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1.
Epilepsia ; 2022 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-36054499

RESUMO

OBJECTIVE: Pharmacokinetics (PK) of a drug drive its exposure, efficacy, and tolerability. A thorough preclinical PK assessment of antiseizure medications (ASMs) is therefore essential to evaluate the clinical potential. We tested protection against evoked seizures of prototype ASMs in conjunction with analysis of plasma and brain PK as a proof-of-principle study to enhance our understanding of drug efficacy and duration of action using rodent seizure models. METHODS: In vivo seizure protection assays were performed in adult male CF-1 mice and Sprague Dawley rats. Clobazam (CLB), N-desmethyl CLB (NCLB), carbamazepine (CBZ), CBZ-10,11-epoxide (CBZE), sodium valproate (VPA), and levetiracetam (LEV) concentrations were quantified in plasma and brain using liquid chromatography-tandem mass spectrometry. Mean concentrations of each analyte were calculated and used to determine PK parameters via noncompartmental analysis in Phoenix WinNonLin. RESULTS: NCLB concentrations were approximately 10-fold greater than CLB in mice. The antiseizure profile of CLB was partially sustained by NCLB in mice. CLB concentrations were lower in rats than in mice. CBZE plasma exposures were approximately 70% of CBZ in both mice and rats, likely contributing to the antiseizure effect of CBZ. VPA showed a relatively short half-life in both mice and rats, which correlated with a sharp decline in efficacy. LEV had a prolonged brain and plasma half-life, associated with a prolonged duration of action in mice. SIGNIFICANCE: The study demonstrates the utility of PK analyses for understanding the seizure protection time course in mice and rats. The data indicate that distinct PK profiles of ASMs between mice and rats likely drive differences in drug efficacy between rodent models.

2.
J Vis Exp ; (184)2022 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-35816000

RESUMO

One of the main causes of epilepsy is an infection of the central nervous system (CNS); approximately 8% of patients who survive such an infection develop epilepsy as a consequence, with rates being significantly higher in less economically developed countries. This work provides an overview of modeling epilepsy of infectious etiology and using it as a platform for novel antiseizure compound testing. A protocol of epilepsy induction by non-stereotactic intracerebral injection of Theiler's murine encephalomyelitis virus (TMEV) in C57BL/6 mice is presented, which replicates many of the early and chronic clinical symptoms of viral encephalitis and subsequent epilepsy in human patients. The clinical evaluation of mice during encephalitis to monitor seizure activity and detect the potential antiseizure effects of novel compounds is described. Furthermore, histopathological consequences of viral encephalitis and seizures such as hippocampal damage and neuroinflammation are shown, as well as long-term consequences such as spontaneous epileptic seizures. The TMEV model is one of the first translational, infection-driven, experimental platforms to allow for the investigation of the mechanisms of epilepsy development as a consequence of CNS infection. Thus, it also serves to identify potential therapeutic targets and compounds for patients at risk of developing epilepsy following a CNS infection.


Assuntos
Encefalite Viral , Epilepsia , Theilovirus , Animais , Modelos Animais de Doenças , Epilepsia/etiologia , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Convulsões/diagnóstico , Theilovirus/fisiologia
3.
Epilepsia Open ; 7(1): 46-58, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34668659

RESUMO

OBJECTIVE: Infection with Theiler's murine encephalomyelitis virus (TMEV) in C57Bl/6J mice results in handling-induced seizures and is useful for evaluating compounds effective against infection-induced seizures. However, to date only a few compounds have been evaluated in this model, and a comprehensive study of antiseizure medications (ASMs) has not yet been performed. Furthermore, as the TMEV infection produces marked neuroinflammation, an evaluation of prototype anti-inflammatory compounds is needed as well. METHODS: Male C57Bl/6J mice were inoculated with TMEV (day 0) followed by daily administrations of test compounds (day 3-7) and subsequent handling sessions (day 3-7). Doses of ASMs, comprising several mechanistic classes, were selected based on previously published data demonstrating the effect of these compounds in reducing seizures in the 6 Hz model of pharmacoresistant seizures. Doses of anti-inflammatory compounds, comprising several mechanistic classes, were selected based on published evidence of reduction of inflammation or inflammation-related endpoints. RESULTS: Several prototype ASMs reduced acute seizures following TMEV infection: lacosamide, phenytoin, ezogabine, phenobarbital, tiagabine, gabapentin, levetiracetam, topiramate, and sodium valproate. Of these, phenobarbital and sodium valproate had the greatest effect (>95% seizure burden reduction). Prototype anti-inflammatory drugs celecoxib, dexamethasone, and prednisone also moderately reduced seizure burden. SIGNIFICANCE: The TMEV model is utilized by the Epilepsy Therapy Screening Program (ETSP) as a tool for evaluation of novel compounds. Compounds reducing seizures in the TMEV comprise distinct mechanistic classes, some with mechanisms of action that extend beyond traditional ASMs.


