Synaptic Vesicle Glycoprotein 2A Ligands in the Treatment of Epilepsy and Beyond

CB1R activates the epilepsy-associated protein Go to regulate neurotransmitter release and synaptic plasticity in the cerebellum

GNAO1 encodes the alpha subunit of the heterotrimeric Go protein. Despite being the most abundant G protein at synapses, the role of Go in the brain remains unclear, primarily because of the high mortality associated with developmental and epileptic encephalopathy (DEE) 17 in Gnao1 mutated animals. Here, we conducted proteomic analyses with a brain synaptosomal fraction to investigate the Go-interactome and then generated a non-DEE model using Gli1CreERT2 mice to selectively knockout (KO) the presynaptic Gαo within cerebellum. Our findings revealed that Gαo interacts with multiple proteins involved in neurotransmitter release, as well as cannabinoid receptor type 1 (CB1R), a key Gi/o-coupled receptor in presynaptic terminals. In Gnao1 KO mice, synapse formation was reduced in the cerebellum with a concomitant reduction in depolarization-induced suppression of excitation, a manifestation of CB1R-mediated synaptic plasticity found in the cerebellum. These mice displayed motor deficits in rotarod, grip strength, gait, and beam balance tests. Our results suggest that Go plays a critical role in regulating neurotransmitter releases at the presynaptic terminals and its absence in the entire brain may contribute to DEE pathogenesis. This study also provides valuable insights into the signaling pathways in the brain from a Go-dependent perspective.

Impact of levetiracetam and ethanol on memory, selected neurotransmitter levels, oxidative stress parameters, and essential elements in rats

BACKGROUND

Ethanol disrupts brain activity and memory. There is evidence supporting the beneficial effect of levetiracetam on alcohol consumption. Therefore, the aim of the study was to examine whether levetiracetam has a protective activity against ethanol-induced memory impairment, alterations in selected neurotransmission activities, oxidative stress, and selected essential elements in rats.

METHODS

The rats were given levetiracetam (300 mg/kg b.w. po) with ethanol for three weeks prior to behavioral tests. Spatial memory was tested using the Morris water maze, while recognition memory was evaluated using the Novel object recognition test. The GABA and glutamate concentration was determined in three rat brain regions (cerebellum, hippocampus, and cerebral cortex). Serum oxidative stress parameters and selected essential elements concentration (Cu, Mn, Zn, Fe, Mg) in the rat brain were analyzed.

RESULTS

Levetiracetam administered with ethanol improved spatial memory, but did not affect abstinence-induced impairment. The drug also decreased ethanol-induced long-term recognition memory impairment. No alterations in glutamate levels were observed. GABA levels were elevated by levetiracetam in the cerebral cortex and by ethanol in the cerebellum. Ethanol increased catalase activity (CAT) and decreased superoxide dismutase activity (SOD) in the serum. Levetiracetam significantly increased the activity of SOD. Alcohol disrupted the levels of trace elements (Mn, Zn, Mg) in the rat brain. Additionally, levetiracetam alone increased Mg, Fe, and Cu concentrations while all animals receiving the drug also had significantly lower concentrations of Zn.

CONCLUSIONS

Levetiracetam had differential effects against ethanol-induced impairments. These findings could have important implications for future levetiracetam treatment in patients.

Levetiracetam prevents Aβ42 production through SV2a-dependent modulation of App processing in Alzheimer's disease models

In Alzheimer's disease (AD), amyloid-beta (Aβ) peptides are produced by proteolytic cleavage of the amyloid precursor protein (APP), which can occur during synaptic vesicle (SV) cycling at presynapses. Precisely how amyloidogenic APP processing may impair presynaptic proteostasis and how to therapeutically target this process remains poorly understood. Using App knock-in mouse models of early Aβ pathology, we found proteins with hampered degradation accumulate at presynaptic sites. At this mild pathological stage, amyloidogenic processing leads to accumulation of Aβ42 inside SVs. To explore if targeting SVs modulates Aβ accumulation, we investigated levetiracetam (Lev), a SV-binding small molecule drug that has shown promise in mitigating AD-related pathologies despite its mechanism of action being unclear. We discovered Lev reduces Aβ42 levels by decreasing amyloidogenic processing of APP in a SV2a-dependent manner. Lev corrects SV protein levels and cycling, which results in increased surface localization of APP, where it favors processing via the non-amyloidogenic pathway. Using metabolic stable isotopes and mass spectrometry we confirmed that Lev prevents the production of Aβ42 in vivo. In transgenic mice with aggressive pathology, electrophysiological and immunofluorescent microscopy analyses revealed that Lev treatment reduces SV cycling and minimizes synapse loss. Finally, we found that human Down syndrome brains with early Aβ pathology, have elevated levels of presynaptic proteins, confirming a comparable presynaptic deficit in human brains. Taken together, we report a mechanism that highlights the therapeutic potential of Lev to modify the early stages of AD and represent a promising strategy to prevent Aβ42 pathology before irreversible damage occurs.

Safflower yellow alleviates cognitive impairment in mice by modulating cholinergic system function, oxidative stress, and CREB/BDNF/TrkB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Carthamus tinctorius L. (Safflower) was believed to have multiple benefits, including antioxidant effects, enhanced learning and memory, and improving neuronal injury. Safflower Yellow(SY) are the main active ingredients of Safflower, displays strong pharmacological potential treatment of Alzheimer's disease(AD). However, its effect on memory impairments remains insufficiently investigated.

AIM OF THE STUDY

The study aims to investigate the effects of SY on cognitive functions in memory impairments model and to explore the mechanism of its action.

MATERIALS AND METHODS

We utilized the Morris Water Maze, Step-Through Test, Step-Down Test to assess the potential of SY in ameliorating learning and memory dysfunction caused by SCOP, NaNO2 and ethanol in mice. Bioinformatic analysis and molecular biological approaches were used to study the related mechanisms of SY on anti-memory impairments.

RESULTS

The results of the Morris Water Test suggested that SY could shorten the escape latency and the time of the first crossing platform in the mice with memory acquisition and memory consolidation impairments, and increase the platform crossing times. The results of the Step-Though test and Step-Down test showed that the escape latency in the mice was prolonged and the number of errors was reduced after SY treatment. ELISA experiments indicated that SY decreased the AChE activities, increased the ChAT activities, and modulated oxidative stress markers (SOD, MDA, and GSH-PX) in scopolamine-induced mice. Western Blot and Nissl staining showed that SY could activated BDNF/TrkB/CREB signaling pathway and reduced neuronal damage.

CONCLUSION

The findings present that SY can restore the function of the cholinergic system, inhibit oxidative stress, regulate the expression of upstream and downstream proteins in the CREB/BDNF/TrkB pathway, and alleviate brain tissue damage to improve memory impairment in mice.

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.

Developing Low Molecular Weight PET and SPECT Imaging Agents

Imaging agents for positron emission tomography (PET) and single-photon emission computerized tomography (SPECT) have shown their utility in many situations, answering clinical questions related to drug development and medical considerations. The discovery and development of imaging agents follow a well-understood process, with variations related to available starting points and to the envisaged imaging application. This article describes the general development path leading from the expression of an imaging need and project initiation to a clinically usable imaging agent. The definition of the project rationale, the design and optimization of early leads, and the assessment of the imaging potential of an imaging agent candidate are followed by preclinical and clinical development activities that differ from those required for therapeutic agents. These include radiolabeling with a positron emitter and first-in-human clinical studies, to rapidly evaluate the ability of a new imaging agent to address the questions it was designed to answer.

Narrative Review of Brivaracetam: Preclinical Profile and Clinical Benefits in the Treatment of Patients with Epilepsy

One third of patients with epilepsy will continue to have uncontrolled seizures despite treatment with antiseizure medications (ASMs). There is therefore a need to develop novel ASMs. Brivaracetam (BRV) is an ASM that was developed in a major drug discovery program aimed at identifying selective, high-affinity synaptic vesicle protein 2A (SV2A) ligands, the target molecule of levetiracetam. BRV binds to SV2A with 15- to 30-fold higher affinity and greater selectivity than levetiracetam. BRV has broad-spectrum antiseizure activity in animal models of epilepsy, a favorable pharmacokinetic profile, few clinically relevant drug-drug interactions, and rapid brain penetration. BRV is available in oral and intravenous formulations and can be initiated at target dose without titration. Efficacy and safety of adjunctive BRV (50-200 mg/day) treatment of focal-onset seizures was demonstrated in three pivotal phase III trials (NCT00490035/NCT00464269/NCT01261325), including in patients who had previously failed levetiracetam. Efficacy and safety of adjunctive BRV were also demonstrated in adult Asian patients with focal-onset seizures (NCT03083665). In several open-label trials (NCT00150800/NCT00175916/NCT01339559), long-term safety and tolerability of adjunctive BRV was established, with efficacy maintained for up to 14 years, with high retention rates. Evidence from daily clinical practice highlights BRV effectiveness and tolerability in specific epilepsy patient populations with high unmet needs: the elderly (≥ 65 years of age), children (< 16 years of age), patients with cognitive impairment, patients with psychiatric comorbid conditions, and patients with acquired epilepsy of specific etiologies (post-stroke epilepsy/brain tumor related epilepsy/traumatic brain injury-related epilepsy). Here, we review the preclinical profile and clinical benefits of BRV from pivotal trials and recently published evidence from daily clinical practice.

