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Introduction: The gut microbiota and the microbiota-gut-brain axis have gained considerable attention in recent years, emerging as key players in the mechanisms that mediate the occurrence and progression of many central nervous system-related diseases, including epilepsy. In clinical practice, one of the side effects of quinolone antibiotics is a lower seizure threshold or aggravation. However, the underlying mechanism remains unclear. Methods: We aimed to unravel the intrinsic mechanisms through 16S rRNA sequencing and serum untargeted metabolomic analysis to shed light on the effects of gut microbiota in ciprofloxacin-induced seizure susceptibility and lithium pilocarpine-induced epilepsy rat models. Results: We observed that ciprofloxacin treatment increased seizure susceptibility and caused gut dysbiosis. We also found similar changes in the gut microbiota of rats with lithium pilocarpine-induced epilepsy. Notably, the levels of Akkermansia and Bacteroides significantly increased in both the ciprofloxacin-induced seizure susceptibility and lithium pilocarpine-induced epilepsy rat models. However, Marvinbryantia, Oscillibacter, and Ruminococcaceae_NK4A214_group showed a coincidental reduction. Additionally, the serum untargeted metabolomic analysis revealed decreased levels of indole-3-propionic acid, a product of tryptophan-indole metabolism, after ciprofloxacin treatment, similar to those in the plasma of lithium pilocarpine-induced epilepsy in rats. Importantly, alterations in the gut microbiota, seizure susceptibility, and indole-3-propionic acid levels can be restored by fecal microbiota transplantation. Conclusion: In summary, our findings provide evidence that ciprofloxacin-induced seizure susceptibility is partially mediated by the gut microbiota and tryptophan-indole metabolism. These associations may play a role in epileptogenesis, and impacting the development progression and treatment outcomes of epilepsy. [ABSTRACT FROM AUTHOR]

Pathogenic missense mutation of the FGF12 gene is responsible for a variable disease phenotypic spectrum. Disease-specific therapies require precise dissection of the relationship between different mutations and phenotypes. The lack of a proper animal model hinders the investigation of related diseases, such as early-onset epileptic encephalopathy. Here, an FGF12AV52H mouse model was generated using CRISPR/Cas9 technology, which altered the A isoform without affecting the B isoform. The FGF12AV52H mice exhibited seizure susceptibility, while no spontaneous seizures were observed. The increased excitability in dorsal hippocampal CA3 neurons was confirmed by patch-clamp recordings. Furthermore, immunostaining showed that the balance of excitatory/inhibitory neurons in the hippocampus of the FGF12AV52H mice was perturbed. The increases in inhibitory SOM+ neurons and excitatory CaMKII+ neurons were heterogeneous. Moreover, the locomotion, anxiety levels, risk assessment behavior, social behavior, and cognition of the FGF12AV52H mice were investigated by elevated plus maze, open field, three-chamber sociability, and novel object tests, respectively. Cognition deficit, impaired risk assessment, and social behavior with normal social indexes were observed, implying complex consequences of V52H FGF12A in mice. Together, these data suggest that the function of FGF12A in neurons can be immediate or long-term and involves modulation of ion channels and the differentiation and maturation of neurons. The FGF12AV52H mouse model increases the understanding of the function of FGF12A, and it is of great importance for revealing the complex network of the FGF12 gene in physiological and pathological processes.

Patients with mutations that alter the function of the sodium channel SCN8A present with a range of clinical features, including mild to severe seizures, developmental delay, intellectual disability, autism, feeding dysfunction, motor impairment, and hypotonia. In an effort to identify compounds that could be potentially beneficial in SCN8A-associated epilepsy, Atkin et al. conducted an in vitro screen which resulted in the identification of 90 compounds that effectively reduced sodium influx into the cells expressing the human SCN8A R1872Q mutation. The top compounds that emerged from this screen included amitriptyline, carvedilol, and nilvadipine. In the current study, we evaluated the ability of these three compounds to increase resistance to 6 Hz or pentylenetetrazole (PTZ)-induced seizures in wild-type CF1 mice and in a mouse line expressing the human SCN8A R1620L mutation. We also evaluated the effects of fenfluramine administration, which was recently associated with a 60%–90% decrease in seizure frequency in three patients with SCN8Aassociated epilepsy. While amitriptyline, carvedilol, and fenfluramine provided robust protection against induced seizures in CF1 mice, only carvedilol was able to significantly increase resistance to 6 Hz- and PTZ-induced seizures in RL/+ mutants. These results provide support for further evaluation of carvedilol as a potential treatment for patients with SCN8A mutations. [ABSTRACT FROM AUTHOR]

The intricate relationship between viruses and epilepsy involves a bidirectional interaction. Certain viruses can induce epilepsy by infecting the brain, leading to inflammation, damage, or abnormal electrical activity. Conversely, epilepsy patients may be more susceptible to viral infections due to factors, such as compromised immune systems, anticonvulsant drugs, or surgical interventions. Neuroinflammation, a common factor in both scenarios, exhibits onset, duration, intensity, and consequence variations. It can modulate epileptogenesis, increase seizure susceptibility, and impact anticonvulsant drug pharmacokinetics, immune system function, and brain physiology. Viral infections significantly impact the clinical management of epilepsy patients, necessitating a multidisciplinary approach encompassing diagnosis, prevention, and treatment of both conditions. We delved into the dual dynamics of viruses inducing epilepsy and epilepsy patients acquiring viruses, examining the unique features of each case. For virus-induced epilepsy, we specify virus types, elucidate mechanisms of epilepsy induction, emphasize neuroinflammation's impact, and analyze its effects on anticonvulsant drug pharmacokinetics. Conversely, in epilepsy patients acquiring viruses, we detail the acquired virus, its interaction with existing epilepsy, neuroinflammation effects, and changes in anticonvulsant drug pharmacokinetics. Understanding this interplay advances precision therapies for epilepsy during viral infections, providing mechanistic insights, identifying biomarkers and therapeutic targets, and supporting optimized dosing regimens. However, further studies are crucial to validate tools, discover new biomarkers and therapeutic targets, and evaluate targeted therapy safety and efficacy in diverse epilepsy and viral infection scenarios. [ABSTRACT FROM AUTHOR]

