RESUMEN
Natural compounds are increasingly being studied for their potential neuroprotective effects against inflammatory neurological diseases. Epilepsy is a common neurological disease associated with inflammatory processes, and around 30% of people with epilepsy do not respond to traditional treatments. Some flavonoids, when taken along with antiseizure medications can help reduce the likelihood of drug-resistant epilepsy. Baicalin, a plant-based compound, has been shown to possess pharmacological properties such as anti-inflammatory, neuroprotective, anticonvulsant, and antioxidant activities. In this study, we tested the effect of baicalin on an established model of pharmacologically induced seizure in zebrafish using measures of both locomotor behavior and calcium imaging of neuronal activity. The results of our study showed that, at the tested concentration, and contrary to other studies in rodents, baicalin did not have an anti-seizure effect in zebrafish larvae. However, given its known properties, other concentrations and approaches should be explored to determine if it could potentially have other beneficial effects, either alone or when administered in combination with classic antiseizure medications.
Asunto(s)
Calcio , Flavonoides , Larva , Neuronas , Pentilenotetrazol , Convulsiones , Pez Cebra , Animales , Flavonoides/farmacología , Convulsiones/tratamiento farmacológico , Convulsiones/inducido químicamente , Larva/efectos de los fármacos , Calcio/metabolismo , Neuronas/efectos de los fármacos , Modelos Animales de Enfermedad , Anticonvulsivantes/farmacología , Relación Dosis-Respuesta a Droga , Convulsivantes/toxicidad , Locomoción/efectos de los fármacos , Actividad Motora/efectos de los fármacosRESUMEN
The voltage-gated calcium channel subunit α2δ-2 controls calcium-dependent signaling in neurons, and loss of this subunit causes epilepsy in both mice and humans. To determine whether mice without α2δ-2 demonstrate hippocampal activation or histopathological changes associated with seizure activity, we measured expression of the activity-dependent gene c-fos and various histopathological correlates of temporal lobe epilepsy (TLE) in hippocampal tissue from wild-type (WT) and α2δ-2 knock-out (CACNA2D2 KO) mice using immunohistochemical staining and confocal microscopy. Both genotypes demonstrated similarly sparse c-fos and ΔFosB expressions within the hippocampal dentate granule cell layer (GCL) at baseline, consistent with no difference in basal activity of granule cells between genotypes. Surprisingly, when mice were assayed 1â h after handling-associated convulsions, KO mice had fewer c-fos-positive cells but dramatically increased ΔFosB expression in the dentate gyrus compared with WT mice. After administration of a subthreshold pentylenetetrazol dose, however, KO mice dentate had significantly more c-fos expression compared with WT mice. Other histopathological markers of TLE in these mice, including markers of neurogenesis, glial activation, and mossy fiber sprouting, were similar between WT and KO mice, apart from a small but statistically significant increase in hilar mossy cell density, opposite to what is typically found in mice with TLE. This suggests that the differences in seizure-associated dentate gyrus function in the absence of α2δ-2 protein are likely due to altered functional properties of the network without associated structural changes in the hippocampus at the typical age of seizure onset.
Asunto(s)
Canales de Calcio , Hipocampo , Ratones Noqueados , Proteínas Proto-Oncogénicas c-fos , Convulsiones , Animales , Ratones , Canales de Calcio/metabolismo , Canales de Calcio/genética , Convulsivantes/toxicidad , Modelos Animales de Enfermedad , Hipocampo/metabolismo , Hipocampo/patología , Ratones Endogámicos C57BL , Neuronas/metabolismo , Neuronas/patología , Pentilenotetrazol , Proteínas Proto-Oncogénicas c-fos/metabolismo , Convulsiones/metabolismo , Convulsiones/genética , Convulsiones/patologíaRESUMEN
Neuroinflammation during the neonatal period has been linked to disorders such as autism and epilepsy. In this study, we investigated the early life behavioral consequences of a single injection of lipopolysaccharide (LPS) at postnatal day 10 (PD10) in mice. To assess deficits in communication, we performed the isolation-induced ultrasonic vocalizations (USVs) test at PD12. To determine if early life immune stimulus could alter seizure susceptibility, latency to flurothyl-induced generalized seizures was measured at 4 hours (hrs), 2 days, or 5 days after LPS injections. LPS had a sex-dependent effect on USV number. LPS-treated male mice presented significantly fewer USVs than LPS-treated female mice. However, the number of calls did not significantly differ between control and LPS for either sex. In male mice, we found that downward, short, and composite calls were significantly more prevalent in the LPS treatment group, while upward, chevron, and complex calls were less prevalent than in controls (p < 0.05). Female mice that received LPS presented a significantly higher proportion of short, frequency steps, two-syllable, and composite calls in their repertoire when compared with female control mice (p < 0.05). Seizure latency was not altered by early-life inflammation at any of the time points measured. Our findings suggest that early-life immune stimulation at PD10 disrupts vocal development but does not alter the susceptibility to flurothyl-induced seizures during the neonatal period. Additionally, the effect of inflammation in the disruption of vocalization is sex-dependent.