Development of SV2A Ligands for Epilepsy Treatment: A Review of Levetiracetam, Brivaracetam, and Padsevonil

Epilepsy is a common neurological disorder that is primarily treated with antiseizure medications (ASMs). Although dozens of ASMs are available in the clinic, approximately 30% of epileptic patients have medically refractory seizures; other limitations in most traditional ASMs include poor tolerability and drug-drug interactions. Therefore, there is an urgent need to develop alternative ASMs. Levetiracetam (LEV) is a first-line ASM that is well tolerated, has promising efficacy, and has little drug-drug interaction. Although it is widely accepted that LEV acts through a unique therapeutic target synaptic vesicle protein (SV) 2A, the molecular basis of its action remains unknown. Even so, the next-generation SV2A ligands against epilepsy based on the structure of LEV have achieved clinical success. This review highlights the research and development (R&D) process of LEV and its analogs, brivaracetam and padsevonil, to provide ideas and experience for the R&D of novel ASMs.

Lycium Barbarum Polysaccharides Improves Cognitive Functions in ICV-STZ-Induced Alzheimer's Disease Mice Model by Improving the Synaptic Structural Plasticity and Regulating IRS1/PI3K/AKT Signaling Pathway

Lycium barbarum polysaccharide (LBP) have a certain curative effect on hypoglycemic and neuroprotective effects, but the specific mechanism is unclear and needs to be further explored. This study aimed to clarify the mechanisms of LBP in the treatment of ICV-STZ mice model of AD from the perspectives of insulin resistance, IRS1/PI3K/AKT signaling pathway, and synaptic protein expression. We used male C57BL/6J mice injected with STZ (3 mg/kg) in the lateral ventricle as an AD model. After treatment with LBP, the learning and memory abilities of ICV-STZ mice were enhanced, and the pathological changes in brain tissue were alleviated. LBP can regulate the expression of proteins related to the IRS1/PI3K/AKT signaling pathway and thereby reducing Aβ deposition and tau protein phosphorylation in the brain of ICV-STZ mice. In addition, LBP also can up-regulate the expression of synaptic proteins. The results indicated that LBP played a neuroprotective role by regulating the IRS1/PI3K/AKT pathway, inhibiting tau protein hyperphosphorylation and improving the expression levels of synapse-related proteins.

Modulation of hippocampal activity in schizophrenia with levetiracetam: a randomized, double-blind, cross-over, placebo-controlled trial

Hippocampal hyperactivity is a novel pharmacological target in the treatment of schizophrenia. We hypothesized that levetiracetam (LEV), a drug binding to the synaptic vesicle glycoprotein 2 A, normalizes hippocampal activity in persons with schizophrenia and can be measured using neuroimaging methods. Thirty healthy control participants and 30 patients with schizophrenia (28 treated with antipsychotic drugs), were randomly assigned to a double-blind, cross-over trial to receive a single administration of 500 mg oral LEV or placebo during two study visits. At each visit, we assessed hippocampal function using resting state fractional amplitude of low frequency fluctuations (fALFF), cerebral blood flow (CBF) with arterial spin labeling, and hippocampal blood-oxygen-level-dependent (BOLD) signal during a scene processing task. After placebo treatment, we found significant elevations in hippocampal fALFF in patients with schizophrenia, consistent with hippocampal hyperactivity. Additionally, hippocampal fALFF in patients with schizophrenia after LEV treatment did not significantly differ from healthy control participants receiving placebo, suggesting that LEV may normalize hippocampal hyperactivity. In contrast to our fALFF findings, we did not detect significant group differences or an effect of LEV treatment on hippocampal CBF. In the context of no significant group difference in BOLD signal, we found that hippocampal recruitment during scene processing is enhanced by LEV more significantly in schizophrenia. We conclude that pharmacological modulation of hippocampal hyperactivity in schizophrenia can be studied with some neuroimaging methods, but not others. Additional studies in different cohorts, employing alternate neuroimaging methods and study designs, are needed to establish levetiracetam as a treatment for schizophrenia.

Epilepsy and epileptiform activity in late-onset Alzheimer disease: clinical and pathophysiological advances, gaps and conundrums

A growing body of evidence has demonstrated a link between Alzheimer disease (AD) and epilepsy. Late-onset epilepsy and epileptiform activity can precede cognitive deterioration in AD by years, and its presence has been shown to predict a faster disease course. In animal models of AD, amyloid and tau pathology are linked to cortical network hyperexcitability that precedes the first signs of memory decline. Thus, detection of epileptiform activity in AD has substantial clinical importance as a potential novel modifiable risk factor for dementia. In this Review, we summarize the epidemiological evidence for the complex bidirectional relationship between AD and epilepsy, examine the effect of epileptiform activity and seizures on cognition in people with AD, and discuss the precision medicine treatment strategies based on the latest research in human and animal models. Finally, we outline some of the unresolved questions of the field that should be addressed by rigorous research, including whether particular clinicopathological subtypes of AD have a stronger association with epilepsy, and the sequence of events between epileptiform activity and amyloid and tau pathology.

Advancements in the study of synaptic plasticity and mitochondrial autophagy relationship

Synapses serve as the points of communication between neurons, consisting primarily of three components: the presynaptic membrane, synaptic cleft, and postsynaptic membrane. They transmit signals through the release and reception of neurotransmitters. Synaptic plasticity, the ability of synapses to undergo structural and functional changes, is influenced by proteins such as growth-associated proteins, synaptic vesicle proteins, postsynaptic density proteins, and neurotrophic growth factors. Furthermore, maintaining synaptic plasticity consumes more than half of the brain's energy, with a significant portion of this energy originating from ATP generated through mitochondrial energy metabolism. Consequently, the quantity, distribution, transport, and function of mitochondria impact the stability of brain energy metabolism, thereby participating in the regulation of fundamental processes in synaptic plasticity, including neuronal differentiation, neurite outgrowth, synapse formation, and neurotransmitter release. This article provides a comprehensive overview of the proteins associated with presynaptic plasticity, postsynaptic plasticity, and common factors between the two, as well as the relationship between mitochondrial energy metabolism and synaptic plasticity.

Changes in the Dentate Gyrus Gene Expression Profile Induced by Levetiracetam Treatment in Rats with Mesial Temporal Lobe Epilepsy

Temporal lobe epilepsy (TLE) is one of the most common forms of focal epilepsy. Levetiracetam (LEV) is an antiepileptic drug whose mechanism of action at the genetic level has not been fully described. Therefore, the aim of the present work was to evaluate the relevant gene expression changes in the dentate gyrus (DG) of LEV-treated rats with pilocarpine-induced TLE. Whole-transcriptome microarrays were used to obtain the differential genetic profiles of control (CTRL), epileptic (EPI), and EPI rats treated for one week with LEV (EPI + LEV). Quantitative RT-qPCR was used to evaluate the RNA levels of the genes of interest. According to the results of the EPI vs. CTRL analysis, 685 genes were differentially expressed, 355 of which were underexpressed and 330 of which were overexpressed. According to the analysis of the EPI + LEV vs. EPI groups, 675 genes were differentially expressed, 477 of which were downregulated and 198 of which were upregulated. A total of 94 genes whose expression was altered by epilepsy and modified by LEV were identified. The RT-qPCR confirmed that LEV treatment reversed the increased expression of Hgf mRNA and decreased the expression of the Efcab1, Adam8, Slc24a1, and Serpinb1a genes in the DG. These results indicate that LEV could be involved in nonclassical mechanisms involved in Ca2+ homeostasis and the regulation of the mTOR pathway through Efcab1, Hgf, SLC24a1, Adam8, and Serpinb1a, contributing to reduced hyperexcitability in TLE patients.