Genetic abnormalities affecting glutamate receptors are central to excitatory overload-driven neuronal mechanisms that culminate in seizures, making them pivotal targets in epilepsy research. Increasingly used to advance this field, the genetically audiogenic seizure hamster from Salamanca (GASH/Sal) exhibits generalized seizures triggered by high-intensity acoustic stimulation and harbors significant genetic variants recently identified through whole-exome sequencing. Here, we addressed the influence of the missense single-nucleotide polymorphism (C9586732T, p.His289Tyr) in the glutamate receptor ionotropic kainate-1 (Grikl) gene and its implications for the GASH/Sal seizure susceptibility. Using a protein 3D structure prediction, we showed a potential effect of this sequence variation, located in the amino-terminal domain, on the stability and/or conformation of the kainate receptor subunit-1 protein (GluK1). We further employed a multi-technique approach, encompassing gene expression analysis (RT-qPCR), Western blotting, and immunohistochemistry in bright-field and confocal fluorescence microscopy, to investigate critical seizure-associated brain regions in GASH/Sal animals under seizure-free conditions compared to matched wild-type controls. We detected disruptions in the transcriptional profile of the Grikl gene within the audiogenic seizure-associated neuronal network. Alterations in GluK1 protein levels were also observed in various brain structures, accompanied by an unexpected lower molecular weight band in the inferior and superior colliculi. This correlated with substantial disparities in GluK1-immunolabeling distribution across multiple brain regions, including the cerebellum, hippocampus, subdivisions of the inferior and superior colliculi, and the prefrontal cortex. Notably, the diffuse immunolabeling accumulated within perikarya, axonal fibers and terminals, exhibiting a prominent concentration in proximity to the cell nucleus. This suggests potential disturbances in the GluK1-trafficking mechanism, which could subsequently affect glutamate synaptic transmission. Overall, our study sheds light on the genetic underpinnings of seizures and underscores the importance of investigating the molecular mechanisms behind synaptic dysfunction in epileptic neural networks, laying a crucial foundation for future research and therapeutic strategies targeting GluKi-containing kainate receptors. [ABSTRACT FROM AUTHOR]

Patients with mutations that alter the function of the sodium channel SCN8A present with a range of clinical features, including mild to severe seizures, developmental delay, intellectual disability, autism, feeding dysfunction, motor impairment, and hypotonia. In an effort to identify compounds that could be potentially beneficial in SCN8A-associated epilepsy, Atkin et al. conducted an in vitro screen which resulted in the identification of 90 compounds that effectively reduced sodium influx into the cells expressing the human SCN8A R1872Q mutation. The top compounds that emerged from this screen included amitriptyline, carvedilol, and nilvadipine. In the current study, we evaluated the ability of these three compounds to increase resistance to 6 Hz or pentylenetetrazole (PTZ)-induced seizures in wild-type CF1 mice and in a mouse line expressing the human SCN8A R1620L mutation. We also evaluated the effects of fenfluramine administration, which was recently associated with a 60%–90% decrease in seizure frequency in three patients with SCN8A-associated epilepsy. While amitriptyline, carvedilol, and fenfluramine provided robust protection against induced seizures in CF1 mice, only carvedilol was able to significantly increase resistance to 6 Hz- and PTZ-induced seizures in RL/+ mutants. These results provide support for further evaluation of carvedilol as a potential treatment for patients with SCN8A mutations.

Pathogenic missense mutation of the FGF12 gene is responsible for a variable disease phenotypic spectrum. Disease-specific therapies require precise dissection of the relationship between different mutations and phenotypes. The lack of a proper animal model hinders the investigation of related diseases, such as early-onset epileptic encephalopathy. Here, an FGF12AV52H mouse model was generated using CRISPR/Cas9 technology, which altered the A isoform without affecting the B isoform. The FGF12AV52H mice exhibited seizure susceptibility, while no spontaneous seizures were observed. The increased excitability in dorsal hippocampal CA3 neurons was confirmed by patch-clamp recordings. Furthermore, immunostaining showed that the balance of excitatory/inhibitory neurons in the hippocampus of the FGF12AV52H mice was perturbed. The increases in inhibitory SOM+ neurons and excitatory CaMKII+ neurons were heterogeneous. Moreover, the locomotion, anxiety levels, risk assessment behavior, social behavior, and cognition of the FGF12AV52H mice were investigated by elevated plus maze, open field, three-chamber sociability, and novel object tests, respectively. Cognition deficit, impaired risk assessment, and social behavior with normal social indexes were observed, implying complex consequences of V52H FGF12A in mice. Together, these data suggest that the function of FGF12A in neurons can be immediate or long-term and involves modulation of ion channels and the differentiation and maturation of neurons. The FGF12AV52H mouse model increases the understanding of the function of FGF12A, and it is of great importance for revealing the complex network of the FGF12 gene in physiological and pathological processes. • FGF12AV52H mice exhibit susceptibility to seizures. • FGF12AV52H mutation alters the excitability of neurons in hippocampus. • Behavioral phenotyping shows cognitive deficit and impaired risk assessment in FGF12AV52H mice. [ABSTRACT FROM AUTHOR]