Asunto(s)
Animales Recién Nacidos , Lipopolisacáridos , Convulsiones , Caracteres Sexuales , Vocalización Animal , Animales , Femenino , Vocalización Animal/efectos de los fármacos , Vocalización Animal/fisiología , Ratones , Masculino , Lipopolisacáridos/farmacología , Lipopolisacáridos/toxicidad , Convulsiones/inducido químicamente , Flurotilo/toxicidad , Susceptibilidad a Enfermedades/inducido químicamente , Convulsivantes/toxicidad , Modelos Animales de EnfermedadRESUMEN
Drug-induced convulsions are a major challenge to drug development because of the lack of reliable biomarkers. Using machine learning, our previous research indicated the potential use of an index derived from heart rate variability (HRV) analysis in non-human primates as a biomarker for convulsions induced by GABAA receptor antagonists. The present study aimed to explore the application of this methodology to other convulsants and evaluate its specificity by testing non-convulsants that affect the autonomic nervous system. Telemetry-implanted males were administered various convulsants (4-aminopyridine, bupropion, kainic acid, and ranolazine) at different doses. Electrocardiogram data gathered during the pre-dose period were employed as training data, and the convulsive potential was evaluated using HRV and multivariate statistical process control. Our findings show that the Q-statistic-derived convulsive index for 4-aminopyridine increased at doses lower than that of the convulsive dose. Increases were also observed for kainic acid and ranolazine at convulsive doses, whereas bupropion did not change the index up to the highest dose (1/3 of the convulsive dose). When the same analysis was applied to non-convulsants (atropine, atenolol, and clonidine), an increase in the index was noted. Thus, the index elevation appeared to correlate with or even predict alterations in autonomic nerve activity indices, implying that this method might be regarded as a sensitive index to fluctuations within the autonomic nervous system. Despite potential false positives, this methodology offers valuable insights into predicting drug-induced convulsions when the pharmacological profile is used to carefully choose a compound.
Asunto(s)
4-Aminopiridina , Frecuencia Cardíaca , Aprendizaje Automático , Convulsiones , Animales , Masculino , Convulsiones/inducido químicamente , Frecuencia Cardíaca/efectos de los fármacos , 4-Aminopiridina/efectos adversos , Ácido Kaínico/toxicidad , Convulsivantes/toxicidad , Ranolazina , Bupropión/toxicidad , Bupropión/efectos adversos , Electrocardiografía/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Sistema Nervioso Autónomo/efectos de los fármacos , Sistema Nervioso Autónomo/fisiopatología , Telemetría , BiomarcadoresRESUMEN
A common way to investigate epilepsy and the effect of antiepileptic pharmaceuticals is to analyze the movement patterns of zebrafish larvae treated with different convulsants like pentylenetetrazol (PTZ), pilocarpine, etc. Many articles have been written on this topic, but the research methods and exact settings are not sufficiently defined in most. Here we designed and executed a series of experiments to optimize and standardize the zebrafish epilepsy model. We found that during the light and the dark trials, the zebrafish larvae moved significantly more in the light, independent of the treatment, both in PTZ and pilocarpine-treated and the control groups. As expected, zebrafish larvae treated with convulsants moved significantly more than the ones in the control group, although this difference was higher between the individuals treated with PTZ than pilocarpine. When examining the optimal observation time, we divided the half-hour period into 5-minute time intervals, and between these, the first 5 minutes were found to be the most different from the others. There were fewer significant differences in the total movement of larvae between the other time intervals. We also performed a linear regression analysis with the cumulative values of the distance moved during the time intervals that fit the straight line. In conclusion, we recommend 30 minutes of drug pretreatment followed by a 10-minute test in light conditions with a 5-minute accommodation time. Our result paves the way toward improved experimental designs using zebrafish to develop novel pharmaceutical approaches to treat epilepsy.
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Epilepsia , Pentilenotetrazol , Animales , Pentilenotetrazol/toxicidad , Pez Cebra , Convulsivantes/toxicidad , Pilocarpina/farmacología , Larva , Epilepsia/inducido químicamente , Epilepsia/tratamiento farmacológico , Anticonvulsivantes/farmacología , Anticonvulsivantes/uso terapéutico , Modelos Animales de EnfermedadRESUMEN
An effective in vitro screening assay to detect seizure liability in preclinical development can contribute to better lead molecule optimization prior to candidate selection, providing higher throughput and overcoming potential brain exposure limitations in animal studies. This study explored effects of 26 positive and 14 negative reference pharmacological agents acting through different mechanisms, including 18 reference agents acting on glutamate signaling pathways, in a brain slice assay (BSA) of adult rat to define the assay's sensitivity, specificity, and limitations. Evoked population spikes (PS) were recorded from CA1 pyramidal neurons of hippocampus (HPC) in the BSA. Endpoints for analysis were PS area and PS number. Most positive references (24/26) elicited a concentration-dependent increase in PS area and/or PS number. The negative references (14/14) had little effect on the PS. Moreover, we studied the effects of 15 reference agents testing positive in the BSA on spontaneous activity in E18 rat HPC neurons monitored with microelectrode arrays (MEA), and compared these effects to the BSA results. From these in vitro studies we conclude that the BSA provides 93% sensitivity and 100% specificity in prediction of drug-induced seizure liability, including detecting seizurogenicity by 3 groups of metabotropic glutamate receptor (mGluR) ligands. The MEA results seemed more variable, both quantitatively and directionally, particularly for endpoints capturing synchronized electrical activity. We discuss these results from the two models, comparing each with published results, and provide potential explanations for differences and future directions.