Anti-seizure effects of JNJ-54175446 in the intra-amygdala kainic acid model of drug-resistant temporal lobe epilepsy in mice

There remains a need for new drug targets for treatment-resistant temporal lobe epilepsy. The ATP-gated P2X7 receptor coordinates neuroinflammatory responses to tissue injury. Previous studies in mice reported that the P2X7 receptor antagonist JNJ-47965567 suppressed spontaneous seizures in the intraamygdala kainic acid model of epilepsy and reduced attendant gliosis in the hippocampus. The drug-resistance profile of this model is not fully characterised, however, and newer P2X7 receptor antagonists with superior pharmacokinetic profiles have recently entered clinical trials. Using telemetry-based continuous EEG recordings in mice, we demonstrate that spontaneous recurrent seizures in the intraamygdala kainic acid model are refractory to the common anti-seizure medicine levetiracetam. In contrast, once-daily dosing of JNJ-54175446 (30 mg/kg, intraperitoneal) resulted in a significant reduction in spontaneous recurrent seizures which lasted several days after the end of drug administration. Using a combination of immunohistochemistry and ex vivo radiotracer assay, we find that JNJ-54175446-treated mice at the end of recordings display a reduction in astrogliosis and altered microglia process morphology within the ipsilateral CA3 subfield of the hippocampus, but no difference in P2X7 receptor surface expression. The present study extends the characterisation of the drug-resistance profile of the intraamygdala kainic acid model in mice and provides further evidence that targeting the P2X7 receptor may have therapeutic applications in the treatment of temporal lobe epilepsy.

Serum MicroRNAs as Predictors of Diagnosis and Drug-resistance in Temporal Lobe Epilepsy: A Preliminary Study

OBJECTIVE

Temporal lobe epilepsy (TLE) is the most common form of refractory focal epilepsy, and the current clinical diagnosis is based on EEG, clinical neurological history and neuroimaging findings.

METHODS

So far, there are no blood-based molecular biomarkers of TLE to support clinical diagnosis, despite the pathogenic mechanisms underlying TLE involving defects in the regulation of gene expression. MicroRNAs (miRNAs) have emerged as important post-transcriptional regulators of gene expression.

RESULTS

Recent studies show the feasibility of detecting miRNAs in body fluids; circulating miRNAs have emerged as potential clinical biomarkers in epilepsy, although the TLE miRNA profile needs to be addressed. Here, we analysed the diagnostic potential of 8 circulating miRNAs in sera of 52 TLE patients and 40 age- and sex-matched donor controls by RT-qPCR analyses.

CONCLUSION

We found that miR-34a-5p, -106b-5p, -130a-3p, -146a-5p, and -19a-3p are differently expressed in TLE compared to control subjects, suggesting a diagnostic role. Furthermore, we found that miR-34a-5p, -106b-5p, -146a-5p and miR-451a could become prognostic biomarkers, being differentially expressed between drug-resistant and drug-responsive TLE subjects. Therefore, serum miRNAs are diagnostic and drug-resistance predictive molecules of TLE.

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.

Assessment of Biochemical and Neuroactivities of Cultural Filtrate from Trichoderma harzianum in Adjusting Electrolytes and Neurotransmitters in Hippocampus of Epileptic Rats

BACKGROUND

Epilepsy is a serious chronic neurological disorder, which is accompanied by recurrent seizures. Repeated seizures cause physical injuries and neuronal dysfunction and may be a risk of cancer and vascular diseases. However, many antiepileptic drugs (AEDs) have side effects of mood alteration or neurocognitive function, a reduction in neuron excitation, and the inhibition of normal activity. Therefore, the present study aimed to evaluate the effect of secondary metabolites of Trichoderma harzianum cultural filtrate (ThCF) when adjusting different electrolytes and neurotransmitters in the hippocampus of epileptic rats.

METHODS

Cytotoxicity of ThCF against LS-174T cancer cells was assessed using a sulforhodamine B (SRB) assay. Quantitative estimation for some neurotransmitters, electrolytes in sera or homogenate of hippocampi tissues, and mRNA gene expression for ion or voltage gates was assessed by quantitative Real-Time PCR.

RESULTS

Treatment with ThCF reduces the proliferative percentage of LS-174T cells in a concentration-dependent manner. ThCF administration improves hyponatremia, hyperkalemia, and hypocalcemia in the sera of the epilepticus model. ThCF rebalances the elevated levels of many neurotransmitters and reduces the release of GABA and acetylcholine-esterase. Also, treatments with ThCF ameliorate the downregulation of mRNA gene expression for some gate receptors in hippocampal homogenate tissues and recorded a highly significant elevation in the expression of SCN1A, CACNA1S, and NMDA.

CONCLUSION

Secondary metabolites of Trichoderma (ThCF) have cytotoxic activity against LS-174T (colorectal cancer cell line) and anxiolytic-like activity through a GABAergic mechanism of action and an increase in GABA as inhibitory amino acid in the selected brain regions and reduced levels of NMDA and DOPA. The present data suggested that ThCF may inhibit intracellular calcium accumulation by triggering the NAADP-mediated Ca2+ signaling pathway. Therefore, the present results suggested further studies on the molecular pathway for each metabolite of ThCF, e.g., 6-pentyl-α-pyrone (6-PP), harzianic acid (HA), and hydrophobin, as an alternative drug to mitigate the side effects of AEDs.

Levetiracetam and Midazolam vs Midazolam Alone for First-Line Treatment of Children With Generalized Convulsive Status Epilepticus (Lev-Mid Study): A Randomized Controlled Trial

BACKGROUND

Benzodiazepines are the first-line anti-seizure medication (ASM) for generalized convulsive status epilepticus (GCSE), but they fail to end seizures in a third of cases. Combining benzodiazepines with another ASM that acts by a different pathway could be a potential strategy for rapid control of GCSE.

OBJECTIVES

To evaluate the efficacy of adding levetiracetam to midazolam in the initial treatment of pediatric GCSE.

DESIGN

Double-blind randomized controlled trial.

SETTING

Pediatric emergency room at Sohag University Hospital between June, 2021 and August, 2022.

PARTICIPANTS

Children aged between 1 month and 16 years with GCSE lasting more than 5 min.

INTERVENTIONS

Intravenous levetiracetam (60 mg/kg over 5 min) and midazolam (Lev-Mid group) or placebo and midazolam (Pla-Mid group) as first-line anticonvulsive therapy.

OUTCOME MEASURES

Primary: cessation of clinical seizures at 20-min study time point. Secondary: cessation of clinical seizures at 40-min study time point, need for a second midazolam dose, seizure control at 24-hr, need for intubation, and adverse effects.

RESULTS

Cessation of clinical seizures at 20-min occurred in 55 children (76%) in Lev-Mid group compared with 50 (69%) in the Pla-Mid group [RR (95% CI) 1.1 (0.9-1.34); P=0.35]. No significant difference was found between the two groups regarding the need for a second midazolam dose [44.4% vs 55.6%; RR (95% CI) 0.8 (0.58-1.11); P=0.18] as well as cessation of clinical seizures at 40-min [96% vs 92%; RR (95% CI)1.05 (0.96-1.14); P=0.49] and seizure control at 24-hr [85% vs 76%; RR (95% CI) 1.12 (0.94-1.3); P=0.21]. Intubation was required for three patients in the Lev-Mid group and six patients in the Pla-Mid group [RR (95%CI) 0.5 (0.13- 1.92); P=0.49]. No other adverse effects or mortality were observed during the 24-hour study timeframe.

CONCLUSION

Combined levetiracetam and midazolam for initial management of pediatric GCSE presents no significant advantage over midazolam alone in cessation of clinical seizures at 20-min.

Animal Models of Drug-Resistant Epilepsy as Tools for Deciphering the Cellular and Molecular Mechanisms of Pharmacoresistance and Discovering More Effective Treatments

In the last 30 years, over 20 new anti-seizure medicines (ASMs) have been introduced into the market for the treatment of epilepsy using well-established preclinical seizure and epilepsy models. Despite this success, approximately 20-30% of patients with epilepsy have drug-resistant epilepsy (DRE). The current approach to ASM discovery for DRE relies largely on drug testing in various preclinical model systems that display varying degrees of ASM drug resistance. In recent years, attempts have been made to include more etiologically relevant models in the preclinical evaluation of a new investigational drug. Such models have played an important role in advancing a greater understanding of DRE at a mechanistic level and for hypothesis testing as new experimental evidence becomes available. This review provides a critical discussion of the pharmacology of models of adult focal epilepsy that allow for the selection of ASM responders and nonresponders and those models that display a pharmacoresistance per se to two or more ASMs. In addition, the pharmacology of animal models of major genetic epilepsies is discussed. Importantly, in addition to testing chemical compounds, several of the models discussed here can be used to evaluate other potential therapies for epilepsy such as neurostimulation, dietary treatments, gene therapy, or cell transplantation. This review also discusses the challenges associated with identifying novel therapies in the absence of a greater understanding of the mechanisms that contribute to DRE. Finally, this review discusses the lessons learned from the profile of the recently approved highly efficacious and broad-spectrum ASM cenobamate.