Abstract Background Systemic inflammation is a potent contributor to increased seizure susceptibility. However, information regarding the effects of systemic inflammation on cerebral vascular integrity that influence neuron excitability is scarce. Necroptosis is closely associated with inflammation in various neurological diseases. In this study, necroptosis was hypothesized to be involved in the mechanism underlying sepsis-associated neuronal excitability in the cerebrovascular components (e.g., endothelia cells). Methods Lipopolysaccharide (LPS) was used to induce systemic inflammation. Kainic acid intraperitoneal injection was used to measure the susceptibility of the mice to seizure. The pharmacological inhibitors C87 and GSK872 were used to block the signaling of TNFα receptors and necroptosis. In order to determine the features of the sepsis-associated response in the cerebral vasculature and CNS, brain tissues of mice were obtained for assays of the necroptosis-related protein expression, and for immunofluorescence staining to identify morphological changes in the endothelia and glia. In addition, microdialysis assay was used to assess the changes in extracellular potassium and glutamate levels in the brain. Results Some noteworthy findings, such as increased seizure susceptibility and brain endothelial necroptosis, Kir4.1 dysfunction, and microglia activation were observed in mice following LPS injection. C87 treatment, a TNFα receptor inhibitor, showed considerable attenuation of increased kainic acid-induced seizure susceptibility, endothelial cell necroptosis, microglia activation and restoration of Kir4.1 protein expression in LPS-treated mice. Treatment with GSK872, a RIP3 inhibitor, such as C87, showed similar effects on these changes following LPS injection. Conclusions The findings of this study showed that TNFα-mediated necroptosis induced cerebrovascular endothelial damage, neuroinflammation and astrocyte Kir4.1 dysregulation, which may coalesce to contribute to the increased seizure susceptibility in LPS-treated mice. Pharmacologic inhibition targeting this necroptosis pathway may provide a promising therapeutic approach to the reduction of sepsis-associated brain endothelia cell injury, astrocyte ion channel dysfunction, and subsequent neuronal excitability.

Chronic hypobaric hypoxia in high‐altitude areas is closely related to the occurrence of many neurological diseases. Among these diseases, epilepsy is a common disease of the nervous system that is difficult to diagnose and treat, with a long treatment cycle. As of 2019, there were more than 70 million epilepsy patients worldwide, including 10 million in China. Studies have shown that chronic hypoxia promotes the occurrence and development of epilepsy, and elucidation of the relationship between chronic hypoxia and epilepsy is important for studying the pathogenesis of epilepsy and exploring the potential characteristics of epilepsy and new drug targets for epilepsy. In this article, we review the factors that may cause increased seizure susceptibility in chronic hypoxia and consider the potential relationship between chronic hypobaric hypoxia and seizure susceptibility in high‐altitude areas and prospects surrounding related research in the future. [ABSTRACT FROM AUTHOR]

Brain aging is characterized by a gradual decline in cellular homeostatic processes, thereby losing the ability to respond to physiological stress. At the anatomical level, the aged brain is characterized by degenerating neurons, proteinaceous plaques and tangles, intracellular deposition of glycogen, and elevated neuroinflammation. Intriguingly, such age-associated changes are also seen in neurodegenerative disorders suggesting that an accelerated aging process could be one of the contributory factors for the disease phenotype. Amongst these, the genetic forms of progressive myoclonus epilepsy (PME), resulting from loss-of-function mutations in genes, manifest symptoms that are common to age-associated disorders, and genes mutated in PME are involved in the cellular homeostatic processes. Intriguingly, the incidence and/or onset of epileptic seizures are known to increase with age, suggesting that physiological changes in the aged brain might contribute to increased susceptibility to seizures. We, therefore, hypothesized that the expression level of genes implicated in PME might decrease with age, thereby leading to a compromised neuronal response towards physiological stress and hence neuroinflammation in the aging brain. Using mice models, we demonstrate here that the expression level of PME genes shows an inverse correlation with age, neuroinflammation, and compromised heat shock response. We further show that the pharmacological suppression of neuroinflammation ameliorates seizure susceptibility in aged animals as well as in animal models for a PME. Taken together, our results indicate a functional role for the PME genes in normal brain aging and that neuroinflammation could be a major contributory player in susceptibility to seizures. [ABSTRACT FROM AUTHOR]