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Convulsivantes/toxicidad , Potenciales Evocados/efectos de los fármacos , Hipocampo/efectos de los fármacos , Neuronas/efectos de los fármacos , Convulsiones/inducido químicamente , Pruebas de Toxicidad , Animales , Células Cultivadas , Femenino , Edad Gestacional , Ácido Glutámico/metabolismo , Hipocampo/embriología , Hipocampo/metabolismo , Hipocampo/fisiopatología , Técnicas In Vitro , Ligandos , Masculino , Neuronas/metabolismo , Ratas Sprague-Dawley , Ratas Wistar , Receptores de Glutamato Metabotrópico/metabolismo , Reproducibilidad de los Resultados , Medición de Riesgo , Convulsiones/metabolismo , Convulsiones/fisiopatología , Transducción de SeñalRESUMEN
A number of currently used drugs have been obtained from medicinal plants which are a major source of drugs. These drugs are either used in their pure form or modified to a semisynthetic drug. Drug discovery through natural product research has been fruitful over the years. Traditionally, Calotropis procera is used extensively in the management of epilepsy. This study is conducted to explore the anticonvulsant effect of a hydroethanolic leaf extract of Calotropis procera (CPE) in murine models. This effect was evaluated using picrotoxin-induced convulsions, strychnine-induced convulsions, and isoniazid- and pilocarpine-induced status epilepticus in mice of both sexes. The results showed that CPE (100-300 mg/kg) exhibited an anticonvulsant effect against strychnine-induced clonic seizures by significantly reducing the duration (p = 0.0068) and frequency (p = 0.0016) of convulsions. The extract (100-300 mg/kg) caused a profound dose-dependent delay in the onset of clonic convulsions induced by picrotoxin (p < 0.0001) and tonic convulsions (p < 0.0001) in mice. The duration of convulsions was reduced significantly also for both clonic and tonic (p < 0.0001) seizures as well. CPE (100-300 mg/kg), showed a profound anticonvulsant effect and reduced mortality in the pilocarpine-induced convulsions. ED50 (~0.1007) determined demonstrated that the extract was less potent than diazepam in reducing the duration and onset of convulsions but had comparable efficacies. Flumazenil-a GABAA receptor antagonist-did not reverse the onset or duration of convulsions produced by the extract in the picrotoxin-induced seizure model. In isoniazid-induced seizure, CPE (300 mg kg1, p.o.) significantly (p < 0.001) delayed the onset of seizure in mice and prolonged latency to death in animals. Overall, the hydroethanolic leaf extract of Calotropis procera possesses anticonvulsant properties.
Asunto(s)
Anticonvulsivantes/uso terapéutico , Calotropis/química , Extractos Vegetales/uso terapéutico , Hojas de la Planta/química , Convulsiones/tratamiento farmacológico , Estado Epiléptico/tratamiento farmacológico , Animales , Anticonvulsivantes/aislamiento & purificación , Cromatografía Líquida de Alta Presión , Convulsivantes/toxicidad , Diazepam/uso terapéutico , Evaluación Preclínica de Medicamentos , Etanol , Femenino , Flumazenil/uso terapéutico , Isoniazida/toxicidad , Masculino , Ratones , Ratones Endogámicos ICR , Fitoterapia , Picrotoxina/toxicidad , Pilocarpina/toxicidad , Extractos Vegetales/aislamiento & purificación , Receptores de GABA-A/fisiología , Convulsiones/inducido químicamente , Solventes , Estricnina/toxicidad , AguaRESUMEN
Impairment in the energetic function of mitochondria is seen in many neurologic disorders like neurodegeneration. It disrupts ATP production, gives rise to oxidative stress, and ultimately challenges the viability of neurons. In this situation, neural cells use complex crosstalk between various subcellular elements to make live-or-die decisions about their fate. This study aimed to describe a part of the molecular changes and the outcome of the cellular decision during an energy crisis in neural cells in a time-dependent manner in the striatum. Adult male rats were treated with single or multiple 3-nitropropionic acid (3-NP) doses, a mitochondrial toxin, for 1 to 5 days. We found that protein disulfide isomerase (PDI) activity was decreased on the third day and remained lower than the control group up to the fifth day. However, on the day 1 and day 2 of 3-NP treatment, the stromal interaction molecule (STIM) 1 and STIM2 significantly decreased. On the third day, STIM1 and STIM2 were increased and reached the level of controls and remained the same up to the fifth day. In this condition, cell death was significantly higher than the controls from the third day up to the fifth day. We also showed that even a single dose of 3-NP reduced the brain volume. These data suggest that the STIM1, STIM2, and PDI activity changes may be involved in the outcome of cellular fate decisions. It also suggests that cells may reduce STIM1 and STIM2 as a defense mechanism against low energy availability.