A review of cognitive and behavioral outcomes of Brivaracetam

Anti-seizure medications (ASMs) can cause cognitive or behavioral adverse drug reactions, which is an important consideration when selecting an appropriate ASM. Brivaracetam (BRV) is a newer synaptic vesicle protein 2A ligand, which is expected to result in fewer neuropsychiatric adverse effects due to its mechanism of action. To understand the impact of BRV on cognition and behavior compared with other ASMs, we conducted a review of the literature using the Cochrane Library, PubMed/MEDLINE, and Embase. After the screening process, a total of two animal studies, one randomized controlled trial, one pooled analysis of clinical trials, one controlled study, and nine observational studies were included. The animal studies showed that BRV did not worsen cognitive or behavioral performance in rodents. The human studies showed that BRV was associated with fewer cognitive adverse events compared with other second- or third-generation ASMs. In addition, BRV was less associated with behavioral disturbance than levetiracetam. In summary, this review revealed that BRV has a limited impact on cognition and behavior. For patients who are intolerant to levetiracetam and have levetiracetam-related behavioral side effects, switching to BRV could be beneficial. However, heterogeneity between studies resulted in low-quality of evidence, and further trials are needed to confirm the findings.

SDI-118, a novel procognitive SV2A modulator: First-in-human randomized controlled trial including PET/fMRI assessment of target engagement

Background: Current treatments for progressive neurodegenerative disorders characterized by cognitive impairment either have limited efficacy or are lacking altogether. SDI-118 is a small molecule which modulates the activity of synaptic vesicle glycoprotein 2A (SV2A) in the brain and shows cognitive enhancing effects in a range of animal models of cognitive deficit. Methods: This first-in-human study evaluated safety, tolerability, and pharmacokinetics/pharmacodynamics of SDI-118 in single ascending oral doses up to 80 mg administered to 32 healthy male subjects. Brain target occupancy was measured in eight subjects using positron emission tomography with PET-ligand [¹¹C]-UCB-J. Food effect was assessed in seven subjects. Mood state was regularly evaluated using standardized questionnaires, and resting state fMRI data were analyzed as exploratory objectives. Key Results: At all doses tested, SDI-118 was well tolerated and appeared safe. Adverse events were mainly dizziness, hypersomnia, and somnolence. All were mild in intensity and increased in frequency with increasing administered dose. No dose-limiting adverse reactions were observed at any dose. SDI-118 displayed a linear pharmacokinetic profile with no significant food effect. Brain penetration and target engagement were demonstrated by a dose-proportional SV2A occupancy. Conclusion: Single oral doses of SDI-118 up to 80 mg were very well tolerated in healthy male subjects. Dose-proportional SV2A occupancy in the brain was demonstrated with brain imaging. Adverse effects in humans mainly occurred in higher dose ranges, with high occupancy levels, and were all mild and self-limiting. These data support further clinical exploration of the compound in patients with cognitive disorders. Clinical Trial Registration: https://clinicaltrials.gov/, identifier NCT05486195.

Levetiracetam Attenuates Adolescent Stress-induced Behavioral and Electrophysiological Changes Associated With Schizophrenia in Adult Rats

BACKGROUND AND HYPOTHESIS

Stress during adolescence is a major risk factor for schizophrenia. We have found previously in rats that adolescent stress caused, in adulthood, behavioral changes and enhanced ventral tegmental area (VTA) dopamine system activity, which were associated with dysregulation of the excitatory-inhibitory (E/I) balance in the ventral hippocampus (vHip). Levetiracetam, an anticonvulsant drug, regulates the release of neurotransmitters, including glutamate, via SV2A inhibition. It also modulates parvalbumin interneuron activity via Kv3.1 channels. Therefore, levetiracetam could ameliorate deficits in the E/I balance. We tested whether levetiracetam attenuate the adolescent stress-induced behavioral changes, vHip hyperactivity, and enhanced VTA dopamine system activity in adult rats.

STUDY DESIGN

Male Sprague-Dawley rats were subjected to a combination of daily footshock (postnatal day [PD] 31-40), and three 1 h-restraint stress sessions (at PD31, 32, and 40). In adulthood (PD62), animals were tested for anxiety responses (elevated plus-maze and light-dark box), social interaction, and cognitive function (novel object recognition test). The activity of vHip pyramidal neurons and VTA dopamine neurons was also recorded.

STUDY RESULTS

Adolescent stress produced anxiety-like responses and impaired sociability and cognitive function. Levetiracetam (10 mg/kg) reversed these changes. Levetiracetam also reversed the increased VTA dopamine neuron population activity and the enhanced firing rate of vHip pyramidal neurons induced by adolescent stress.

CONCLUSIONS

These findings suggest that levetiracetam attenuates the adverse outcomes associated with schizophrenia caused by stress during adolescence.

BRIVEST: A 'real-world' observational, single-centre study investigating the efficacy, safety and tolerability of Brivaracetam

OBJECTIVE

Via measures of efficacy, tolerability, and safety, this open-label, single-center study assessed the overall effectiveness of Brivaracetam (BRV) for the treatment of epilepsy in the context of 'real-world' clinical practice.

METHODS

Unselected consecutive patients were recruited and stratified into 3 cohorts with either fully prospective, fully retrospective or mixed data collection, dependent on whether their BRV prescriptions were historical, current, or pending. Prospective data were obtained at baseline, 3 and 6 months, and at 6-month intervals thereafter, from patient interviews and seizure diaries, and retrospective data from medical records. Efficacy variables were derived from seizure-related changes, and tolerability and safety variables from reported treatment-emergent adverse events (TEAEs), BRV withdrawal, and changes to questionnaire scores. Additionally, we investigated treatment outcomes for those with previous levetiracetam (LEV) use, a history of psychiatric comorbidity, a learning disability, and of older age.

RESULTS

One hundred and nine patients (58.7% female, mean age 42 years, range: 18 to 72) were included, 59 with prospective follow-up for a minimum of 6 (47 patients, excluding those who withdrew) and a maximum of 24 months (2 patients). Of the full cohort, 87.2% had drug-resistant epilepsy. Retention: At the study end, the median treatment duration was 384 days (range: 6 to 1514 days), and BRV retention was 68.8%. Kaplan-Meier survival functions predicted retention rates of 74.0% and 70.0% at 6 and 12 months respectively.

EFFICACY

At the last follow-up, there was a ≥ 50% responder rate of 30.8%, with 12.1% seizure-free. Seizure frequency categories improved in 31.4% of patients, remained the same in 44.2%, and worsened in 24.4%. Monthly tonic-clonic seizure frequency had significantly decreased, and of those reporting these seizures, 58.3% showed reductions and 25.0% showed complete tonic-clonic seizure freedom.

TOLERABILITY

91.7% of patients reported at least 1 TEAE, with fatigue (30.3%), irritability (29.4%), and depression/low mood (28.4%) as the most common. Only 58.4% of all TEAEs were persistent. Brivaracetam discontinuation due to side effects occurred in 27.5% of the cohort. Depression and anxiety scores remained stable over time, and quality-of-life scores improved. Subgroups: Measures of BRV efficacy and tolerability did not differ according to previous LEV exposure. Tolerability profiles of those with learning disabilities, histories of psychiatric comorbidities, and older age did not greatly differ from the rest of the cohort. Of note, specific history of depression predicted the reporting of suicidal ideation.

CONCLUSION

The BRIVEST study provides real-world evidence of the effectiveness of BRV, suggesting that neither drug-resistant epilepsy nor previous LEV failure should preclude its use. Furthermore, BRV appears to be well-tolerated, even among those from vulnerable patient populations.

Potential risk of liver injury in epileptic patients during COVID-19 pandemic

Most of the antiseizure medications (ASMs) are metabolized in liver and many of them particularly first-generation ASMs have the potential to increase liver enzymes or induce liver injury. Hence, treatment of new onset seizures or epilepsy by ASMs during the course of coronavirus disease 2019 (COVID-19), which could potentially be complicated by hepatic dysfunction, is a challenging clinical issue. Intravenous form of levetiracetam which has no significant hepatic metabolism or drug-drug interaction is often a favorable option to control seizures in acute phase of COVID-19. Administration of enzyme inducer ASMs and valproate with the well-known hepatotoxicity and common drug interactions is not generally recommended. In patients with epilepsy who are under control with potentially hepatotoxic ASMs, close observation and cautious dose reduction or drug switch should be considered if any evidence of hepatic impairment exists. However, risks of possible breakthrough seizures should be weighed against benefits of lowering the hazard of liver injury. In patients with epilepsy who receive polytherapy with ASMs, transient dose modification with the tendency to increase the dose of ASMs with more favorable safety profile and less drug interaction and decrease the dose of drugs with main hepatic metabolism, high protein binding, potential to cause liver injury and known drug-drug reaction should be considered. Finally, decision making should be individualized based on patients' conditions and course of illness.

Rodent Models of Audiogenic Epilepsy: Genetic Aspects, Advantages, Current Problems and Perspectives

Animal models of epilepsy are of great importance in epileptology. They are used to study the mechanisms of epileptogenesis, and search for new genes and regulatory pathways involved in the development of epilepsy as well as screening new antiepileptic drugs. Today, many methods of modeling epilepsy in animals are used, including electroconvulsive, pharmacological in intact animals, and genetic, with the predisposition for spontaneous or refractory epileptic seizures. Due to the simplicity of manipulation and universality, genetic models of audiogenic epilepsy in rodents stand out among this diversity. We tried to combine data on the genetics of audiogenic epilepsy in rodents, the relevance of various models of audiogenic epilepsy to certain epileptic syndromes in humans, and the advantages of using of rodent strains predisposed to audiogenic epilepsy in current epileptology.