Background: Systemic inflammation is a potent contributor to increased seizure susceptibility. However, information regarding the effects of systemic inflammation on cerebral vascular integrity that influence neuron excitability is scarce. Necroptosis is closely associated with inflammation in various neurological diseases. In this study, necroptosis was hypothesized to be involved in the mechanism underlying sepsis-associated neuronal excitability in the cerebrovascular components (e.g., endothelia cells).Methods: Lipopolysaccharide (LPS) was used to induce systemic inflammation. Kainic acid intraperitoneal injection was used to measure the susceptibility of the mice to seizure. The pharmacological inhibitors C87 and GSK872 were used to block the signaling of TNFα receptors and necroptosis. In order to determine the features of the sepsis-associated response in the cerebral vasculature and CNS, brain tissues of mice were obtained for assays of the necroptosis-related protein expression, and for immunofluorescence staining to identify morphological changes in the endothelia and glia. In addition, microdialysis assay was used to assess the changes in extracellular potassium and glutamate levels in the brain.Results: Some noteworthy findings, such as increased seizure susceptibility and brain endothelial necroptosis, Kir4.1 dysfunction, and microglia activation were observed in mice following LPS injection. C87 treatment, a TNFα receptor inhibitor, showed considerable attenuation of increased kainic acid-induced seizure susceptibility, endothelial cell necroptosis, microglia activation and restoration of Kir4.1 protein expression in LPS-treated mice. Treatment with GSK872, a RIP3 inhibitor, such as C87, showed similar effects on these changes following LPS injection.Conclusions: The findings of this study showed that TNFα-mediated necroptosis induced cerebrovascular endothelial damage, neuroinflammation and astrocyte Kir4.1 dysregulation, which may coalesce to contribute to the increased seizure susceptibility in LPS-treated mice. Pharmacologic inhibition targeting this necroptosis pathway may provide a promising therapeutic approach to the reduction of sepsis-associated brain endothelia cell injury, astrocyte ion channel dysfunction, and subsequent neuronal excitability. [ABSTRACT FROM AUTHOR]

Abstract The Ihara epileptic rat (IER) is a mutant model with limbic-like seizures whose pathology and causative gene remain elusive. In this report, via linkage analysis, we identified Down syndrome cell adhesion molecule-like 1(Dscaml1) as the responsible gene for IER. A single base mutation in Dscaml1 causes abnormal splicing, leading to lack of DSCAML1. IERs have enhanced seizure susceptibility and accelerated kindling establishment. Furthermore, GABAergic neurons are severely reduced in the entorhinal cortex (ECx) of these animals. Voltage-sensitive dye imaging that directly presents the excitation status of brain slices revealed abnormally persistent excitability in IER ECx. This suggests that reduced GABAergic neurons may cause weak sustained entorhinal cortex activations, leading to natural kindling via the perforant path that could cause dentate gyrus hypertrophy and epileptogenesis. Furthermore, we identified a single nucleotide substitution in a human epilepsy that would result in one amino acid change in DSCAML1 (A2105T mutation). The mutant DSCAML1A2105T protein is not presented on the cell surface, losing its homophilic cell adhesion ability. We generated knock-in mice (Dscaml1 A2105T ) carrying the corresponding mutation and observed reduced GABAergic neurons in the ECx as well as spike-and-wave electrocorticogram. We conclude that DSCAML1 is required for GABAergic neuron placement in the ECx and suppression of seizure susceptibility in rodents. Our findings suggest that mutations in DSCAML1 may affect seizure susceptibility in humans.

Background: Clinical and pre-clinical studies indicate a reduction in seizure frequency as well as a decrease in susceptibility to subsequently evoked seizures after physical exercise programs. In contrast to the influence of exercise after epilepsy previously established, various studies have been conducted attempting to investigate whether physical activity reduces brain susceptibility to seizures or prevents epilepsy. We report a systematic review and meta-analysis of different animal models that addressed the impact of previous physical exercise programs to reduce seizure susceptibility. Methods: We included animal model (rats and mice) studies before brain insult that reported physical exercise programs compared with other interventions (sham, control, or naïve). We excluded studies that investigated animal models after brain insult, associated with supplement nutrition or drugs, that did not address epilepsy or seizure susceptibility, ex vivo studies, in vitro studies, studies in humans, or in silico studies. Electronic searches were performed in the MEDLINE (PubMed), Web of Science (WOS), Scopus, PsycINFO, Scientific Electronic Library Online (SciELO) databases, and gray literature, without restrictions to the year or language of publication. We used SYRCLE's risk of bias tool and CAMARADES checklist for study quality. We performed a synthesis of results for different types of exercise and susceptibility to seizures by random-effects meta-analysis. Results: Fifteen studies were included in the final analysis (543 animals), 13 of them used male animals, and Wistar rats were the most commonly studied species used in the studies (355 animals). The chemoconvulsants used in the selected studies were pentylenetetrazol, penicillin, kainic acid, pilocarpine, and homocysteine. We assessed the impact of study design characteristics and the reporting of mitigations to reduce the risk of bias. We calculated a standardized mean difference effect size for each comparison and performed a random-effects meta-analysis. The meta-analysis included behavioral analysis (latency to seizure onset, n = 6 and intensity of motor signals, n = 3) and electrophysiological analysis (spikes/min, n = 4, and amplitude, n = 6). The overall effect size observed in physical exercise compared to controls for latency to seizure onset was −130.98 [95% CI: −203.47, −58.49] (seconds) and the intensity of motor signals was −0.40 [95% CI: −1.19, 0.40] (on a scale from 0 to 5). The largest effects were observed in electrophysiological analysis for spikes/min with −26.96 [95% CI: −39.56, −14.36], and for spike amplitude (μV) with −282.64 [95% CI: −466.81, −98.47]. Discussion: Limitations of evidence. A higher number of animal models should be employed for analyzing the influence of exerciseon seizure susceptibility. The high heterogeneity in our meta-analysis is attributable to various factors, including the number of animals used in each study and the limited number of similar studies. Interpretation. Studies selected in this systematic review and meta-analysis suggest that previous physical exercise programs can reduce some of the main features related to seizure susceptibility [latency seizure onset, spikes/min, and spike amplitude (μV)] induced by the administration of different chemoconvulsants. Systematic Review Registration: PROSPERO, identifier CRD42021251949; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=251949. [ABSTRACT FROM AUTHOR]