Assuntos
Epilepsia , Theilovirus , Animais , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Modelos Animais de Doenças , Masculino , Camundongos , Convulsões/tratamento farmacológico
4.
Exp Neurol ; 349: 113954, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34922908

RESUMO

The discovery and development of novel antiseizure drugs (ASDs) that are effective in controlling pharmacoresistant spontaneous recurrent seizures (SRSs) continues to represent a significant unmet clinical need. The Epilepsy Therapy Screening Program (ETSP) has undertaken efforts to address this need by adopting animal models that represent the salient features of human pharmacoresistant epilepsy and employing these models for preclinical testing of investigational ASDs. One such model that has garnered increased interest in recent years is the mouse variant of the Intra-Amygdala Kainate (IAK) microinjection model of mesial temporal lobe epilepsy (MTLE). In establishing a version of this model, several methodological variables were evaluated for their effect(s) on pertinent quantitative endpoints. Although administration of a benzodiazepine 40 min after kainate (KA) induced status epilepticus (SE) is commonly used to improve survival, data presented here demonstrates similar outcomes (mortality, hippocampal damage, latency periods, and 90-day SRS natural history) between mice given midazolam and those that were not. Using a version of this model that did not interrupt SE with a benzodiazepine, a 90-day natural history study was performed and survival, latency periods, SRS frequencies and durations, and SRS clustering data were quantified. Finally, an important step towards model adoption is to assess the sensitivities or resistances of SRSs to a panel of approved and clinically used ASDs. Accordingly, the following ASDs were evaluated for their effects on SRSs in these mice: phenytoin (20 mg/kg, b.i.d.), carbamazepine (30 mg/kg, t.i.d.), valproate (240 mg/kg, t.i.d.), diazepam (4 mg/kg, b.i.d.), and phenobarbital (25 and 50 mg/kg, b.i.d.). Valproate, diazepam, and phenobarbital significantly attenuated SRS frequency relative to vehicle controls at doses devoid of observable adverse behavioral effects. Only diazepam significantly increased seizure freedom. Neither phenytoin nor carbamazepine significantly altered SRS frequency or freedom under these experimental conditions. These data demonstrate that SRSs in this IAK model of MTLE are pharmacoresistant to two representative sodium channel-inhibiting ASDs (phenytoin and carbamazepine) and partially sensitive to GABA receptor modulating ASDs (diazepam and phenobarbital) or a mixed-mechanism ASD (valproate). Accordingly, this model is being incorporated into the NINDS-funded ETSP testing platform for treatment resistant epilepsy.


Assuntos
Tonsila do Cerebelo , Anticonvulsivantes/uso terapêutico , Convulsivantes , Epilepsia do Lobo Temporal/induzido quimicamente , Epilepsia do Lobo Temporal/tratamento farmacológico , Ácido Caínico , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Animais , Comportamento Animal , Convulsivantes/administração & dosagem , Diazepam/uso terapêutico , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos/métodos , Epilepsia Resistente a Medicamentos/induzido quimicamente , Epilepsia Resistente a Medicamentos/tratamento farmacológico , Epilepsia do Lobo Temporal/psicologia , Ácido Caínico/administração & dosagem , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microinjeções , Convulsões/psicologia , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/tratamento farmacológico
5.
Epilepsy Curr ; 21(6): 433-440, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34924851

RESUMO

Viral infection of the central nervous system increasingly places people at risk of developing life-threatening and treatment-resistant acute and chronic seizures (epilepsy). The emergence of new human viruses due to ongoing social, political, and ecological changes places people at risk more than ever before. The development of new preventative or curative strategies is critical to address this burden. However, our understanding of the complex relationship between viruses and the brain has been hindered by the lack of animal models that survive the initial infection and are amenable for long-term mechanistic, behavioral, and pharmacological studies in the process of viral-induced epileptogenesis. In this review, we focus on the Theiler's murine encephalomyelitis virus (TMEV) mouse model of viral infection-induced epilepsy. The TMEV model has a number of important advantages to address the quintessential processes underlying the development of epilepsy following a viral infection, as well as fuel new therapeutic development. In this review, we highlight the contributions of the TMEV model to our current understanding of the relationship between viral infection, inflammation, and seizures.