Irritability and its relationship with psychosocial symptoms and quality of life in adolescents with epilepsy receiving levetiracetam therapy: A case-control study

BACKGROUND

Levetiracetam, a widely used anticonvulsant drug in children and adolescents, has been associated with irritability, psychosocial symptoms, and low quality of life, which are also influenced by other epilepsy variables.

PURPOSE

The objective of this study was to investigate the level of treatment-related irritability in adolescents receiving levetiracetam, and to evaluate the relationship between irritability levels and psychosocial symptoms, and quality of life.

METHODS

A cross-sectional, case-control study was conducted. Consecutive adolescent patients with epilepsy aged 11-17 years with partial or generalized seizures, treated with either levetiracetam or valproic acid for at least 6 months, and healthy controls were recruited. The Affective Reactivity Index parent report and self-report, Strengths and Difficulties Questionnaire, and Pediatric Quality of Life Inventory-Psychosocial subscale were utilized to assess irritability, psychosocial symptoms, and functioning.

RESULTS

A total of 120 participants were analyzed; 33 patients in the LEV group, 45 patients in the VPA group, and 42 healthy controls. Both self and parent report irritability levels of the LEV group were found to be significantly higher than those of healthy controls. The irritability levels of the LEV and VPA groups were not statistically different, but still the LEV group had higher irritability levels on both scales. In the LEV group, irritability was positively correlated with behavioral, emotional, and attention/hyperactivity problems, and also negatively correlated with psychosocial quality of life.

CONCLUSION

Adolescents with epilepsy using LEV have a high level of irritability and this is associated with some psychosocial symptoms and poor quality of life.

Pharmacological perspectives and mechanisms involved in epileptogenesis

Background

Epileptogenesis can be defined as the process by which a previously healthy brain develops a tendency toward recurrent electrical activity, occurring in three phases: first as an initial trigger (such as stroke, infections, and traumatic brain injury); followed by the latency period and the onset of spontaneous and recurrent seizures which characterizes epilepsy.

Main body

The mechanisms that may be involved in epileptogenesis are inflammation, neurogenesis, migration of neurons to different regions of the brain, neural reorganization, and neuroplasticity.In recent years, experimental studies have enabled the discovery of several mechanisms involved in the process of epileptogenesis, mainly neuroinflammation, that involves the activation of glial cells and an increase in specific inflammatory mediators. The lack of an experimental animal model protocol for epileptogenic compounds contributes to the difficulty in understanding disease development and the creation of new drugs.

Conclusion

To solve these difficulties, a new approach is needed in the development of new AEDs that focus on the process of epileptogenesis and the consolidation of animal models for studies of antiepileptogenic compounds, aiming to reach the clinical phases of the study. Some examples of these compounds are rapamycin, which inhibits mTOR signaling, and losartan, that potentiates the antiepileptogenic effect of some AEDs. Based on this, this review discusses the main mechanisms involved in epileptogenesis, as well as its pharmacological approach.

Spatio-Temporal Alterations in Synaptic Density During Epileptogenesis in the Rat Brain

Synaptic vesicle glycoprotein 2A (SV2A) is a transmembrane protein that binds levetiracetam and is involved in neurotransmission via an unknown mechanism. SV2A-immunoreactivity is reduced in animal models of epilepsy, and in postmortem hippocampi from patients with temporal lobe epilepsy. It is not known if other regions outside the hippocampus are affected in epilepsy, and whether SV2A is expression permanently reduced or regulated over time. In this study, we induced a generalized status epilepticus (SE) by systemic administration of lithium-pilocarpine to adult female rats. The brains from all animals experiencing SE were collected at different time points after the treatment. The radiotracer, [¹¹C]-UCB-J, binds to SV2A with high affinity, and has been used for in vivo imaging as an a-proxy marker for synaptic density. Here we determined the level of tritiated UCB-J binding by semiquantitative autoradiography in the cerebral cortex, hippocampus, thalamus, and hypothalamus, and in subregions of these. A prominent and highly significant reduction in SV2A binding capacity was observed over the first days after SE in the cerebral cortex and the hippocampus, but not in the thalamus and hypothalamus. The magnitude in reduction was larger and occurred earlier in the hippocampus and the piriform cortex, than in other cortical subregions. Interestingly, in all areas examined, the binding capacity returned to control levels 12 weeks after the SE comparable to the chronic phase. These data show that lithium-pilocarpine-induced epileptogenesis involves both loss and gain of synapses in the in a time-dependent manner.

The interplay of epilepsy with impaired mitophagy and autophagy linked dementia (MAD): A review of therapeutic approaches

The duration and, age of dementia have been linked to a higher risk of seizures. The exact mechanism that drives epileptogenesis in impaired mitophagy and autophagy linked dementia (MAD) is fully defined after reviewing the Scopus, Publon, and Pubmed databases. The epileptogenesis in patients with Alzheimer's disease dementia (ADD) and Parkinson's disease dementia (PDD) is due to involvement of amyloid plaques (Aβ), phosphorylated tau (pTau), Parkin, NF-kB and NLRP3 inflammasome. Microglia, the prime protective and inflammatory cells in the brain exert crosstalk between mitophagy and inflammation. Several researchers believed that the inflammatory brain cells microglia could be a therapeutic target for the treatment of a MAD associated epilepsy. There are conventional antiepileptic drugs such as gabapentin, lamotrigine, phenytoin sodium, carbamazepine, oxcarbazepine, felbamate, lamotrigine, valproate sodium, and topiramate are prescribed by a psychiatrist to suppress seizure frequency. Also, the conventional drugs generate serious adverse effects and synergises dementia characteristics. The adverse effect of carbamazepine is neurotoxic and also, damages haemopoietic system and respiratory tract. The phenytoin treatment causes cerebellar defect and anemia. Dementia and epilepsy have a complicated relationship, thus targeting mitophagy for cure of epileptic dementia makes sense. Complementary and alternative medicine (CAM) is one of the rising strategies by many patients of the world, not only to suppress seizure frequency but also to mitigate dementia characteristics of patients. Therefore our present review focus on the interplay between epilepsy and MAD and their treatment with CAM approaches.

Antiepileptic Therapy of Abrus cantoniensis: Evidence from Network Pharmacology

The present study explores the mechanism of antiepileptic treatment of Abrus cantoniensis through network pharmacology. During this process, several databases were recruited, e.g., the TCMSP database, HERB database, and SwissTargetPrediction database were used to retrieve the active components and targets of Abrus cantoniensis; GeneCards database and OMIM database were used to retrieve the targets of epilepsy. The targets of epilepsy and Abrus cantoniensis were subjected to target intersection in venny2.1, and protein interaction analysis of Abrus cantoniensis in the String database. We set the Cyto NCA plug-in condition as betweenness; selected the first 8 genes of betweenness as the core genes; performed the integrative bioinformatics of candidates by GO analysis and KEGG analysis. Moreover, AutoDockTools and AutoDockVina software were used to perform the molecular docking; Pymol was used to perform the docking visualization. We obtained three active components of Abrus cantoniensis, which are mainly related to β-sitosterol and stigmasterol; 92 intersection targets of epilepsy of Abrus cantoniensis, including 9 core targets such as AKT1, ESR1, MMP9, CES1, SRC, HIF1A, ABCB1, CASP3, and SNCA; 8 core targets were flavanone constituent proteins. Define p value less than 0.05; according to the screening principle, the first 20 GO pathways and KEGG pathways were selected. We found that Abrus cantoniensis was mainly connected with epilepsy through the neuroactive ligand-receptor interaction signaling pathway, the neurodegeneration pathway, and multiple disease signaling pathway; the docking between ESR1 and components is the most stable among the core targets. Besides, the binding energies of the core targets were all less than −5 kcal mol⁻¹. Taken together, the current research provides a new strategy for the antiepileptic treatment of Abrus cantoniensis.

