effects. Separate dose-response studies were conducted for the following drugs: the AMPA PAM LY392098, the mGluR 5 antagonist MPEP, the mGluR 2/3 agonist LY404039, the mGluR 2/3 antagonist LY341495, and the mGluR 7 agonist AMN082. The norepinephrine α² agonist clonidine and the NMDA antagonist ketamine were included as comparison for anxiolytic (anti-panic) and antidepressant effects, respectively. As in previous studies, clonidine reduced DVoc rates during the first 5 min (attenuation of panic) and ketamine elevated DVoc rates (attenuation of behavioral despair) during the last 60 min of isolation. The mGluR 2/3 agonist LY404039 and the mGluR 5 antagonist MPEP decreased DVoc rates during the first 5 min of isolation indicative of anxiolytic effects like that of clonidine while the mGluR 7 agonist AMN082 elevated DVoc rates in the later hour of isolation, representative of antidepressant effects like that of ketamine. Collectively, these findings suggest that certain glutamate targets may be clinically useful in treating panic disorder and/or treatment-resistant depression.

Mining and analysis of adverse drug reactions associated with perampanel based on FAERS database

INTRODUCTION

Perampanel (PER) is a non-competitive AMPA glutamate receptor antagonist used as an anti-seizure medication. Large post-marketing databases are still lacking for safety analysis of the new generation of anti-seizure medications. Based on the FDA's adverse event reporting system (FAERS) database, this study aimed to investigate, assess, and offer evidence for the safety of PER to support clinical decision-making.

METHODS

Perampanel-related adverse reaction signals were mined using the reporting odds ratio (ROR), medicines and healthcare products regulatory agency (MHRA), and Bayesian confidence propagation neural network (BCPNN). The rate and occurrence of reported adverse responses were examined.

RESULTS

With the three methodologies used in combination, 83 signals mostly related to psychosis and different nervous system disorders were detected. Among them, suicide behavior, respiratory depression, hepatotoxicity, cognitive impairment, and other possible novel signals warranted consideration. Further examination of the age and gender differences in the detected signals revealed that elderly patients should be closely monitored for any change in consciousness and the occurrence of movement disorders; male patients should be observed for negative mental reactions like a personal attack and homicidal ideation; and female patients should be watched for the occurrence of negative reactions in memory, weight, vision, liver function, and other specific areas.

CONCLUSIONS

This study found that PER had the risk of causing suicide behavior, respiratory depression, hepatotoxicity, and cognitive impairment among other adverse effects. When used clinically, PER should be closely monitored for the occurrence of adverse effects on mental health and behavior. However, these results should be interpreted with caution.

Sulfate-modified nanosized polystyrene impairs memory by inhibiting ionotropic glutamate receptors and the cAMP-response element binding protein (CREB) pathway in Caenorhabditis elegans

Nanoplastic contamination is an emerging environmental concern worldwide. In particular, sulfate anionic surfactants often appear along with nanosized plastic particles in personal care products, suggesting that sulfate-modified nanosized polystyrene (S-NP) may occur, remain, and spread into the environment. However, whether S-NP adversely affects learning and memory is unknown. In this study, we used a positive butanone training protocol to evaluate the effects of S-NP exposure on short-term associative memory (STAM) and long-term associative memory (LTAM) in Caenorhabditis elegans. We observed that long-term S-NP exposure impairs both STAM and LTAM in C. elegans. We also observed that mutations in the glr-1, nmr-1, acy-1, unc-43, and crh-1 genes eliminated the STAM and LTAM impairment induced by S-NP, and the mRNA levels of these genes were also decreased upon S-NP exposure. These genes encode ionotropic glutamate receptors (iGluRs), cyclic adenosine monophosphate (cAMP)/Ca²⁺ signaling proteins, and cAMP-response element binding protein (CREB)/CRH-1 signaling proteins. Moreover, S-NP exposure inhibited the expression of the CREB-dependent LTAM genes nid-1, ptr-15, and unc-86. Our findings provide new insights into long-term S-NP exposure and the impairment of STAM and LTAM, which involve the highly conserved iGluRs and CRH-1/CREB signaling pathways.

Recent Advances in Computer-Aided Structure-Based Drug Design on Ion Channels

Ion channels play important roles in fundamental biological processes, such as electric signaling in cells, muscle contraction, hormone secretion, and regulation of the immune response. Targeting ion channels with drugs represents a treatment option for neurological and cardiovascular diseases, muscular degradation disorders, and pathologies related to disturbed pain sensation. While there are more than 300 different ion channels in the human organism, drugs have been developed only for some of them and currently available drugs lack selectivity. Computational approaches are an indispensable tool for drug discovery and can speed up, especially, the early development stages of lead identification and optimization. The number of molecular structures of ion channels has considerably increased over the last ten years, providing new opportunities for structure-based drug development. This review summarizes important knowledge about ion channel classification, structure, mechanisms, and pathology with the main focus on recent developments in the field of computer-aided, structure-based drug design on ion channels. We highlight studies that link structural data with modeling and chemoinformatic approaches for the identification and characterization of new molecules targeting ion channels. These approaches hold great potential to advance research on ion channel drugs in the future.