6.
Epilepsia ; 62(7): 1677-1688, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34080183

RESUMO

OBJECTIVE: The kainic acid (KA)-induced status epilepticus (SE) model in rats is a well-defined model of epileptogenesis. This model closely recapitulates many of the clinical and pathological characteristics of human temporal lobe epilepsy (TLE) that arise following SE or another neurological insult. Spontaneous recurrent seizures (SRS) in TLE can present after a latent period following a neurological insult (traumatic brain injury, SE event, viral infection, etc.). Moreover, this model is suitable for preclinical studies to evaluate the long-term process of epileptogenesis and screen putative disease-modifying/antiepileptogenic agents. The burden of human TLE is highly variable, similar to the post-KA SE rat model. In this regard, this model may have broad translational relevance. This report thus details the pharmacological characterization and methodological refinement of a moderate-throughput drug screening program using the post-KA-induced SE model of epileptogenesis in male Sprague Dawley rats to identify potential agents that may prevent or modify the burden of SRS. Specifically, we sought to demonstrate whether our protocol could prevent the development of SRS or lead to a reduced frequency/severity of SRS. METHODS: Rats were administered either everolimus (2-3 mg/kg po) beginning 1, 2, or 24 h after SE onset, or phenobarbital (60 mg/kg ip) beginning 1 h after SE onset. All treatments were administered once/day for 5-7 days. Rats in all studies (n = 12/treatment dose/study) were then monitored intermittently by video-electroencephalography (2 weeks on, 2 weeks off, 2 weeks on epochs) to determine latency to onset of SRS and disease burden. RESULTS: Although no adverse side effects were observed in our studies, no treatment significantly modified disease or prevented the presentation of SRS by 6 weeks after SE onset. SIGNIFICANCE: Neither phenobarbital nor everolimus administered at several time points after SE onset prevented the development of SRS. Nonetheless, we demonstrate a practical and moderate-throughput screen for potential antiepileptogenic agents in a rat model of TLE.


Assuntos
Anticonvulsivantes/uso terapêutico , Epilepsia do Lobo Temporal/prevenção & controle , Everolimo/uso terapêutico , Fenobarbital/uso terapêutico , Animais , Anticonvulsivantes/efeitos adversos , Peso Corporal , Convulsivantes , Efeitos Psicossociais da Doença , Modelos Animais de Doenças , Composição de Medicamentos , Descoberta de Drogas , Avaliação Pré-Clínica de Medicamentos , Eletroencefalografia , Epilepsia do Lobo Temporal/induzido quimicamente , Everolimo/efeitos adversos , Ensaios de Triagem em Larga Escala , Ácido Caínico , Masculino , Fenobarbital/efeitos adversos , Ratos , Ratos Sprague-Dawley , Convulsões/prevenção & controle
7.
Epilepsia Open ; 6(2): 276-296, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34033232

RESUMO

Epilepsy is one of the most common chronic brain diseases and is often associated with cognitive, behavioral, or other medical conditions. The need for therapies that would prevent, ameliorate, or cure epilepsy and the attendant comorbidities is a priority for both epilepsy research and public health. In 2018, the National Institute of Neurological Disease and Stroke (NINDS) convened a workshop titled "Accelerating the Development of Therapies for Antiepileptogenesis and Disease Modification" that brought together preclinical and clinical investigators and industry and regulatory bodies' representatives to discuss and propose a roadmap to accelerate the development of antiepileptogenic (AEG) and disease-modifying (DM) new therapies. This report provides a summary of the discussions and proposals of the Preclinical Science working group. Highlights of the progress of collaborative preclinical research projects on AEG/DM of ongoing research initiatives aiming to improve infrastructure and translation to clinical trials are presented. Opportunities and challenges of preclinical epilepsy research, vis-à-vis clinical research, were extensively discussed, as they pertain to modeling of specific epilepsy types across etiologies and ages, the utilization of preclinical models in AG/DM studies, and the strategies and study designs, as well as on matters pertaining to transparency, data sharing, and reporting research findings. A set of suggestions on research initiatives, infrastructure, workshops, advocacy, and opportunities for expanding the borders of epilepsy research were discussed and proposed as useful initiatives that could help create a roadmap to accelerate and optimize preclinical translational AEG/DM epilepsy research.