Connectivity Mapping Using a Novel sv2a Loss-of-Function Zebrafish Epilepsy Model as a Powerful Strategy for Anti-epileptic Drug Discovery

Synaptic vesicle glycoprotein 2A (SV2A) regulates action potential-dependent neurotransmitter release and is commonly known as the primary binding site of an approved anti-epileptic drug, levetiracetam. Although several rodent knockout models have demonstrated the importance of SV2A for functional neurotransmission, its precise physiological function and role in epilepsy pathophysiology remains to be elucidated. Here, we present a novel sv2a knockout model in zebrafish, a vertebrate with complementary advantages to rodents. We demonstrated that 6 days post fertilization homozygous sv2a^–/– mutant zebrafish larvae, but not sv2a^+/– and sv2a^+/+ larvae, displayed locomotor hyperactivity and spontaneous epileptiform discharges, however, no major brain malformations could be observed. A partial rescue of this epileptiform brain activity could be observed after treatment with two commonly used anti-epileptic drugs, valproic acid and, surprisingly, levetiracetam. This observation indicated that additional targets, besides Sv2a, maybe are involved in the protective effects of levetiracetam against epileptic seizures. Furthermore, a transcriptome analysis provided insights into the neuropathological processes underlying the observed epileptic phenotype. While gene expression profiling revealed only one differentially expressed gene (DEG) between wildtype and sv2a^+/– larvae, there were 4386 and 3535 DEGs between wildtype and sv2a^–/–, and sv2a^+/– and sv2a^–/– larvae, respectively. Pathway and gene ontology (GO) enrichment analysis between wildtype and sv2a^–/– larvae revealed several pathways and GO terms enriched amongst up- and down-regulated genes, including MAPK signaling, synaptic vesicle cycle, and extracellular matrix organization, all known to be involved in epileptogenesis and epilepsy. Importantly, we used the Connectivity map database to identify compounds with opposing gene signatures compared to the one observed in sv2a^–/– larvae, to finally rescue the epileptic phenotype. Two out of three selected compounds rescued electrographic discharges in sv2a^–/– larvae, while negative controls did not. Taken together, our results demonstrate that sv2a deficiency leads to increased seizure vulnerability and provide valuable insight into the functional importance of sv2a in the brain in general. Furthermore, we provided evidence that the concept of connectivity mapping represents an attractive and powerful approach in the discovery of novel compounds against epilepsy.

Expression profile of synaptic vesicle glycoprotein 2A, B, and C paralogues in temporal neocortex tissue from patients with temporal lobe epilepsy (TLE)

Synaptic vesicle glycoprotein-2 (SV2) is a family of proteins consisting of SV2A, SV2B, and SV2C. This protein family has attracted attention in recent years after SV2A was shown to be an epileptic drug target and a perhaps a biomarker of synaptic density. So far, the anatomical localization of these proteins in the rodent and human brain have been reported, but co-expression of SV2 genes on a cellular level, their expressions in the human brain, comparison to radioligand binding, any possible regulation in epilepsy are not known. We have here analyzed the expression of SV2 genes in neuronal subtypes in the temporal neocortex in selected specimens by using single nucleus-RNA sequencing, and performed quantitative PCR in populations of temporal lobe epilepsy (TLE) patients and healthy controls. [3H]-UCB-J autoradiography was performed to analyze the correlation between the mRNA transcript and binding capacity to SV2A. Our data showed that the SV2A transcript is expressed in all glutamatergic and GABAergic cortical subtypes, while SV2B expression is restricted to only the glutamatergic neurons and SV2C has very limited expression in a small subgroup of GABAergic interneurons. The level of [3H]-UCB-J binding and the concentration of SV2A mRNA is strongly correlated in each patient, and the expression is lower in the TLE patients. There is no relationship between SV2A expression and age, sex, seizure frequency, duration of epilepsy, or whether patients were recently treated with levetiracetam or not. Collectively, these findings point out a neuronal subtype-specific distribution of the expression of the three SV2 genes, and the lower levels of both radioligand binding and expression further emphasize the significance of these proteins in this disease.

[18F]BIBD-181: A Novel Positron Emission Tomography Tracer Specific for Synaptic Vesicle Glycoprotein 2A

Dysfunction or decreased expression of synaptic vesicle glycoprotein 2A (SV2A) is closely related to the progression of neurodegenerative diseases and psychiatric disorders. The development of positron emission tomography (PET) tracers targeting SV2A can provide a strong imaging basis for the diagnosis and treatment of these diseases. Herein we report the synthesis of the novel radiotracer [¹⁸F]BIBD-181 and its preclinical evaluation. The absolute configuration of BIBD-181 was confirmed by the single-crystal structure of its precursor. The in vitro binding assay of BIBD-181 showed high SV2A binding affinity. Compared with previously reported tracers, [¹⁸F]BIBD-181 has mild labeling conditions, simple operation, and high yield. The in vivo metabolism of [¹⁸F]BIBD-181 is similar to that of UCB derivatives, and the metabolites do not interfere with brain PET imaging. Biodistribution and PET studies showed that [¹⁸F]BIBD-181 has high brain uptake and good pharmacokinetics. Autoradiography and PET inhibition studies indicated that [¹⁸F]BIBD-181 specifically binds SV2A. Because [¹⁸F]BIBD-181 exhibits excellent properties, it may be a reliable probe of quantities for SV2A-related disease diagnosis.

Mechanisms Involved in Epileptogenesis in Alzheimer's Disease and Their Therapeutic Implications

Epilepsy and Alzheimer's disease (AD) incidence increases with age. There are reciprocal relationships between epilepsy and AD. Epilepsy is a risk factor for AD and, in turn, AD is an independent risk factor for developing epilepsy in old age, and abnormal AD biomarkers in PET and/or CSF are frequently found in late-onset epilepsies of unknown etiology. Accordingly, epilepsy and AD share pathophysiological processes, including neuronal hyperexcitability and an early excitatory-inhibitory dysregulation, leading to dysfunction in the inhibitory GABAergic and excitatory glutamatergic systems. Moreover, both β-amyloid and tau protein aggregates, the anatomopathological hallmarks of AD, have proepileptic effects. Finally, these aggregates have been found in the resection material of refractory temporal lobe epilepsies, suggesting that epilepsy leads to amyloid and tau aggregates. Some epileptic syndromes, such as medial temporal lobe epilepsy, share structural and functional neuroimaging findings with AD, leading to overlapping symptomatology, such as episodic memory deficits and toxic synergistic effects. In this respect, the existence of epileptiform activity and electroclinical seizures in AD appears to accelerate the progression of cognitive decline, and the presence of cognitive decline is much more prevalent in epileptic patients than in elderly patients without epilepsy. Notwithstanding their clinical significance, the diagnosis of clinical seizures in AD is a challenge. Most are focal and manifest with an altered level of consciousness without motor symptoms, and are often interpreted as cognitive fluctuations. Finally, despite the frequent association of epilepsy and AD dementia, there is a lack of clinical trials to guide the use of antiseizure medications (ASMs). There is also a potential role for ASMs to be used as disease-modifying drugs in AD.

Levetiracetam Mechanisms of Action: From Molecules to Systems

Epilepsy is a chronic disease that affects millions of people worldwide. Antiepileptic drugs (AEDs) are used to control seizures. Even though parts of their mechanisms of action are known, there are still components that need to be studied. Therefore, the search for novel drugs, new molecular targets, and a better understanding of the mechanisms of action of existing drugs is still crucial. Levetiracetam (LEV) is an AED that has been shown to be effective in seizure control and is well-tolerable, with a novel mechanism of action through an interaction with the synaptic vesicle protein 2A (SV2A). Moreover, LEV has other molecular targets that involve calcium homeostasis, the GABAergic system, and AMPA receptors among others, that might be integrated into a single mechanism of action that could explain the antiepileptogenic, anti-inflammatory, neuroprotective, and antioxidant properties of LEV. This puts it as a possible multitarget drug with clinical applications other than for epilepsy. According to the above, the objective of this work was to carry out a comprehensive and integrative review of LEV in relation to its clinical uses, structural properties, therapeutical targets, and different molecular, genetic, and systemic action mechanisms in order to consider LEV as a candidate for drug repurposing.

All-optical monitoring of excitation-secretion coupling demonstrates that SV2A functions downstream of evoked Ca2+ entry

SV2A, an essential transporter-like synaptic vesicle protein, is a major target for antiepileptic drugs and a receptor for clostridial neurotoxins including Botox. While SV2A is required for normal levels of evoked neurotransmitter release, the mechanism underlying this role remains unclear. Here, we introduce a new chemogenetic approach for all-optical monitoring of excitation-secretion coupling, and we demonstrate its use in characterizing the SV2A knockout (KO) phenotype in cultured hippocampal neurons. This method employs the HaloTag system to target a robust small-molecule Ca²⁺ indicator, JF₆₄₆ -BAPTA, to the presynaptic compartment. The far-red fluorescence of this indicator enables multiplexing with the fluorescent glutamate sensor iGluSnFR for detection of presynaptic Ca²⁺ influx and glutamate release at the same axonal boutons. Evoked glutamate release probability was reduced in SV2A KO neurons without a change in presynaptic Ca²⁺ entry, suggesting that SV2A supports vesicle fusion by increasing the functional availability, or efficiency, of the Ca²⁺ -regulated membrane fusion machinery. KEY POINTS: One of the most prescribed antiepileptic medications, levetiracetam, acts by binding a protein of uncertain molecular function. This transporter-like protein, SV2A, is trafficked to synaptic vesicles and acts to support neurotransmitter release, but the mechanism underlying this function has not been determined In this study, we sought to establish whether SV2A changes Ca²⁺ signalling at nerve terminals, which is a key regulatory system for synaptic vesicle exocytosis. To do so, we adapted new chemogenetic tools to perform all-optical measurements of presynaptic Ca²⁺ and glutamate release in neurons lacking SV2A. Our measurements showed that loss of SV2A reduces glutamate release without reducing Ca²⁺ influx at hippocampal nerve terminals, demonstrating that SV2A increases the likelihood that Ca²⁺ will trigger synaptic vesicle fusion.