Oleanolic acid suppresses pentylenetetrazole-induced seizure in vivo

The aim of this study was to investigate the protective effects of triterpene oleanolic acid on the brain tissue of mice with pentylenetetrazole (PTZ)-induced epileptic seizures. Male Swiss albino mice were randomly separated into five groups as the PTZ, control, and oleanolic acid (10, 30, and 100 mg/kg) groups. PTZ injection was seen to cause significant seizures compared with the control group. Oleanolic acid significantly prolonged the latency to onset of myoclonic jerks and the duration of clonic convulsions, and decreased mean seizure scores following PTZ administration. Pretreatment with oleanolic acid also led to an increase in antioxidant enzyme activity (CAT and AChE) and levels (GSH and SOD) in the brain. The data obtained from this study support oleanolic acid may have anticonvulsant potential in PTZ-induced seizures, prevent oxidative stress and protect against cognitive disturbances. These results may provide useful information for the inclusion of oleanolic acid in epilepsy treatment.

Sigma-1 receptor and seizures

Over the last decade, sigma-1 receptor (Sig1R) has been recognized as a valid target for the treatment of seizure disorders and seizure-related comorbidities. Clinical trials with Sig1R ligands are underway testing therapies for the treatment of drug-resistant seizures, developmental and epileptic encephalopathies, and photosensitive epilepsy. However, the direct molecular mechanism by which Sig1R modulates seizures and the balance between excitatory and inhibitory pathways has not been fully elucidated. This review article aims to summarize existing knowledge of Sig1R and its involvement in seizures by focusing on the evidence obtained from Sig1R knockout animals and the anti-seizure effects of Sig1R ligands. In addition, this review article includes a discussion of the advantages and disadvantages of the use of existing compounds and describes the challenges and future perspectives on the use of Sig1R as a target for the treatment of seizure disorders.

Glutamatergic neurotransmission: A potential pharmacotherapeutic target for the treatment of cognitive disorders

In the mammalian brain, glutamate is regarded to be the primary excitatory neurotransmitter due to its widespread distribution and wide range of metabolic functions. Glutamate plays key roles in regulating neurogenesis, synaptogenesis, neurite outgrowth, and neuron survival in the brain. Ionotropic and metabotropic glutamate receptors, neurotransmitters, neurotensin, neurosteroids, and others co-ordinately formulate a complex glutamatergic network in the brain that maintains optimal excitatory neurotransmission. Cognitive activities are potentially synchronized by the glutamatergic activities in the brain via restoring synaptic plasticity. Dysfunctional glutamate receptors and other glutamatergic components are responsible for the aberrant glutamatergic activity in the brain that cause cognitive impairments, loss of synaptic plasticity, and neuronal damage. Thus, controlling the brain's glutamatergic transmission and modifying glutamate receptor function could be a potential therapeutic strategy for cognitive disorders. Certain drugs that regulate glutamate receptor activities have shown therapeutic promise in improving cognitive functions in preclinical and clinical studies. However, several issues regarding precise functional information of glutamatergic activity are yet to be comprehensively understood. The present article discusses the scope of developing glutamatergic systems as prospective pharmacotherapeutic targets to treat cognitive disorders. Special attention has been given to recent developments, challenges, and future prospects.

Role of long noncoding RNAs; BDNF-AS and 17A and their relation to GABAergic dysfunction in Egyptian epileptic patients

Epilepsy is a chronic neurological disorder characterized by recurrent unprovoked seizures. Lately, long noncoding RNAs (lncRNAs) have been increasingly appreciated as regulators of epilepsy-related processes, however, their functional role in its pathogenesis is still to be explored. This study investigated the expression levels of lncRNAs; BDNF-AS and 17A in the sera of Egyptian patients with idiopathic generalized and symptomatic focal epilepsy and correlated their levels with brain-derived neurotrophic factor (BDNF), phosphorylated cAMP reaction element -binding protein (p-CREB), gamma- aminobutyric acid (GABA) and glutamate, to underline their related molecular mechanism. A total of 70 epileptic patients were divided into two clinical types, besides 30 healthy controls of matched age and sex. The expression levels of both lncRNAs were markedly upregulated in epileptic groups versus the healthy control group with predominance in the symptomatic focal one. Epileptic patients showed significantly lower levels of BDNF, p-CREB, GABA along with significant increase of glutamate levels and glutamate/ GABA ratio, especially in symptomatic focal versus idiopathic generalized epileptic ones. The obtained data raised the possibility that these lncRNAs might be involved in the pathogenesis of epilepsy via inhibition of GABA/p-CREB/BDNF pathway. The study shed light on the putative role of these lncRNAs in better diagnosis of epilepsy, particularly symptomatic focal epilepsy.