Assuntos
Epilepsia , Acidente Vascular Cerebral , Comorbidade , Epilepsia/tratamento farmacológico , Humanos , National Institute of Neurological Disorders and Stroke (USA) , Acidente Vascular Cerebral/complicações , Estados Unidos
8.
Epilepsia ; 62(7): 1665-1676, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34002394

RESUMO

OBJECTIVE: Dravet syndrome (DS) is a rare but catastrophic genetic epilepsy, with 80% of patients carrying a mutation in the SCN1A gene. Currently, no antiseizure drug (ASD) exists that adequately controls seizures. In the clinic, individuals with DS often present first with a febrile seizure and, subsequently, generalized tonic-clonic seizures that can continue throughout life. To facilitate the development of ASDs for DS, the contract site of the National Institute of Neurological Disorders and Stroke (NINDS) Epilepsy Therapy Screening Program (ETSP) has evaluated a mouse model of DS using the conditional knock-in Scn1aA1783V/WT mouse. METHODS: Survival rates and temperature thresholds for Scn1aA1783V/WT were determined. Prototype ASDs were administered via intraperitoneal injections at the time-to-peak effect, which was previously determined, prior to the induction of hyperthermia-induced seizures. ASDs were considered effective if they significantly increased the temperature at which Scn1aA1783V/WT mice had seizures. RESULTS: Approximately 50% of Scn1aA1783V/WT survive to adulthood and all have hyperthermia-induced seizures. The results suggest that hyperthermia-induced seizures in this model of DS are highly refractory to a battery of ASDs. Exceptions were clobazam, tiagabine, levetiracetam, and the combination of clobazam and valproic acid with add-on stiripentol, which elevated seizure thresholds. SIGNIFICANCE: Overall, the data demonstrate that the proposed model for DS is suitable for screening novel compounds for the ability to block hyperthermia-induced seizures and that heterozygous mice can be evaluated repeatedly over the course of several weeks, allowing for higher throughput screening.


Assuntos
Anticonvulsivantes/uso terapêutico , Epilepsias Mioclônicas/tratamento farmacológico , Convulsões/tratamento farmacológico , Convulsões/etiologia , Animais , Temperatura Corporal , Dioxolanos/uso terapêutico , Epilepsia Resistente a Medicamentos/genética , Quimioterapia Combinada , Epilepsias Mioclônicas/genética , Feminino , Técnicas de Introdução de Genes , Ensaios de Triagem em Larga Escala , Hipertermia/complicações , Injeções Intraperitoneais , Masculino , Camundongos , Canal de Sódio Disparado por Voltagem NAV1.1/genética , National Institute of Neurological Disorders and Stroke (USA) , Estados Unidos
10.
Nat Rev Neurol ; 17(4): 231-242, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33594276

RESUMO

Onset of many forms of epilepsy occurs after an initial epileptogenic insult or as a result of an identified genetic defect. Given that the precipitating insult is known, these epilepsies are, in principle, amenable to secondary prevention. However, development of preventive treatments is difficult because only a subset of individuals will develop epilepsy and we cannot currently predict which individuals are at the highest risk. Biomarkers that enable identification of these individuals would facilitate clinical trials of potential anti-epileptogenic treatments, but no such prognostic biomarkers currently exist. Several putative molecular, imaging, electroencephalographic and behavioural biomarkers of epileptogenesis have been identified, but clinical translation has been hampered by fragmented and poorly coordinated efforts, issues with inter-model reproducibility, study design and statistical approaches, and difficulties with validation in patients. These challenges demand a strategic roadmap to facilitate the identification, characterization and clinical validation of biomarkers for epileptogenesis. In this Review, we summarize the state of the art with respect to biomarker research in epileptogenesis and propose a five-phase roadmap, adapted from those developed for cancer and Alzheimer disease, that provides a conceptual structure for biomarker research.


Assuntos
Biomarcadores , Eletroencefalografia , Epilepsia/diagnóstico , MicroRNAs , Neuroimagem , Animais , Biomarcadores/sangue , Biomarcadores/líquido cefalorraquidiano , Epilepsia/sangue , Epilepsia/líquido cefalorraquidiano , Epilepsia/fisiopatologia , Humanos , MicroRNAs/sangue , MicroRNAs/líquido cefalorraquidiano , Guias de Prática Clínica como Assunto
11.
J Neuroinflammation ; 17(1): 369, 2020 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-33272299