The novel dual-mechanism Kv7 potassium channel/TSPO receptor activator GRT-X is more effective than the Kv7 channel opener retigabine in the 6-Hz refractory seizure mouse model

Epilepsy, one of the most common and most disabling neurological disorders, is characterized by spontaneous recurrent seizures, often associated with structural brain alterations and cognitive and psychiatric comorbidities. In about 30% of patients, the seizures are resistant to current treatments; so more effective treatments are urgently needed. Among the ∼30 clinically approved antiseizure drugs, retigabine (ezogabine) is the only drug that acts as a positive allosteric modulator (or opener) of voltage-gated Kv7 potassium channels, which is particularly interesting for some genetic forms of epilepsy. Here we describe a novel dual-mode-of-action compound, GRT-X (N-[(3-fluorophenyl)-methyl]-1-(2-methoxyethyl)-4-methyl-2-oxo-(7-trifluoromethyl)-1H-quinoline-3-carboxylic acid amide) that activates both Kv7 potassium channels and the mitochondrial translocator protein 18 kDa (TSPO), leading to increased synthesis of brain neurosteroids. TSPO activators are known to exert anti-inflammatory, neuroprotective, anxiolytic, and antidepressive effects, which, together with an antiseizure effect (mediated by Kv7 channels), would be highly relevant for the treatment of epilepsy. This prompted us to compare the antiseizure efficacy of retigabine and GRT-X in six mouse and rat models of epileptic seizures, including the 6-Hz model of difficult-to-treat focal seizures. Furthermore, the tolerability of the two compounds was compared in mice and rats. Potency comparisons were based on both doses and peak plasma concentrations. Overall, GRT-X was more effective than retigabine in three of the six seizure models used here, the most important difference being the high efficacy in the 6-Hz (32 mA) seizure model in mice. Based on drug plasma levels, GRT-X was at least 30 times more potent than retigabine in the latter model. These data indicate that GRT-X is a highly interesting novel anti-seizure drug with a unique (first-in-class) dual-mode mechanism of action.

Effect of antiepileptic drug levetiracetam on cochlear function

BACKGROUND

Levetiracetam (LEV, 5-100 mg/kg) has been shown to prevent audiogenic seizures in a dose-dependent manner. This chemical is known to bind to synaptic vesicle protein 2A and inhibit l-type calcium channels, affecting neurotransmitter release. We hypothesize that the drug prevents audiogenic seizures partially by affecting cochlear neural response.

METHODS

To test this hypothesis, rats were given 1000, 500, 50, or 0 mg/kg (saline control) LEV-injection. Distortion product otoacoustic emissions (DPOAE), reflecting outer hair cell (OHC) function, and cochlear compound action potentials (CAP), reflecting cochlear neural output, were recorded and compared pre- and post-LEV.

RESULTS

1000 mg/kg LEV-injection did not significantly affect DPOAE. The high dose LEV-injection, however, significantly reduced CAP amplitude resulting threshold shift (TS), prolonged CAP latency, and enhanced CAP forward masking. CAP latency and forward masking were significantly affected at the 500 mg/kg dose, but CAP-TS remained unchanged after LEV-injection. Interestingly, CAP latency wassignificantly prolonged, at least at the low stimulation levels, although the amplitude of CAP remained constant after a clinical dose of LEV-injection (50 mg/kg).

DISCUSSION

Since the clinical dose of LEV-injection does not reduce CAP amplitude, the reduction of cochlear neural output is unlikely to be the underlying mechanism of LEV in the treatment of audiogenic seizure. The delayed cochlear neural response may be partially related to the prevention of audiogenic seizure. However, neuropharmacological changes in the central nervous system must play a major role in the treatment of audiogenic seizure, as it does in the treatment of focal epilepsy.

Deprescribing to Resolve Oversedation and Confusion in an Older Person Treated for Auditory Hallucinations and Poststroke Seizure Prophylaxis

This case study reviews the pharmacotherapy of a resident in a long-term care facility being treated for poststroke seizure, hallucinations, and dementia, a geriatric syndrome that is both common in regard to its prevalence and severe in regard to its impact on the individual, families, caregivers, and health care system. This case describes the past medical history of an older resident in a skilled nursing facility that was receiving pharmacological therapy for auditory hallucinations and for poststroke seizure prophylaxis, was noted to be having side effects from drug therapy, and how the nursing staff communicated with the consultant pharmacist to resolve these issues.

Interdependence of neural network dysfunction and microglial alterations in Alzheimer's disease-related models

Nonconvulsive epileptiform activity and microglial alterations have been detected in people with Alzheimer's disease (AD) and related mouse models. However, the relationship between these abnormalities remains to be elucidated. We suppressed epileptiform activity by treatment with the antiepileptic drug levetiracetam or by genetic ablation of tau and found that these interventions reversed or prevented aberrant microglial gene expression in brain tissues of aged human amyloid precursor protein transgenic mice, which simulate several key aspects of AD. The most robustly modulated genes included multiple factors previously implicated in AD pathogenesis, including TREM2, the hypofunction of which increases disease risk. Genetic reduction of TREM2 exacerbated epileptiform activity after mice were injected with kainate. We conclude that AD-related epileptiform activity markedly changes the molecular profile of microglia, inducing both maladaptive and adaptive alterations in their activities. Increased expression of TREM2 seems to support microglial activities that counteract this type of network dysfunction.

Positron Emission Computed Tomography Imaging of Synaptic Vesicle Glycoprotein 2A in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder seen in age-dependent dementia. There is currently no effective treatment for AD, which may be attributed in part to lack of a clear underlying mechanism. Early diagnosis of AD is of great significance to control the development of the disease. Synaptic loss is an important pathology in the early stage of AD, therefore the measurement of synaptic density using molecular imaging technology may be an effective way to early diagnosis of AD. Synaptic vesicle glycoprotein 2A (SV2A) is located in the presynaptic vesicle membrane of virtually all synapses. SV2A Positron Emission Computed Tomography (PET) could provide a way to measure synaptic density quantitatively in living humans and to track changes in synaptic density in AD. In view of the fact that synaptic loss is the pathology of both epilepsy and AD, this review summarizes the potential role of SV2A in the pathogenesis of AD, and suggests that SV2A should be used as an important target molecule of PET imaging agent for the early diagnosis of AD.

Levetiracetam promoted rat embryonic neurogenesis via NMDA receptor-mediated mechanism in vitro

AIMS

Levetiracetam (LEV) is a broad-spectrum antiepileptic drug with neuroprotective properties and novel mechanisms of action. Some evidence suggests that LEV may impact adult neurogenesis, but the results are controversial. The present study was aimed to evaluate the effects of LEV on the proliferation and differentiation of rat embryonic neural stem cells (NSCs) and to explore the role of GABAB or NMDA receptors.

MAIN METHODS

NSCs were isolated from rat fetal ganglionic eminence at embryonic day 14.5. The effects of LEV on viability, proliferation, neurosphere formation, and neuronal or astroglial differentiation of NSCs were assessed using resazurin, BrdU incorporation, immunocytochemistry, quantitative real-time PCR, and western blotting. Additionally, we addressed the relationship between treatment with NMDA and GABAB receptor antagonists (MK801 and saclofen, respectively) in combination with LEV on these parameters.

KEY FINDINGS

The data showed that LEV (50 μM) significantly increased the number (p < 0.01) and diameter of neurospheres (p < 0.05), enhanced proliferation (p < 0.01), and promoted neuronal differentiation, as revealed by significantly increased expressions of DCX and NeuN. The expressions of astroglial markers, GFAP and Olig2, were markedly reduced. The addition of MK801 (10 μM) significantly diminished neurospheres growth (p < 0.001), decreased the number of proliferating cells (p < 0.01), and reduced the number of new neurons (p < 0.001) but increased the astroglial cells (p < 0.001) induced by LEV. Co-treatment with saclofen (25 μM) did not significantly affect LEV-induced NSCs proliferation and differentiation.

SIGNIFICANCE

Our findings suggest that LEV may enhance rat embryonic neurogenesis mainly through an NMDA receptor-mediated mechanism.