Background: Clinical and pre-clinical studies indicate a reduction in seizure frequency as well as a decrease in susceptibility to subsequently evoked seizures after physical exercise programs. In contrast to the influence of exercise after epilepsy previously established, various studies have been conducted attempting to investigate whether physical activity reduces brain susceptibility to seizures or prevents epilepsy. We report a systematic review and meta-analysis of different animal models that addressed the impact of previous physical exercise programs to reduce seizure susceptibility.Methods: We included animal model (rats and mice) studies before brain insult that reported physical exercise programs compared with other interventions (sham, control, or naïve). We excluded studies that investigated animal models after brain insult, associated with supplement nutrition or drugs, that did not address epilepsy or seizure susceptibility, ex vivo studies, in vitro studies, studies in humans, or in silico studies. Electronic searches were performed in the MEDLINE (PubMed), Web of Science (WOS), Scopus, PsycINFO, Scientific Electronic Library Online (SciELO) databases, and gray literature, without restrictions to the year or language of publication. We used SYRCLE's risk of bias tool and CAMARADES checklist for study quality. We performed a synthesis of results for different types of exercise and susceptibility to seizures by random-effects meta-analysis.Results: Fifteen studies were included in the final analysis (543 animals), 13 of them used male animals, and Wistar rats were the most commonly studied species used in the studies (355 animals). The chemoconvulsants used in the selected studies were pentylenetetrazol, penicillin, kainic acid, pilocarpine, and homocysteine. We assessed the impact of study design characteristics and the reporting of mitigations to reduce the risk of bias. We calculated a standardized mean difference effect size for each comparison and performed a random-effects meta-analysis. The meta-analysis included behavioral analysis (latency to seizure onset, n = 6 and intensity of motor signals, n = 3) and electrophysiological analysis (spikes/min, n = 4, and amplitude, n = 6). The overall effect size observed in physical exercise compared to controls for latency to seizure onset was −130.98 [95% CI: −203.47, −58.49] (seconds) and the intensity of motor signals was −0.40 [95% CI: −1.19, 0.40] (on a scale from 0 to 5). The largest effects were observed in electrophysiological analysis for spikes/min with −26.96 [95% CI: −39.56, −14.36], and for spike amplitude (μV) with −282.64 [95% CI: −466.81, −98.47].Discussion:Limitations of evidence. A higher number of animal models should be employed for analyzing the influence of exerciseon seizure susceptibility. The high heterogeneity in our meta-analysis is attributable to various factors, including the number of animals used in each study and the limited number of similar studies. Interpretation. Studies selected in this systematic review and meta-analysis suggest that previous physical exercise programs can reduce some of the main features related to seizure susceptibility [latency seizure onset, spikes/min, and spike amplitude (μV)] induced by the administration of different chemoconvulsants.Systematic Review Registration: PROSPERO, identifier CRD42021251949; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=251949.

We report the case of a patient with severe progressive epilepsy and peripheral neuropathy and a novel de novo inactivating variant (p.E79X) in Protein Kinase D1 (PKD1). Using CRISPR/Cas9, we engineered the homologous variant in mice and showed that in the homozygote mouse, it recapitulated the patient peripheral nerve hypermyelination pathology. The lethality of the homozygote mouse prevented us from performing an assessment of locomotor behavior. The mutant heterozygote mouse; however, exhibited a significant increase in kainate‐induced seizure activity over wild‐type mice, supporting the hypothesis that the PKD1 variant is a candidate for the cause of the patient epilepsy. Because PKD1 was previously identified in a kinomic screen as an interacting partner of the K‐Cl cotransporter 3 (KCC3), and since KCC3 is involved in peripheral nerve disease and brain hyperexcitability, one possible mechanism of action of PKD1 in disease is through KCC3. We show that catalytically inactive PKD1 stimulates KCC3 activity, consistent with tonic relief of inhibitory phosphorylation. Our findings implicate a novel role for PKD1 in the human nervous system, and uncover a mechanism that could serve as a potential target to promote nervous system myelination. [ABSTRACT FROM AUTHOR]

The metalloproteinase ADAM10 is the most important amyloid precursor protein (APP) α-secretase, preventing the deposit of neurotoxic amyloid β (Aβ) peptide and generating a soluble APP fragment (sAPP α) with neurotrophic functions. Recent studies have suggested that ADAM10 also play a role in the pathogenesis of inflammatory CNS diseases, such as multiple sclerosis (MS). Demyelination is the hallmarks of MS but the mechanisms involved remain unclear. Here in this study, we examined the role that ADAM10 might play in the cuprizone-induced demyelination model. Our results demonstrated that ADAM10 expression and sAPP α production were significantly reduced in the corpus callosum in response to cuprizone treatment. Overexpression of ADAM10 increased sAPP α production and suppressed demyelination as well as neuroinflammation and oxidative stress in cuprizone-induced demyelination model. Pharmacological inhibition of ADAM10 activity, however, abrogates the protective effect of ADAM10 against demyelination, neuroinflammation and oxidative stress. It has been reported that CNS demyelination may induce seizure activity. Here, we found that overexpression of ADAM10 reduced seizure susceptibility in cuprizone-induced demyelination model, suggesting that ADAM10-derived sAPP α suppresses demyelination and reduces seizure susceptibility via ameliorating neuroinflammation and oxidative stress in cuprizone-induced demyelination model. [Display omitted] • ADAM10 expression is reduced in cupizone-induced demyelination. • ADAM10 protects against cupizone-induced myelin structural protein loss. • ADAM10 suppresses CPZ-induced mature oligodendrocytes loss and oligodendrocyte progenitor cells proliferation. • Inhibition of ADAM10 abrogates the protective effect of ADAM10 against demyelination and oxidative stress. • ADAM10 suppresses CPZ-induced seizure susceptibility. [ABSTRACT FROM AUTHOR]