RESUMO

BACKGROUND: Neuron-glial antigen 2 (NG2) cells are a glial cell type tiled throughout the gray and white matter of the central nervous system (CNS). NG2 cells are known for their ability to differentiate into oligodendrocytes and are commonly referred to as oligodendrocyte precursor cells. However, recent investigations have begun to identify additional functions of NG2 cells in CNS health and pathology. NG2 cells form physical and functional connections with neurons and other glial cell types throughout the CNS, allowing them to monitor and respond to the neural environment. Growing evidence indicates that NG2 cells become reactive under pathological conditions, though their specific roles are only beginning to be elucidated. While reactive microglia and astrocytes are well-established contributors to neuroinflammation and the development of epilepsy following CNS infection, the dynamics of NG2 cells remain unclear. Therefore, we investigated NG2 cell reactivity in a viral-induced mouse model of temporal lobe epilepsy. METHODS: C57BL6/J mice were injected intracortically with Theiler's murine encephalomyelitis virus (TMEV) or PBS. Mice were graded twice daily for seizures between 3 and 7 days post-injection (dpi). At 4 and 14 dpi, brains were fixed and stained for NG2, the microglia/macrophage marker IBA1, and the proliferation marker Ki-67. Confocal z stacks were acquired in both the hippocampus and the overlying cortex. Total field areas stained by each cell marker and total field area of colocalized pixels between NG2 and Ki67 were compared between groups. RESULTS: Both NG2 cells and microglia/macrophages displayed increased immunoreactivity and reactive morphologies in the hippocampus of TMEV-injected mice. While increased immunoreactivity for IBA1 was also present in the cortex, there was no significant change in NG2 immunoreactivity in the cortex following TMEV infection. Colocalization analysis for NG2 and Ki-67 revealed a significant increase in overlap between NG2 and Ki-67 in the hippocampus of TMEV-injected mice at both time points, but no significant differences in cortex. CONCLUSIONS: NG2 cells acquire a reactive phenotype and proliferate in response to TMEV infection. These results suggest that NG2 cells alter their function in response to viral encephalopathy, making them potential targets to prevent the development of epilepsy following viral infection.


Assuntos
Epilepsia do Lobo Temporal/patologia , Hipocampo/patologia , Células Precursoras de Oligodendrócitos/patologia , Animais , Infecções por Cardiovirus , Proliferação de Células , Modelos Animais de Doenças , Epilepsia do Lobo Temporal/virologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microglia/patologia , Theilovirus
12.
Epilepsia ; 61(9): 1906-1918, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32761902

RESUMO

OBJECTIVE: Seizure detection is a major facet of electroencephalography (EEG) analysis in neurocritical care, epilepsy diagnosis and management, and the instantiation of novel therapies such as closed-loop stimulation or optogenetic control of seizures. It is also of increased importance in high-throughput, robust, and reproducible pre-clinical research. However, seizure detectors are not widely relied upon in either clinical or research settings due to limited validation. In this study, we create a high-performance seizure-detection approach, validated in multiple data sets, with the intention that such a system could be available to users for multiple purposes. METHODS: We introduce a generalized linear model trained on 141 EEG signal features for classification of seizures in continuous EEG for two data sets. In the first (Focal Epilepsy) data set consisting of 16 rats with focal epilepsy, we collected 1012 spontaneous seizures over 3 months of 24/7 recording. We trained a generalized linear model on the 141 features representing 20 feature classes, including univariate and multivariate, linear and nonlinear, time, and frequency domains. We tested performance on multiple hold-out test data sets. We then used the trained model in a second (Multifocal Epilepsy) data set consisting of 96 rats with 2883 spontaneous multifocal seizures. RESULTS: From the Focal Epilepsy data set, we built a pooled classifier with an Area Under the Receiver Operating Characteristic (AUROC) of 0.995 and leave-one-out classifiers with an AUROC of 0.962. We validated our method within the independently constructed Multifocal Epilepsy data set, resulting in a pooled AUROC of 0.963. We separately validated a model trained exclusively on the Focal Epilepsy data set and tested on the held-out Multifocal Epilepsy data set with an AUROC of 0.890. Latency to detection was under 5 seconds for over 80% of seizures and under 12 seconds for over 99% of seizures. SIGNIFICANCE: This method achieves the highest performance published for seizure detection on multiple independent data sets. This method of seizure detection can be applied to automated EEG analysis pipelines as well as closed loop interventional approaches, and can be especially useful in the setting of research using animals in which there is an increased need for standardization and high-throughput analysis of large number of seizures.