Single-Target Versus Multi-Target Drugs Versus Combinations of Drugs With Multiple Targets: Preclinical and Clinical Evidence for the Treatment or Prevention of Epilepsy

Rationally designed multi-target drugs (also termed multimodal drugs, network therapeutics, or designed multiple ligands) have emerged as an attractive drug discovery paradigm in the last 10-20 years, as potential therapeutic solutions for diseases of complex etiology and diseases with significant drug-resistance problems. Such agents that modulate multiple targets simultaneously are developed with the aim of enhancing efficacy or improving safety relative to drugs that address only a single target or to combinations of single-target drugs. Although this strategy has been proposed for epilepsy therapy >25 years ago, to my knowledge, only one antiseizure medication (ASM), padsevonil, has been intentionally developed as a single molecular entity that could target two different mechanisms. This novel drug exhibited promising effects in numerous preclinical models of difficult-to-treat seizures. However, in a recent randomized placebo-controlled phase IIb add-on trial in treatment-resistant focal epilepsy patients, padsevonil did not separate from placebo in its primary endpoints. At about the same time, a novel ASM, cenobamate, exhibited efficacy in several randomized controlled trials in such patients that far surpassed the efficacy of any other of the newer ASMs. Yet, cenobamate was discovered purely by phenotype-based screening and its presumed dual mechanism of action was only described recently. In this review, I will survey the efficacy of single-target vs. multi-target drugs vs. combinations of drugs with multiple targets in the treatment and prevention of epilepsy. Most clinically approved ASMs already act at multiple targets, but it will be important to identify and validate new target combinations that are more effective in drug-resistant epilepsy and eventually may prevent the development or progression of epilepsy.

Promising drug targets and associated therapeutic interventions in Parkinson's disease

Parkinson's disease (PD) is one of the most debilitating brain diseases. Despite the availability of symptomatic treatments, response towards the health of PD patients remains scarce. To fulfil the medical needs of the PD patients, an efficacious and etiological treatment is required. In this review, we have compiled the information covering limitations of current therapeutic options in PD, novel drug targets for PD, and finally, the role of some critical beneficial natural products to control the progression of PD.

Proteomic Analysis Unveils Expressional Changes in Cytoskeleton- and Synaptic Plasticity-Associated Proteins in Rat Brain Six Months after Withdrawal from Morphine

Drug withdrawal is associated with abstinence symptoms including deficits in cognitive functions that may persist even after prolonged discontinuation of drug intake. Cognitive deficits are, at least partially, caused by alterations in synaptic plasticity but the precise molecular mechanisms have not yet been fully identified. In the present study, changes in proteomic and phosphoproteomic profiles of selected brain regions (cortex, hippocampus, striatum, and cerebellum) from rats abstaining for six months after cessation of chronic treatment with morphine were determined by label-free quantitative (LFQ) proteomic analysis. Interestingly, prolonged morphine withdrawal was found to be associated especially with alterations in protein phosphorylation and to a lesser extent in protein expression. Gene ontology (GO) term analysis revealed enrichment in biological processes related to synaptic plasticity, cytoskeleton organization, and GTPase activity. More specifically, significant changes were observed in proteins localized in synaptic vesicles (e.g., synapsin-1, SV2a, Rab3a), in the active zone of the presynaptic nerve terminal (e.g., Bassoon, Piccolo, Rims1), and in the postsynaptic density (e.g., cadherin 13, catenins, Arhgap35, Shank3, Arhgef7). Other differentially phosphorylated proteins were associated with microtubule dynamics (microtubule-associated proteins, Tppp, collapsin response mediator proteins) and the actin–spectrin network (e.g., spectrins, adducins, band 4.1-like protein 1). Taken together, a six-month morphine withdrawal was manifested by significant alterations in the phosphorylation of synaptic proteins. The altered phosphorylation patterns modulating the function of synaptic proteins may contribute to long-term neuroadaptations induced by drug use and withdrawal.

Preclinical In Vitro and In Vivo Characterization of Synaptic Vesicle 2A-Targeting Compounds Amenable to F-18 Labeling as Potential PET Radioligands for Imaging of Synapse Integrity

PURPOSE

Current synaptic vesicle 2A (SV2A) positron emission tomography (PET) imaging agents include the nanomolar affinity probes [¹¹C]UCB-J and [¹⁸F]UCB-H derived from the anti-epileptic drug levitaracetam (Keppra®). An industry-utilized "de-risking" approach was used to carry out initial pharmacological characterization and to assess potential next-generation candidates amenable to F-18 radiolabeling for preliminary evaluation.

PROCEDURES

Radioligand binding methods were employed in mammalian brain homogenates to determine the SV2A affinity (K_d) and maximal binding capacity (B_max) of [³H]UCB-J. Novel leads were then screened to identify compounds minimally with comparable binding affinities with UCB-J in order to select a F-18-labeled candidate for subsequent in vivo assessment in rat. In parallel, mammalian brain tissue section autoradiography was performed to assess specific SV2A distribution.

RESULTS

[³H]UCB-J bound with high affinity to a single population of sites in the rat brain (K_d = 2.6 ± 0.25 nM; B_max = 810 ± 25 fmol/mg protein) and control human cortex (K_d = 2.9 ± 0.54 nM; B_max = 10,000 ± 640 fmol/mg protein). Distribution of specific SV2A binding was shown to be homogeneous throughout the rodent brain and primarily in gray matter regions of rodent and human brain sections. Analog screening identified MNI-1038, MNI-1126/SDM-8, and SDM-2 as having comparable binding affinities with the currently available PET ligands. Subsequent [¹⁸F]MNI-1126/[¹⁸F]SDM-8 dynamic micro-PET imaging in rats revealed in vivo uptake and accumulation in the brain with favorable kinetics. Chase studies using 30 mg/kg levetiracetam confirmed that in vivo brain uptake of [¹⁸F]MNI-1126/[¹⁸F]SDM-8 was reversible.

CONCLUSIONS

Taken together, these data suggest [¹⁸F]MNI-1126/[¹⁸F]SDM-8 (since renamed as [¹⁸F]SynVesT-1) characterized via an in vitro screening cascade provided a measurable in vivo SV2A specific signal in the rodent brain. This tracer as well as the close analog [¹⁸F]SDM-2 (since renamed as [¹⁸F]SynVesT-2) is currently undergoing further evaluation in preclinical and clinical studies.

The Synaptic Vesicle Protein 2A Interacts With Key Pathogenic Factors in Alzheimer's Disease: Implications for Treatment

Alzheimer’s disease (AD), a serious neurodegenerative disease, is pathologically characterized by synaptic loss and dysfunction. Synaptic vesicle protein 2A (SV2A) is an indispensable vesicular protein specifically expressed in synapses and can be used as a biomarker for synaptic density. We found that the expression of SV2A was down-regulated in the hippocampus of AD patients, yet the relation of SV2A to other hallmarks of AD pathology such as amyloid precursor protein (APP), β-amyloid (Aβ), and Tau protein is not thoroughly clear. In addition, SV2A colocalized with APP and was down-regulated at Aβ deposition. Moreover, we found that SV2A deficiency leads to a simultaneous increase in Aβ and Tau hyperphosphorylation, while SV2A overexpression was associated with downregulation of β-site APP cleaving enzyme 1 and apolipoprotein E genes. In addition, evidence gained in the study points to the phosphatidylinositol 3-kinase signaling pathway as a possible mediator in SV2A regulation influencing the incidence and development of AD. With limited effective diagnostic methods for AD, a close interplay between SV2A and AD-related proteins demonstrated in our study may provide novel and innovative diagnostic and therapeutic opportunities.

The impairment of motor coordination following chronic carbamazepine-levetiracetam combination treatment with evidence of corticocerebellar toxicity in male Wistar rats

This study examined the effects of carbamazepine (CBZ) or levetiracetam (LEV) and sub-therapeutic doses of the combination of the two conventional antiepileptics on some of the markers of motor coordination. Twenty-four male Wistar rats (140 ± 5 g) were randomized into 4 groups (n = 6). Group I rats received physiological saline (0.2 ml), group II were administered CBZ (25.0 mg/kg), group III received LEV (50 mg/kg), while group IV rats were given sub-therapeutic doses of CBZ (12.5 mg/kg) and LEV (25 mg/kg) intraperitoneally for 28 days. Thereafter the animals were subjected to behavioral and biochemical investigations, while the frontal lobe and cerebellar tissue were preserved for histological investigation. Data were subjected to descriptive and inferential statistics, and the results presented as mean ± SEM, analyzed using one-way Analysis of variance (ANOVA) and Student- Newman Keuls post hoc analysis where appropriate. p < 0.05 was considered statistically significant. There was significant alteration in fine and skilled movement after the CBZ, and CBZ + LEV chronic treatment compared with the control. The CBZ, and CBZ + LEV combination treatment increased the frontal lobe and cerebellar activities of acetylcholinesterase, malondialdehyde concentration, tissue necrotic factor alpha and decreased the activities of super oxide dismutase relative to the control. Disorganization of the histoarchitecture of the frontal lobe and cerebellum was characterized by cellular atrophy, chromatolysis and hyalinization. Chronic CBZ, and CBZ + LEV combination treatment produced psychomotor dysfunction and neurotoxicity in this order CBZ + LEV > CBZ > LEV in the rats.