Asunto(s)
Metabolismo Energético/efectos de los fármacos , Nitrocompuestos/toxicidad , Propionatos/toxicidad , Proteína Disulfuro Isomerasas/metabolismo , Transducción de Señal/efectos de los fármacos , Molécula de Interacción Estromal 1/metabolismo , Molécula de Interacción Estromal 2/metabolismo , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Convulsivantes/toxicidad , Retículo Endoplásmico/efectos de los fármacos , Retículo Endoplásmico/metabolismo , Metabolismo Energético/fisiología , Masculino , Tamaño de los Órganos/efectos de los fármacos , Tamaño de los Órganos/fisiología , Ratas , Ratas Wistar , Transducción de Señal/fisiologíaRESUMEN
OBJECTIVE: To confirm the critical factors affecting seizure susceptibility in acute pentylenetetrazole (PTZ) mouse epilepsy models and evaluate the prior literature for these factors. METHODS: Serial cohorts of wild-type mice administered intraperitoneal (IP)-PTZ were aggregated and analyzed by multivariate logistic regression for the effect of sex, age, background strain, dose, and physiologic stress (i.e., EEG implantation and/or single-housing) on seizure response. We assessed the reporting of these factors in a comprehensive literature review over the last 10 years (2010-2020). RESULTS: We conducted aggregated analysis of pooled data of 307 mice (220 C57BL/6J mice and 87 mixed background mice; 202 males, 105 females) with median age of 10 weeks (range: 6-49 weeks) with acute PTZ injection (dose range 40-65 mg/kg). Significance in multivariate analysis was found between seizures and increased PTZ dose (odds ratio (OR) 1.149, 95% confidence interval (CI) 1.102-1.205), older age (OR 1.1, 95% CI 1.041-1.170), physiologic stress (OR 17.36, 95% CI 7.349-44.48), and mixed background strain (OR 0.4725, 95% CI 0.2315-0.9345). Literature review identified 97 papers using acute PTZ-seizure models. Age, housing, sex, and background were omitted by 61% (59/97), 51% (49/97), 18% (17/97), and 8% (8/97) papers, respectively. Only 17% of publications specified all four factors (16/97). INTERPRETATION: Our analysis and literature review demonstrate a critical gap in standardization of acute PTZ-induced seizure paradigm in mice. We recommend that future studies specify and control for age, background strain, sex, and housing conditions of experimental animals.
Asunto(s)
Convulsivantes/toxicidad , Pentilenotetrazol/toxicidad , Convulsiones/inducido químicamente , Convulsiones/fisiopatología , Aislamiento Social , Factores de Edad , Animales , Electroencefalografía/métodos , Femenino , Masculino , Ratones , Ratones de la Cepa 129 , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Convulsiones/genética , Factores Sexuales , Especificidad de la EspecieRESUMEN
Early-life inflammatory stress increases seizure susceptibility later in life. However, possible sex- and age-specific differences and the associated mechanisms are largely unknown. C57BL/6 mice were bred in house, and female and male pups were injected with lipopolysaccharide (LPS; 100 µg/kg, i.p.) or vehicle control (saline solution) at postnatal day 14 (P14). Seizure threshold was assessed in response to pentylenetetrazol (1% solution, i.v.) in adolescence (â¼P40) and adulthood (â¼P60). We found that adult, but not adolescent, mice treated with LPS displayed â¼34% lower seizure threshold compared with controls. Females and males showed similar increased seizure susceptibility, suggesting that altered brain excitability was age dependent, but not sex dependent. Whole-cell recordings revealed no differences in excitatory synaptic activity onto CA1 pyramidal neurons from control or neonatally inflamed adolescent mice of either sex. However, adult mice of both sexes previously exposed to LPS displayed spontaneous EPSC frequency approximately twice that of controls, but amplitude was unchanged. Although these changes were not associated with alterations in dendritic spines or in the NMDA/AMPA receptor ratio, they were linked to an increased glutamate release probability from Schaffer collateral, but not temporoammonic pathway. This glutamate increase was associated with reduced activity of presynaptic GABAB receptors and was independent of the endocannabinoid-mediated suppression of excitation. Our new findings demonstrate that early-life inflammation leads to long-term increased hippocampal excitability in adult female and male mice associated with changes in glutamatergic synaptic transmission. These alterations may contribute to enhanced vulnerability of the brain to subsequent pathologic challenges such as epileptic seizures.SIGNIFICANCE STATEMENT Adult physiology has been shown to be affected by early-life inflammation. Our data reveal that early-life inflammation increases excitatory synaptic transmission onto hippocampal CA1 pyramidal neurons in an age-dependent manner through disrupted presynaptic GABAB receptor activity on Schaffer collaterals. This hyperexcitability was seen only in adult, and not in adolescent, animals of either sex. The data suggest a maturation process, independent of sex, in the priming action of early-life inflammation and highlight the importance of studying mature brains to reveal cellular changes associated with early-life interventions.