Assuntos
Eletrocorticografia/métodos , Epilepsias Parciais/diagnóstico , Aprendizado de Máquina , Convulsões/diagnóstico , Processamento de Sinais Assistido por Computador , Animais , Área Sob a Curva , Modelos Animais de Doenças , Eletroencefalografia , Epilepsias Parciais/fisiopatologia , Agonistas de Aminoácidos Excitatórios/toxicidade , Ácido Caínico/toxicidade , Modelos Lineares , Curva ROC , Ratos , Reprodutibilidade dos Testes , Convulsões/induzido quimicamente , Convulsões/fisiopatologia
13.
Epilepsia ; 61(6): 1301-1311, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32420627

RESUMO

OBJECTIVE: Approximately 30% of patients with epilepsy do not experience full seizure control on their antiseizure drug (ASD) regimen. Historically, screening for novel ASDs has relied on evaluating efficacy following a single administration of a test compound in either acute electrical or chemical seizure induction. However, the use of animal models of spontaneous seizures and repeated administration of test compounds may better differentiate novel compounds. Therefore, this approach has been instituted as part of the National Institute of Neurological Disorders and Stroke Epilepsy Therapy Screening Program screening paradigm for pharmacoresistant epilepsy. METHODS: Rats were treated with intraperitoneal kainic acid to induce status epilepticus and subsequent spontaneous recurrent seizures. After 12 weeks, rats were enrolled in drug screening studies. Using a 2-week crossover design, selected ASDs were evaluated for their ability to protect against spontaneous seizures, using a video-electroencephalographic monitoring system and automated seizure detection. Sixteen clinically available compounds were administered at maximally tolerated doses in this model. Dose intervals (1-3 treatments/d) were selected based on known half-lives for each compound. RESULTS: Carbamazepine (90 mg/kg/d), phenobarbital (30 mg/kg/d), and ezogabine (15 mg/kg/d) significantly reduced seizure burden at the doses evaluated. In addition, a dose-response study of topiramate (20-600 mg/kg/d) demonstrated that this compound reduced seizure burden at both therapeutic and supratherapeutic doses. However, none of the 16 ASDs conferred complete seizure freedom during the testing period at the doses tested. SIGNIFICANCE: Despite reductions in seizure burden, the lack of full seizure freedom for any ASD tested suggests that this screening paradigm may be useful for testing novel compounds with potential utility in pharmacoresistant epilepsy.


Assuntos
Anticonvulsivantes/administração & dosagem , Ácido Caínico/toxicidade , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/tratamento farmacológico , Animais , Avaliação Pré-Clínica de Medicamentos/métodos , Masculino , Ratos , Ratos Sprague-Dawley , Convulsões/fisiopatologia , Estado Epiléptico/fisiopatologia
14.
J Med Chem ; 63(11): 5865-5878, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32390424

RESUMO

Despite the availability of more than 25 antiseizure drugs on the market, approximately 30% of patients with epilepsy still suffer from seizures. Thus, the epilepsy therapy market has a great need for a breakthrough drug that will aid pharmacoresistant patients. In our previous study, we discovered a vitamin K analogue, 2h, which displayed modest antiseizure activity in zebrafish and mouse seizure models. However, there are limitations to this compound due to its pharmacokinetic profile. In this study, we develop a new series of vitamin K analogues by modifying the structure of 2h. Among these, compound 3d shows full protection in a rodent pharmacoresistant seizure model with limited rotarod motor toxicity and favorable pharmacokinetic properties. Furthermore, the brain/plasma concentration ratio of 3d indicates its excellent permeability into the brain. The resulting data shows that 3d can be further developed as a potential antiseizure drug in the clinic.


Assuntos
Anticonvulsivantes/uso terapêutico , Convulsões/tratamento farmacológico , Vitamina K/análogos & derivados , Administração Oral , Animais , Anticonvulsivantes/química , Anticonvulsivantes/farmacocinética , Anticonvulsivantes/farmacologia , Encéfalo/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sistema Enzimático do Citocromo P-450/química , Sistema Enzimático do Citocromo P-450/metabolismo , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Meia-Vida , Humanos , Isoenzimas/antagonistas & inibidores , Isoenzimas/metabolismo , Masculino , Camundongos , Convulsões/patologia , Relação Estrutura-Atividade , Vitamina K/farmacocinética , Vitamina K/farmacologia , Vitamina K/uso terapêutico , Peixe-Zebra
15.
Exp Neurol ; 326: 113196, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31935368