A large body of data has confirmed that α7 nicotinic acetylcholine receptors (nAChRs) play a pivotal role in cognition, memory, and other neuropsychiatric diseases, but their effect on seizure susceptibility in C57BL/6 wild-type mice is not fully understood. Here, we showed that decreased activity of α7 nAChRs could increase the excitability of CA1 pyramidal neurons and shorten the onset time of epilepsy in pilocarpine-induced mouse models. However, compared with the control group, there was no apparent effect of increasing the activity of α7 nAChRs. Moreover, the expression of α7 nAChRs is downregulated in human epileptogenic tissues. Taken together, our findings indicate that α7 nAChR is an essential regulator of seizure susceptibility.

Background: Oxidative stress is thought to be closely related to epileptogenesis. We have previously reported that nitric oxide (NO) levels are higher in epilepsy-prone EL mice between the ages of 3 and 8 weeks than in control mice. However, NO is divided into two fractions, nitrite (NO2) and nitrate (NO3), which appear to play different roles in epileptogenesis. Methods: NO2 and NO3 levels were measured, in EL mice and the control mice, in the parietal cortex, which is thought to be the primary epileptogenetic center in EL mice, and measured in the hippocampus, which is thought to be the secondary center. Results: NO3 levels in the hippocampus and parietal cortex of the immature EL mice (3 to 8 weeks of age) were significantly higher than those in the control mice; NO2 levels were significantly higher in the EL mice throughout the study period. The NO3 levels were significantly higher than the NO2 levels in the immature EL mice, but after the onset of ictogenesis at 10 weeks of age, the relative levels of the two fractions reversed. Conclusion: The reversal of the NO fraction distribution at the onset of seizures that we observed may be related to the developmental process of seizure susceptibility in the neural network of EL mice. [ABSTRACT FROM AUTHOR]

A large body of data has confirmed that α7 nicotinic acetylcholine receptors (nAChRs) play a pivotal role in cognition, memory, and other neuropsychiatric diseases, but their effect on seizure susceptibility in C57BL/6 wild-type mice is not fully understood. Here, we showed that decreased activity of α7 nAChRs could increase the excitability of CA1 pyramidal neurons and shorten the onset time of epilepsy in pilocarpine-induced mouse models. However, compared with the control group, there was no apparent effect of increasing the activity of α7 nAChRs. Moreover, the expression of α7 nAChRs is downregulated in human epileptogenic tissues. Taken together, our findings indicate that α7 nAChR is an essential regulator of seizure susceptibility. [ABSTRACT FROM AUTHOR]

Epilepsy is one of the main clinical problems in Angelman syndrome (AS). Seizures typically start in early childhood then decrease or are often alleviated by young adulthood. Several studies using AS model mice showed comparable seizure susceptibility during young adulthood. In contrast, the course of epilepsy post young adulthood differs from persistently relieved to rerising among reports. To elucidate this, we evaluated the seizure susceptibility of AS model mice of two different ages. Mice lacking maternal Ube3a gene (Ube3a m–/p+) of C57BL/6 background or their littermate wild type (WT) were divided into two groups by age, 2 to 3 months (2–3 M) and 6 to 12 months (6–12 M), corresponding to adolescent to young adult aged and middle aged humans, respectively. Seizure susceptibility was evaluated by flurothyl inhalation or intraperitoneal injection of pentylenetetrazole (PTZ IP)-induced acute seizure protocol. In the flurothyl-induced seizure paradigm, the latency to seizure occurrence had a significant interaction with genotype and age. Post-hoc analysis revealed that the latency was significantly shorter at 6–12 M than at 2–3 M in Ube3a m-/p+ mice, and in Ube3a m-/p+ mice than in WT mice at 6–12 M. No significant interaction or difference was observed by PTZ IP. The flurothyl-induced seizure paradigm revealed that seizure susceptibility of Ube3a m-/p+ mice increased with age, similar to clinical studies reporting the reappearance of epilepsy in older age. The flurothyl-induced seizure paradigm applied to middle-aged Ube3a m–/p+ mice could be a suitable protocol for screening drugs against seizures in AS. [ABSTRACT FROM AUTHOR]

• Elevated Nmnat2 causes damage to CA1 neurons and lowers the onset threshold. • Elevated Nmnat2 reduces the expression levels of anti-oxidative proteins. • Molecular chaperone function is involved in the damage mediated by Nmnat2. • Abnormally expressed Nmnat2 affects the activation of signal pathways related to cell survival. A significant pathological feature of refractory temporal lobe epilepsy (TLE) is neuronal loss. Oxidative stress caused by repeated seizures is an important mechanism leading to neuronal loss in hippocampus. Nicotinamide-adenine dinucleotide (NAD) a coenzyme that is involved in many biochemical oxidation-reduction reactions. Nicotinamide mononucleotide adenylyltransferase 2 (Nmnat2) catalyzes an essential step in NAD (NADP) biosynthetic pathwayhas and been considered as a neuronal maintenance factor that protect neurons against insults through context-dependent mechanism. However, it is unexpected that Nmnat2 does not play a neuroprotective role in epilepsy. We found that Nmnat2 was increased in mice model of TLE. Gain-of-function approach revealed that overexpression of Nmnat2 in CA1 area enhanced seizure susceptibility and caused neuronal loss in vivo. Moreover, we found that the chaperone function was essential to increased apoptosis through the function mutation of Nmnat2. Finally, Nmnat2 overexpression in vivo reduced in expression of SOD2 and increased FoxO3a. Overall, our study discloses a new biological function of Nmnat2 in epilepsy and provides novel insights into the molecular events underlying epilepsy. [ABSTRACT FROM AUTHOR]