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Inflamación/fisiopatología , Células Piramidales/fisiología , Convulsiones/fisiopatología , Transmisión Sináptica/fisiología , Animales , Convulsivantes/toxicidad , Potenciales Postsinápticos Excitadores/fisiología , Femenino , Hipocampo/efectos de los fármacos , Hipocampo/fisiopatología , Inflamación/inducido químicamente , Lipopolisacáridos/toxicidad , Masculino , Ratones , Ratones Endogámicos C57BL , Pentilenotetrazol/toxicidad , Convulsiones/inducido químicamenteRESUMEN
With an associated 20% death risk, epilepsy mainly involves seizures of an unpredictable and recurrent nature. This study was designed to evaluate the neuroprotective effects and underlying mechanisms of insulin on mitochondrial disruption, oxidative stress, cell apoptosis and neurological deficits after epilepsy seizures. Mice were exposed to repetitive injections of pentylenetetrazol at a dose of 37 mg per kg. The influence of insulin was assessed by many biochemical assays, histopathological studies and neurobehavioral experiments. The administration of insulin was proven to increase the latency of seizures while also decreasing their intensity. It also caused a reversal of mitochondrial dysfunction and ameliorated oxidative stress. Additionally, insulin pretreatment upregulated Bcl-2, downregulated Bax, and then played a neuroprotective role against hippocampal neuron apoptosis. Furthermore, when insulin was administered, SIRT1/PGC-1α/SIRT3 signals were activated, possibly due to the fact that insulin's neuroprotective and anti-mitochondrial damage characteristics added to its observed antiepileptic functions. Finally, insulin treatment is thus extremely valuable for effecting improvements in neurological functions, as has been estimated in a series of functional tests. In conclude, the results of this study consequently demonstrate insulin to have significant potential for future application in epilepsy management.
Asunto(s)
Regulación de la Expresión Génica/efectos de los fármacos , Insulina/farmacología , Mitocondrias/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Estrés Oxidativo/efectos de los fármacos , Pentilenotetrazol/toxicidad , Convulsiones/tratamiento farmacológico , Animales , Convulsivantes/toxicidad , Hipoglucemiantes/administración & dosificación , Hipoglucemiantes/farmacología , Insulina/administración & dosificación , Masculino , Ratones , Mitocondrias/metabolismo , Mitocondrias/patología , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Convulsiones/inducido químicamente , Convulsiones/patología , Transducción de Señal , Sirtuina 1/genética , Sirtuina 1/metabolismo , Sirtuina 3/genética , Sirtuina 3/metabolismoRESUMEN
Neural precursor cell expressed developmentally down-regulated gene 4-like (NEDD4-2) encodes a ubiquitin E3 ligase that is involved in epileptogenesis with mechanisms needing further investigation. We constructed a novel Nedd4-2+/- mouse model with half level of both Nedd4-2 long and short isoforms in the brain. Nedd4-2 haploinsufficiency caused increased susceptibility and severity of pentylenetetrazole (PTZ)-induced seizures. Of the 3379 proteins identified by the hippocampal proteomic analysis, 55 were considered altered in Nedd4-2+/- mice compared with wild-type control, among which the inwardly rectifying K+ channel Kir4.1 was up-regulated by 1.83-fold. Kir4.1 was subsequently confirmed to be less ubiquitinated in response to comprised Nedd4-2 in mouse brains and C6 cells. Kir4.1 associated with Nedd4-2 through the threonine312-proline motif in the intracellular domain by target mutagenesis. Adaptor protein 14-3-3 facilitated Nedd4-2-mediated ubiquitination of Kir4.1. Our data consolidate the detailed molecular mechanism of Nedd4-2-mediated Kir4.1 ubiquitination, and provide a possible relationship between increased seizure susceptibility and impaired Kir4.1 ubiquitination in the brain.
Asunto(s)
Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Haploinsuficiencia , Ubiquitina-Proteína Ligasas Nedd4/fisiología , Canales de Potasio de Rectificación Interna/metabolismo , Proteoma/metabolismo , Convulsiones/etiología , Ubiquitinación , Animales , Convulsivantes/toxicidad , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Pentilenotetrazol/toxicidad , Canales de Potasio de Rectificación Interna/genética , Proteoma/análisis , Convulsiones/metabolismo , Convulsiones/patologíaRESUMEN
Epilepsy has been associated with several behavioral changes such as depression and anxiety while some antiepileptic drugs can precipitate psychiatric conditions in patients. This study evaluated the ameliorative effect of creatine on seizure severity and behavioral changes in pentylenetetrazole (PTZ) kindled mice. Mice were kindled by administering sub-convulsive doses of PTZ (35 mg/kg i.p.) at interval of 48 h. The naïve group (n = 7) constituted group 1, while successfully kindled mice were randomly assigned to five groups (n = 7). Group II served as vehicle treated group; groups III-V were treated with creatine 75, 150, and 300 mg/kg/day, p.o; Group V was given 25 mg/kg/day of phenytoin p.o. The treatment was for 15 consecutive days. The intensity of convulsion was scored according to a seven-point scale ranging from stage 0-7. Tail suspension test (TST) and Elevated plus maze (EPM) were utilized to assess depression and anxiety-like behavior respectively. After behavioral evaluation on day 15th, their brain was isolated and assayed for catalase, superoxide dismutase, reduced glutathione, and malondialdehyde. There was a significant (p < 0.05) reduction in the seizure scores, anxiety and depression-like behaviors in mice from the 5th day of treatment. The antioxidant assays revealed significant (p < 0.05) increase in catalase and reduced glutathione, and significant (p < 0.05) reduction in lipid peroxidation in treated mice. This study provides evidence for the seizure reducing property of creatine and its ameliorating potential on anxiety and depressive-like behaviors that follows seizure episodes.