RESUMO

The persistent unresponsiveness of many of the acquired epilepsies to traditional antiseizure medications has motivated the search for prophylactic drug therapies that could reduce the incidence of epilepsy in this at risk population. These studies are based on the idea of a period of epileptogenesis that can follow a wide variety of brain injuries. Epileptogenesis is hypothesized to involve changes in the brain not initially associated with seizures, but which result finally in seizure prone networks. Understanding these changes will provide crucial clues for the development of prophylactic drugs. Using the repeated low-dose kainate rat model of epilepsy, we have studied the period of epileptogenesis following status epilepticus, verifying the latent period with continuous EEG monitoring. Focusing on ultrastructural properties of the tripartite synapse in the CA1 region of hippocampus we found increased astrocyte ensheathment around both the presynaptic and postsynaptic elements, reduced synaptic AMPA receptor subunit and perisynaptic astrocyte GLT-1 expression, and increased number of docked vesicles at the presynaptic terminal. These findings were associated with an increase in frequency of the mEPSCs observed in patch clamp recordings of CA1 pyramidal cells. The results suggest a complex set of changes, some of which have been associated with increasingly excitable networks such as increased vesicles and mEPSC frequency, and some associated with compensatory mechanisms, such as increased astrocyte ensheathment. The diversity of ultrastructural and electrophysiological changes observed during epileptogeneiss suggests that potential drug targets for this period should be broadened to include all components of the tripartite synapse.


Assuntos
Epilepsia do Lobo Temporal/patologia , Sinapses/patologia , Animais , Astrócitos/patologia , Região CA1 Hipocampal/patologia , Eletroencefalografia , Epilepsia do Lobo Temporal/induzido quimicamente , Agonistas de Aminoácidos Excitatórios , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Ácido Caínico , Masculino , Ratos , Ratos Sprague-Dawley , Receptores de AMPA/biossíntese , Estado Epiléptico/induzido quimicamente , Estado Epiléptico/patologia , Sinapses/ultraestrutura
16.
Neuropharmacology ; 166: 107811, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31790717

RESUMO

The Epilepsy Therapy Screening Program (ETSP), formerly known as the Anticonvulsant Screening Program (ASP), has played an important role in the preclinical evaluation of many of the antiseizure drugs (ASDs) that have been approved by the FDA and thus made available for the treatment of seizures. Recent changes to the animal models used at the contract site of the ETSP at the University of Utah have been implemented in an attempt to better model the unmet clinical needs of people with pharmacoresistant epilepsy and thus identify improved therapies. In this review, we describe the changes that have occurred over the last several years in the screening approach used at the contract site and, in particular, detail the pharmacology associated with several of the animal models and assays that are either new to the program or have been recently characterized in more depth. There is optimism that the refined approach used by the ETSP contract site, wherein etiologically relevant models that include those with spontaneous seizures are used, will identify novel, potentially disease modifying therapies for people with pharmacoresistant epilepsy and those at risk for developing epilepsy. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.


Assuntos
Anticonvulsivantes/uso terapêutico , Programas de Triagem Diagnóstica/tendências , Descoberta de Drogas/tendências , Epilepsia Resistente a Medicamentos/tratamento farmacológico , Convulsões/tratamento farmacológico , Animais , Anticonvulsivantes/farmacologia , Descoberta de Drogas/métodos , Avaliação Pré-Clínica de Medicamentos/métodos , Avaliação Pré-Clínica de Medicamentos/tendências , Epilepsia Resistente a Medicamentos/diagnóstico , Humanos , Excitação Neurológica/efeitos dos fármacos , Excitação Neurológica/fisiologia , Convulsões/diagnóstico
17.
Epilepsia Open ; 4(3): 431-442, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31440724

RESUMO

Objective: C57BL/6J mice infected with Theiler's murine encephalomyelitis virus (TMEV) develop acute behavioral seizures in the first week of infection and later develop chronic epilepsy. The TMEV model provides a useful platform to test novel antiseizure therapeutics. The present study was designed to test the efficacy of cannabidiol (CBD) in reducing acute seizures induced by viral infection. Methods: C57BL/6J mice were infected intracortically with 2 × 105 plaque-forming units of TMEV. Mice were divided into two treatment groups-1) CBD-treated mice and 2) vehicle-treated mice. Frequency and severity of acute seizures were evaluated by video-monitoring the mice four times daily by the experimenter blinded to the treatment group. Results: Cannabidiol (180 mg/kg; 360 mg/kg/day) decreased both the frequency and severity of acute behavioral seizures following TMEV infection, but 150 mg/kg of CBD did not improve overall seizure outcome. The time to peak effect (TPE) of CBD in the 6 Hz 32 mA psychomotor seizure test using C57BL/6J mice was observed at 2 hours post-CBD treatment. Interestingly, CBD (150 mg/kg) significantly reduced frequency and severity of TMEV-induced acute seizures at 2 hours post-CBD treatment. These results suggest that CBD could be effective in decreasing TMEV-induced acute seizures when the seizure test is conducted at the TPE of CBD. Significance: Cannabinoids are increasingly studied for their potential antiseizure effects. Several preclinical and clinical studies provide evidence that CBD could be an effective therapy for intractable epilepsies. The present study corroborates those previous findings and provides an opportunity to investigate pharmacokinetics, pharmacodynamics, and mechanism(s) of antiseizure effects of CBD in the TMEV model, which may help to design future clinical studies more effectively.