Introduction: The gut microbiota and the microbiota-gut-brain axis have gained considerable attention in recent years, emerging as key players in the mechanisms that mediate the occurrence and progression of many central nervous system-related diseases, including epilepsy. In clinical practice, one of the side effects of quinolone antibiotics is a lower seizure threshold or aggravation. However, the underlying mechanism remains unclear., Methods: We aimed to unravel the intrinsic mechanisms through 16S rRNA sequencing and serum untargeted metabolomic analysis to shed light on the effects of gut microbiota in ciprofloxacin-induced seizure susceptibility and lithium pilocarpine-induced epilepsy rat models., Results: We observed that ciprofloxacin treatment increased seizure susceptibility and caused gut dysbiosis. We also found similar changes in the gut microbiota of rats with lithium pilocarpine-induced epilepsy. Notably, the levels of Akkermansia and Bacteroides significantly increased in both the ciprofloxacin-induced seizure susceptibility and lithium pilocarpine-induced epilepsy rat models. However, Marvinbryantia, Oscillibacter , and Ruminococcaceae_NK4A214_group showed a coincidental reduction. Additionally, the serum untargeted metabolomic analysis revealed decreased levels of indole-3-propionic acid, a product of tryptophan-indole metabolism, after ciprofloxacin treatment, similar to those in the plasma of lithium pilocarpine-induced epilepsy in rats. Importantly, alterations in the gut microbiota, seizure susceptibility, and indole-3-propionic acid levels can be restored by fecal microbiota transplantation., Conclusion: In summary, our findings provide evidence that ciprofloxacin-induced seizure susceptibility is partially mediated by the gut microbiota and tryptophan-indole metabolism. These associations may play a role in epileptogenesis, and impacting the development progression and treatment outcomes of epilepsy., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Zou, Li, Zou, Yang, Li, Niu, Lai, Wang, Yang and Zhou.)

Neuregulin 1 (NRG1)–induced activation of ErbB4 in parvalbumin (PV) inhibitory interneurons is reported to serve as a critical endogenous negative-feedback mechanism to repress brain epileptogenesis. Here, we investigated the seizure susceptibility and the role of NRG1-ErbB4 signaling in PV interneurons in the suppression of epileptic seizures for rats subject to early life hypoxia. Neonatal postnatal day 5 (P5) rats were exposed to intermittent hypoxia (IH) or control (CON) room air for 10 days. In the prefrontal cortex (PFC) of P54 rats, we determined the impact of neonatal IH exposures on the expression of PV, NRG1, ErbB4, and phosphorylated ErbB4 (p-ErbB4) during the seizure induction. Seizure susceptibility tests with the common convulsant agent pentylenetetrazole (PEN) at P54 revealed that rats subject to neonatal hypoxia exposure developed faster and more serious epileptic seizures. Neonatal IH exposures (1) decreased the number of PV cells in the PFC of P54 rats; (2) interrupted the expression of NRG1 gene; and (3) altered the activity of NRG1 on PV interneurons in the PFC after the seizure induction. Intracerebroventricular delivery of exogenous NRG1 before seizure induction by PEN significantly reduced the seizure susceptibility for neonatal IH-exposed rats. The ErbB4 inhibitor AG1478 inhibited the exogenous NRG1's effects on seizure susceptibility. Environmental enrichment (EE) rescued the abovementioned pathophysiological alterations and significantly attenuated the epileptic seizures after the seizure induction for neonatal IH-exposed rats. Our study indicated early life hypoxia exposure might increase the seizure susceptibility for rats and contribute to pathophysiological dysfunction of NRG1-ErbB4 signaling in PV interneurons in the suppression of epileptic seizures. EE might attenuate the increased seizure susceptibility for neonatal IH-exposed rats through rescuing pathophysiological alterations of NRG1-ErbB4 signaling in PV interneurons. [ABSTRACT FROM AUTHOR]

Objective: Animal studies remain essential for understanding mechanisms of epilepsy and identifying new therapeutic targets. However, existing animal models of epilepsy do not reflect the high level of genetic diversity found in the human population. The Collaborative Cross (CC) population is a genetically diverse recombinant inbred panel of mice. The CC offers large genotypic and phenotypic diversity, inbred strains with stable genomes that allow for repeated phenotypic measurements, and genomic tools including whole genome sequence to identify candidate genes and candidate variants. Methods: We evaluated multiple complex epileptic traits in a sampling of 35 CC inbred strains using the flurothyl‐induced seizure and kindling paradigm. We created an F2 population of 297 mice with extreme seizure susceptibility and performed quantitative trait loci (QTL) mapping to identify genomic regions associated with seizure sensitivity. We used quantitative RNA sequencing from CC hippocampal tissue to identify candidate genes and whole genome sequence to identify genetic variants likely affecting gene expression. Results: We identified new mouse models with extreme seizure susceptibility, seizure propagation, epileptogenesis, and SUDEP (sudden unexpected death in epilepsy). We performed QTL mapping and identified one known and seven novel loci associated with seizure sensitivity. We combined whole genome sequencing and hippocampal gene expression to pinpoint biologically plausible candidate genes (eg, Gabra2) and variants associated with seizure sensitivity. Significance: New mouse models of epilepsy are needed to better understand the complex genetic architecture of seizures and to identify therapeutics. We performed a phenotypic screen utilizing a novel genetic reference population of CC mice. The data we provide enable the identification of protective/risk genes and novel molecular mechanisms linked to complex seizure traits that are currently challenging to study and treat. [ABSTRACT FROM AUTHOR]