Asunto(s)
Ansiedad/tratamiento farmacológico , Creatina/uso terapéutico , Depresión/tratamiento farmacológico , Pentilenotetrazol/toxicidad , Convulsiones/tratamiento farmacológico , Índice de Severidad de la Enfermedad , Animales , Ansiedad/inducido químicamente , Ansiedad/metabolismo , Convulsivantes/toxicidad , Creatina/farmacología , Depresión/inducido químicamente , Depresión/metabolismo , Relación Dosis-Respuesta a Droga , Glutatión/metabolismo , Peroxidación de Lípido/efectos de los fármacos , Peroxidación de Lípido/fisiología , Malondialdehído/metabolismo , Ratones , Convulsiones/inducido químicamente , Convulsiones/metabolismoRESUMEN
Epileptic seizures are the most common neurological diseases that change the function of neurovascular unit at molecular levels accompanied by activation of a wide variety of neurodegenerative cascades. Based on the pleiotropic functions of peroxisome proliferator-activated receptor-alpha (PPARα), the current study evaluated the neuroprotective effects of fenofibrate (an effective PPARα agonist) on the brain injuries induced by pentylenetetrazole (PTZ)-induced kindling seizure. Adult male NMRI mice were randomly assigned into four groups (n = 14) as follows; control, untreated kindled mice (PTZ) and two fenofibrate-treated kindled groups. Repeated intraperitoneal injections of PTZ (45 mg/kg) were used to develop kindling seizure every 48 h for 21 days. Treated mice were administered orally fenofibrate at doses of 30 and 50 mg/kg/day during the study. Plasma corticosterone and brain levels of brain-derived neurotrophic factor (BDNF), malondialdehyde (MDA) and mRNA transcription of p53, as well as blood-brain barrier (BBB) permeability, were determined at termination of the study. Fenofibrate considerably improved seizure latency and anxiety-like behaviors in treated kindled mice. Fenofibrate at doses of 30 and 50 mg/kg significantly (P < 0.001) decreased plasma corticosterone (56.88 ± 0.80 and 54.81 ± 0.29 ng/mL, respectively) compared to PTZ group (74.96 ± 1.60 ng/mL). It also significantly (P < 0.05) decreased BDNF levels in both treatment groups (8.13 ± 0.14 and 8.74 ± 0.09 ng/mL, respectively) compared to PTZ group (9.68 ± 0.20 ng/mL). Fenofibrate particularly at higher dose significantly (P < 0.01) decreased MDA content and mRNA expression levels of p53 in treated kindled mice by 67% and 28%, respectively, compared to PTZ group. Similarly, 50 mg/kg fenofibrate significantly (P < 0.05) decreased Evans blue extravasation into brain in treated kindled mice (8.72 ± 0.96 µg/g) compared to PTZ group (15.31 ± 2.18 µg/g). Our results revealed the anticonvulsive and neuroprotective effects of fenofibrate in PTZ-induced kindling seizure in mice. Fenofibrate also improved the neurovascular functions at molecular levels in kindling seizure that might be associated with ameliorating the seizure behaviors.
Asunto(s)
Encéfalo/efectos de los fármacos , Corticosterona/sangre , Fenofibrato/farmacología , Fármacos Neuroprotectores/farmacología , Convulsiones/fisiopatología , Animales , Anticonvulsivantes/farmacología , Barrera Hematoencefálica/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/fisiopatología , Factor Neurotrófico Derivado del Encéfalo/efectos de los fármacos , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Convulsivantes/toxicidad , Excitación Neurológica/efectos de los fármacos , Masculino , Ratones , Pentilenotetrazol/toxicidad , Distribución Aleatoria , Convulsiones/inducido químicamente , Convulsiones/metabolismoRESUMEN
Brain pH is thought to be important in epilepsy. The regulation of brain pH is, however, still poorly understood in animal models of chronic seizures (SZ) as well as in patients with intractable epilepsy. We used chemical exchange saturation transfer (CEST) MRI to noninvasively determine if the pH is alkaline shifted in a rodent model of the mesial temporal lobe (MTL) epilepsy with chronic SZ. Taking advantage of its high spatial resolution, we determined the pH values in specific brain regions believed to be important in this model produced by lithium-pilocarpine injection. All animals developed status epilepticus within 90 min after the lithium-pilocarpine administration, but one animal died within 24 hrs. All the surviving animals developed chronic SZ during the first 2 months. After SZ developed, brain pH was determined in the pilocarpine and control groups (n = 8 each). Epileptiform activity was documented in six pilocarpine rats with scalp EEG. The brain pH was estimated using two methods based on magnetization transfer asymmetry and amide proton transfer ratio. The pH was alkaline shifted in the pilocarpine rats (one outlier excluded) compared to the controls in the hippocampus (7.29 vs 7.17, t-test, p < 0.03) and the piriform cortex (7.34 vs. 7.06, p < 0.005), marginally more alkaline in the thalamus (7.13 vs. 7.01, p < 0.05), but not in the cerebral cortex (7.18 vs. 7.08, p > 0.05). Normalizing the brain pH may lead to an effective non-surgical method for treating intractable epilepsy as it is known that SZ can be eliminated by lowering the pH.