18.
Epilepsia Open ; 4(3): 452-463, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31440726

RESUMO

Objective: The lamotrigine-resistant amygdala kindling model uses repeated administration of a low dose of lamotrigine during the kindling process to produce resistance to lamotrigine, which also extends to some other antiseizure drugs (ASDs). This model of pharmacoresistant epilepsy has been incorporated into the testing scheme utilized by the Epilepsy Therapy Screening Program (ETSP). Although some ASDs have been evaluated in this model, a comprehensive evaluation of ASD prototypes has not been reported. Methods: Following depth electrode implantation and recovery, rats were exposed to lamotrigine (5 mg/kg, i.p.) prior to each stimulation during the kindling development process (~3 weeks). A test dose of lamotrigine was used to confirm that fully kindled rats were lamotrigine-resistant. Efficacy (unambiguous protection against electrically elicited convulsive seizures) was defined as a Racine score < 3 in the absence of overt compound-induced side effects. Various ASDs, comprising several mechanistic classes, were administered to fully kindled, lamotrigine-resistant rats. Where possible, multiple doses of each drug were administered in order to obtain median effective dose (ED50) values. Results: Five sodium channel blockers tested (eslicarbazepine, lacosamide, lamotrigine, phenytoin, and rufinamide) were either not efficacious or effective only at doses that were not well-tolerated in this model. In contrast, compounds targeting either GABA receptors (clobazam, clonazepam, phenobarbital) or GABA-uptake proteins (tiagabine) produced dose-dependent efficacy against convulsive seizures. Compounds acting to modulate Ca2+ channels show differential activity: Ethosuximide was not effective, whereas gabapentin was moderately efficacious. Ezogabine and valproate were also highly effective, whereas topiramate and levetiracetam were not effective at the doses tested. Significance: These results strengthen the conclusion that the lamotrigine-resistant amygdala kindling model demonstrates pharmacoresistance to certain ASDs, including, but not limited to, sodium channel blockers, and supports the utility of the model for helping to identify compounds with potential efficacy against pharmacoresistant seizures.

20.
Exp Neurol ; 318: 50-60, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31022385

RESUMO

The contribution of glial transporters to glutamate movement across the membrane has been identified as a potential target for anti-seizure therapies. Two such glutamate transporters, GLT-1 and system xc-, are expressed on glial cells, and modulation of their expression and function have been identified as a means by which seizures, neuronal injury, and gliosis can be reduced in models of brain injury. While GLT-1 is responsible for the majority of glutamate uptake in the brain, system xc- releases glutamate in the extracellular cleft in exchange for cystine and represents as such the major source of hippocampal extracellular glutamate. Using the Theiler's Murine Encephalomyelitis Virus (TMEV) model of viral-induced epilepsy, we have taken two well-studied approaches, one pharmacological, one genetic, to investigate the potential role(s) of GLT-1 and system xc- in TMEV-induced pathology. Our findings suggest that the methods we utilized to modulate these glial transporters, while effective in other models, are not sufficient to reduce the number or severity of behavioral seizures in TMEV-infected mice. However, genetic knockout of xCT, the specific subunit of system xc-, may have cellular effects, as we observed a slight decrease in neuronal injury caused by TMEV and an increase in astrogliosis in the CA1 region of the hippocampus. Furthermore, xCT knockout caused an increase in GLT-1 expression selectively in the cortex. These findings have significant implications for both the characterization of the TMEV model as well as for future efforts to discover novel and effective anti-seizure drugs.


Assuntos
Sistema y+ de Transporte de Aminoácidos/metabolismo , Transportador 2 de Aminoácido Excitatório/metabolismo , Convulsões/metabolismo , Animais , Encéfalo/patologia , Infecções por Cardiovirus/complicações , Infecções por Cardiovirus/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Convulsões/patologia , Convulsões/virologia , Theilovirus
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