Antitumor Potential of Antiepileptic Drugs in Human Glioblastoma: Pharmacological Targets and Clinical Benefits

Glioblastoma (GBM) is characterized by fast-growing cells, genetic and phenotypic heterogeneity, and radio-chemo-therapy resistance, contributing to its dismal prognosis. Various medical comorbidities are associated with the natural history of GBM. The most disabling and greatly affecting patients' quality of life are neurodegeneration, cognitive impairment, and GBM-related epilepsy (GRE). Hallmarks of GBM include molecular intrinsic mediators and pathways, but emerging evidence supports the key role of non-malignant cells within the tumor microenvironment in GBM aggressive behavior. In this context, hyper-excitability of neurons, mediated by glutamatergic and GABAergic imbalance, contributing to GBM growth strengthens the cancer-nervous system crosstalk. Pathogenic mechanisms, clinical features, and pharmacological management of GRE with antiepileptic drugs (AEDs) and their interactions are poorly explored, yet it is a potentially promising field of research in cancer neuroscience. The present review summarizes emerging cooperative mechanisms in oncogenesis and epileptogenesis, focusing on the neuron-to-glioma interface. The main effects and efficacy of selected AEDs used in the management of GRE are discussed in this paper, as well as their potential beneficial activity as antitumor treatment. Overall, although still many unclear processes overlapping in GBM growth and seizure onset need to be elucidated, this review focuses on the intriguing targeting of GBM-neuron mutual interactions to improve the outcome of the so challenging to treat GBM.

Riluzole and novel naphthalenyl substituted aminothiazole derivatives prevent acute neural excitotoxic injury in a rat model of temporal lobe epilepsy

Epileptogenic seizures, or status epilepticus (SE), leads to excitotoxic injury in hippocampal and limbic neurons in the kainic acid (KA) animal model of temporal lobe epilepsy (TLE). Here, we have further characterized neural activity regulated methylaminoisobutryic acid (MeAIB)/glutamine transport activity in mature rat hippocampal neurons in vitro that is inhibited by riluzole (IC₅₀ = 1 μM), an anti-convulsant benzothiazole agent. We screened a library of riluzole derivatives and identified SKA-41 followed by a second screen and synthesized several novel chlorinated aminothiazoles (SKA-377, SKA-378, SKA-379) that are also potent MeAIB transport inhibitors in vitro, and brain penetrant following systemic administration. When administered before KA, SKA-378 did not prevent seizures but still protected the hippocampus and several other limbic areas against SE-induced neurodegeneration at 3d. When SKA-377 - 379, (30 mg/kg) were administered after KA-induced SE, acute neural injury in the CA3, CA1 and CA4/hilus was also largely attenuated. Riluzole (10 mg/kg) blocks acute neural injury. Kinetic analysis of SKA-378 and riluzoles' blockade of Ca²⁺-regulated MeAIB transport in neurons in vitro indicates that inhibition occurs via a non-competitive, indirect mechanism. Sodium channel Na_V1.6 antagonism blocks neural activity regulated MeAIB/Gln transport in vitro (IC₅₀ = 60 nM) and SKA-378 is the most potent inhibitor of Na_V1.6 (IC₅₀ = 28 μM) compared to Na_V1.2 (IC₅₀ = 118 μM) in heterologous cells. However, pharmacokinetic analysis suggests that sodium channel blockade may not be the predominant mechanism of neuroprotection here. Riluzole and our novel aminothiazoles are agents that attenuate acute neural hippocampal injury following KA-induced SE and may help to understand mechanisms involved in the progression of epileptic disease.

The role of ATP1A3 gene in epilepsy: We need to know more

The ATP1A3 gene, which encodes the Na⁺/K⁺-ATPase α3 catalytic subunit, plays a crucial role in both physiological and pathological conditions in the brain, and mutations in this gene have been associated with a wide variety of neurological diseases by impacting the whole infant development stages. Cumulative clinical evidence suggests that some severe epileptic syndromes have been linked to mutations in ATP1A3, among which inactivating mutation of ATP1A3 has been intriguingly found to be a candidate pathogenesis for complex partial and generalized seizures, proposing ATP1A3 regulators as putative targets for the rational design of antiepileptic therapies. In this review, we introduced the physiological function of ATP1A3 and summarized the findings about ATP1A3 in epileptic conditions from both clinical and laboratory aspects at first. Then, some possible mechanisms of how ATP1A3 mutations result in epilepsy are provided. We think this review timely introduces the potential contribution of ATP1A3 mutations in both the genesis and progression of epilepsy. Taken that both the detailed mechanisms and therapeutic significance of ATP1A3 for epilepsy are not yet fully illustrated, we think that both in-depth mechanisms investigations and systematic intervention experiments targeting ATP1A3 are needed, and by doing so, perhaps a new light can be shed on treating ATP1A3-associated epilepsy.