Asunto(s)
Química Encefálica/fisiología , Encéfalo/metabolismo , Epilepsia Refractaria/metabolismo , Epilepsia del Lóbulo Temporal/metabolismo , Concentración de Iones de Hidrógeno , Animales , Convulsivantes/toxicidad , Modelos Animales de Enfermedad , Cloruro de Litio/toxicidad , Masculino , Pilocarpina/toxicidad , Ratas , Ratas Sprague-DawleyRESUMEN
Increased neuronal expression of the Na-K-2Cl cotransporter NKCC1 has been implicated in the generation of seizures and epilepsy. However, conclusions from studies on the NKCC1-specific inhibitor, bumetanide, are equivocal, which is a consequence of the multiple potential cellular targets and poor brain penetration of this drug. Here, we used Nkcc1 knockout (KO) and wildtype (WT) littermate control mice to study the ictogenic and epileptogenic effects of intrahippocampal injection of kainate. Kainate (0.23 µg in 50 nl) induced limbic status epilepticus (SE) in both KO and WT mice with similar incidence, latency to SE onset, and SE duration, but the number of intermittent generalized convulsive seizures during SE was significantly higher in Nkcc1 KO mice, indicating increased SE severity. Following SE, spontaneous recurrent seizures (SRS) were recorded by continuous (24/7) video/EEG monitoring at 0-1, 4-5, and 12-13 weeks after kainate, using depth electrodes in the ipsilateral hippocampus. Latency to onset of electrographic SRS and the incidence of electrographic SRS were similar in WT and KO mice. However, the frequency of electrographic seizures was lower whereas the frequency of electroclinical seizures was higher in Nkcc1 KO mice, indicating a facilitated progression from electrographic to electroclinical seizures during chronic epilepsy, and a more severe epileptic phenotype, in the absence of NKCC1. The present findings suggest that NKCC1 is dispensable for the induction, progression and manifestation of epilepsy, and they do not support the widely held notion that inhibition of NKCC1 in the brain is a useful strategy for preventing or modifying epilepsy.
Asunto(s)
Epilepsia del Lóbulo Temporal/metabolismo , Miembro 2 de la Familia de Transportadores de Soluto 12/metabolismo , Animales , Convulsivantes/toxicidad , Modelos Animales de Enfermedad , Epilepsia del Lóbulo Temporal/inducido químicamente , Femenino , Ácido Kaínico/toxicidad , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , FenotipoRESUMEN
Ureases are microbial virulence factors either because of the enzymatic release of ammonia or due to many other non-enzymatic effects. Here we studied two neurotoxic urease isoforms, Canatoxin (CNTX) and Jack Bean Urease (JBU), produced by the plant Canavalia ensiformis, whose mechanisms of action remain elusive. The neurotoxins provoke convulsions in rodents (LD50 â¼2 mg/kg) and stimulate exocytosis in cell models, affecting intracellular calcium levels. Here, electrophysiological and brain imaging techniques were applied to elucidate their mode of action. While systemic administration of the toxins causes tonic-clonic seizures in rodents, JBU injected into rat hippocampus induced spike-wave discharges similar to absence-like seizures. JBU reduced the amplitude of compound action potential from mouse sciatic nerve in a tetrodotoxin-insensitive manner. Hippocampal slices from CNTX-injected animals or slices treated in vitro with JBU failed to induce long term potentiation upon tetanic stimulation. Rat cortical synaptosomes treated with JBU released L-glutamate. JBU increased the intracellular calcium levels and spontaneous firing rate in rat hippocampus neurons. MicroPET scans of CNTX-injected rats revealed increased [18]Fluoro-deoxyglucose uptake in epileptogenesis-related areas like hippocampus and thalamus. Curiously, CNTX did not affect voltage-gated sodium, calcium or potassium channels currents, neither did it interfere on cholinergic receptors, suggesting an indirect mode of action that could be related to the ureases' membrane-disturbing properties. Understanding the neurotoxic mode of action of C. ensiformis ureases could help to unveil the so far underappreciated relevance of these toxins in diseases caused by urease-producing microorganisms, in which the human central nervous system is affected.
Asunto(s)
Canavalia/química , Síndromes de Neurotoxicidad/etiología , Proteínas de Plantas/toxicidad , Toxinas Biológicas/toxicidad , Ureasa/toxicidad , Animales , Convulsivantes/aislamiento & purificación , Convulsivantes/toxicidad , Femenino , Masculino , Ratones , Sistema Nervioso/efectos de los fármacos , Sistema Nervioso/patología , Síndromes de Neurotoxicidad/fisiopatología , Proteínas de Plantas/aislamiento & purificación , Ratas , Ratas Wistar , Toxinas Biológicas/aislamiento & purificación , Ureasa/aislamiento & purificación , Xenopus laevisRESUMEN
There is a growing body of evidence demonstrating the significant involvement of the sigma-1 chaperone protein in the modulation of seizures. Several sigma-1 receptor (Sig1R) ligands have been demonstrated to regulate the seizure threshold in acute and chronic seizure models. However, the mechanism by which Sig1R modulates the excitatory and inhibitory pathways in the brain has not been elucidated. The aim of this study was to compare the susceptibility to seizures of wild type (WT) and Sig1R knockout (Sig1R-/-) mice in intravenous pentylenetetrazol (PTZ) and (+)-bicuculline (BIC) infusion-induced acute seizure and Sig1R antagonist NE-100-induced seizure models. To determine possible molecular mechanisms, we used quantitative PCR, Western blotting and immunohistochemistry to assess the possible involvement of several seizure-related genes and proteins. Peripheral tissue contractile response of WT and Sig1R-/- mice was studied in an isolated vasa deferentia model. The most important finding was the significantly decreased expression of the R2 subunit of the GABA-B receptor in the hippocampus and habenula of Sig1R-/- mice. Our results demonstrated that Sig1R-/- mice have decreased thresholds for PTZ- and BIC-induced tonic seizures. In the NE-100-induced seizure model, Sig1R-/- animals demonstrated lower seizure scores, shorter durations and increased latency times of seizures compared to WT mice. Sig1R-independent activities of NE-100 included downregulation of the gene expression of iNOS and GABA-A γ2 and inhibition of KCl-induced depolarization in both WT and Sig1R-/- animals. In conclusion, the results of this study indicate that the lack of Sig1R resulted in decreased expression of the R2 subunit of the GABA-B receptor and increased susceptibility to seizures. Our results confirm that Sig1R is a significant molecular target for seizure modulation and warrants further investigation for the development of novel anti-seizure drugs.
Asunto(s)
Convulsivantes/toxicidad , Habénula/metabolismo , Hipocampo/metabolismo , Receptores de GABA-B/genética , Receptores sigma/genética , Convulsiones/genética , Animales , Anisoles/toxicidad , Bicuculina/toxicidad , Expresión Génica/efectos de los fármacos , Expresión Génica/genética , Predisposición Genética a la Enfermedad , Habénula/efectos de los fármacos , Hipocampo/efectos de los fármacos , Ratones , Ratones Noqueados , Óxido Nítrico Sintasa de Tipo II/efectos de los fármacos , Óxido Nítrico Sintasa de Tipo II/genética , Pentilenotetrazol/toxicidad , Propilaminas/toxicidad , Receptores de GABA-A/efectos de los fármacos , Receptores de GABA-A/genética , Receptores de GABA-B/metabolismo , Convulsiones/inducido químicamente , Receptor Sigma-1RESUMEN
Since neonatal hypoxia-ischemia (HI) disrupts the hippocampal (Hp) GABAergic network in the mouse and Hp injury in this model correlates with flurothyl seizure susceptibility only in male mice, we hypothesized that GABAergic disruption correlates with flurothyl seizure susceptibility in a sex-specific manner. C57BL6 mice were exposed to HI (Vannucci model) versus sham procedures at P10, randomized to normothermia (NT) or therapeutic hypothermia (TH), and subsequently underwent flurothyl seizure testing at P18. Only in male mice, Hp atrophy correlated with seizure susceptibility. The number of Hp parvalbumin positive interneurons (PV+INs) decreased after HI in both sexes, but TH attenuated this deficit only in females. In males only, seizure susceptibility directly correlated with the number of PV+INs, but not somatostatin or calretinin expressing INs. Hp GABAB receptor subunit levels were decreased after HI, but unrelated to later seizure susceptibility. In contrast, Hp GABAA receptor α1 subunit (GABAARα1) levels were increased after HI. Adjusting the number of PV+ INs for their GABAARα1 expression strengthened the correlation with seizure susceptibility in male mice. Thus, we identified a novel Hp sex-specific GABA-mediated mechanism of compensation after HI that correlates with flurothyl seizure susceptibility warranting further study to better understand potential clinical translation.
Asunto(s)
Neuronas GABAérgicas/metabolismo , Hipocampo/metabolismo , Hipoxia-Isquemia Encefálica/metabolismo , Interneuronas/metabolismo , Animales , Animales Recién Nacidos , Convulsivantes/toxicidad , Susceptibilidad a Enfermedades , Flurotilo/toxicidad , Neuronas GABAérgicas/fisiología , Hipocampo/fisiopatología , Hipoxia-Isquemia Encefálica/fisiopatología , Interneuronas/fisiología , Ratones , Parvalbúminas , Convulsiones/inducido químicamente , Factores SexualesRESUMEN
Nitric oxide (NO) is known to be a neuromodulator with dual proconvulsive and anticonvul- sive action. Valeriana officinalis (VAL) was previously believed to be antiepileptic, but is today known as a sedative and sleep regulator. Seizures may be associated with abnormal electrocardio- graphic changes and cardiac dysfunction arising from epilepsy may be related with neuronal nitric oxide (nNO). This study was aimed to investigate the effects of the neuronal nitric oxide synthase (nNOS) inhibitor 7-Nitroindazole (7-NI) and VAL on seizure behaviours and electrocar- diographic parameters in the pentylentetrazole (PTZ)-kindled seizure model. Wistar rats were randomised into saline control, PTZ-kindled, 7-NI, VAL and VAL+PTZ, 7-NI+PTZ and VAL+7-NI+PTZ groups. Latency, stage, frequency of seizures, blood pressure (BP), heart rate (HR) and corrected QT (QTc) values were evaluated. Frequency and stage of seizures, BP and HR increased, while seizure latency decreased and QTc was prolonged in the PTZ-kindled group. 7-NI and VAL had no effects on BP and HR variables under normal conditions, but ameliorated the seizure stage and frequency of seizures. 7-NI treatment also resulted in a reduction of the increased BP and prolonged QTc values observed in PTZ-kindled rats. Considering these results, QTc prolongation may be used as a predictor for recurrent seizures. 7-NI and VAL exhibited different effects on seizures and ECG variables. 7-NI shows potential as an anticonvulsant drug agent in epileptic patients with cardiac dysfunctions and those additional studies including in-vivo experiments are essential.