Carbon black nanoparticles (CBNPs) can enter the central nervous system through blood circulation and olfactory nerves, affecting brain development or increasing neurological disease susceptibility. However, whether CBNPs exposure affects seizure is unclear. Herein, mice were exposed to two different doses of CBNPs (21 and 103 μg/animal) based on previous studies and the maximum exposure limitation (4 mg/m3) in occupational workplaces set by the Chinese government. In the pentylenetetrazol (PTZ) and kainic acid (KA) seizure models, high-dose CBNPs exposure increased seizure susceptibility in both models and increased spontaneous recurrent seizure (SRS) frequency in the KA model. In vivo local field potential (LFP) recording in KA model mice revealed that both low-dose and high-dose CBNPs exposure increased seizure-like event (SLE) frequency in the SRS interval but shortened SLE duration. Intriguingly, H&E staining and Nissl staining on brain tissue revealed that CBNPs exposure did not cause significant brain tissue morphology or neuronal damage. Detection of inflammatory factors, such as TNF-α, TGF-β1, IL-1β, and IL-6, in brain tissue showed that only high dose of CBNPs exposure increased the expression of cortical TGF-β1. By using the primary cultured neurons, we observed that CBNPs exposure not only significantly decreased the expression of the neuronal marker MAP2 but also enhanced the levels of action potential frequency in the neurons. In general, CBNPs exposure can affect abnormal epileptic discharges during the seizure interval and enhance susceptibility to frequent seizures. Our findings suggest that minimizing CBNPs exposure may be a potential way to prevent or ease seizure. [ABSTRACT FROM AUTHOR]

• REST/NRSF act to confer a neuroprotection against seizure. • TrkB play a pivotal role during epileptogenesis. • Modulation of REST/NRSF-TrkB may be potential target to prevent epileptogenesis. Global transcriptional disturbances are believed to play a major role in the course of epilepsy. Due to the high complexity, the neurobiological mechanisms underlying different susceptibility to seizure and epilepsy are not well known. A transcription factor called REST/NRSF (repressor element 1-silencing transcription factor/neuron-restrictive silencer factor) is believed to contribute to processes associated with seizure development. Its downstream genes, those encoding BDNF (brain-derived neurotrophic factor) and TrkB (BDNF receptor; tropomyosin receptor kinase B), are also thought to play a role. To verify this hypothesis, we used a PTZ kindling model of epilepsy and divided animals into groups according to their different susceptibility to seizure. The concentrations of REST/NRSF, BDNF, and TrkB protein and mRNA were measured in hippocampal homogenates. The level of REST/NRSF protein measured 24 h after the last PTZ injection was increased in animals resistant to kindling and was unchanged in groups of rats kindled after 5, 10 and 20 in.ections of PTZ. In contrast, TrkB protein concentration was enhanced in all kindled rats and was unchanged in the resistant rats. There were no changes in the protein concentration of BDNF in rats with different susceptibility to kindling; however, data from the combined kindled groups vs. the resistant group revealed an increased level of BDNF in resistant animals. In sum, the increased level of protein REST/NRSF in resistant animals may reflect its neuroprotective role against seizure development. The increased concentration of TrkB protein in kindled animals indicates its pivotal role in the process of epileptogenesis. We propose that in resistant rats, REST/NRSF could contribute to the prevention of TrkB activation related to seizures. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) carries a risk of developing post-traumatic epilepsy (PTE). Currently, animal models that replicate clinical PTE (delayed spontaneous and recurrent seizures) are limited, which hinders pre-clinical research. In this study, we used two rat models of penetrating ballistic-like brain injury (PBBI) and closed-head injury (CHI) to induce spontaneous seizures and also measure changes in seizure susceptibility. In the PBBI model, two trajectories (frontal and lateral) and two injury severities for each trajectory, were evaluated. In the CHI model, a single projectile impact to the dorsal/lateral region of the head was tested. Continuous video-electroencephalographic (EEG) recordings were collected for 10 days at 1 or 6 month(s) post-injury. After EEG recording, all rats were given a sub-convulsant dose of pentylenetetrazole (PTZ) to challenge the seizure susceptibility. The video-EEG recording did not detect PTE following the PBBI. Only one CHI rat demonstrated persistent and recurrent non-convulsive seizures detected at 6 months post-injury. However, after PTZ challenge, 50–100% of the animals across different TBI groups experienced seizures. Seizure susceptibility increased over time from 1 to 6 months post-injury across the majority of TBI groups. Injury severity effects were not apparent within the PBBI model, but were evident between PBBI and CHI models. These results demonstrated the difficulties in detecting delayed spontaneous post-traumatic seizures even in a high-risk model of penetrating brain injury. The PTZ-induced increase in seizure susceptibility indicated the existence of vulnerable risk of epileptogenesis following TBI, which may be considered as an alternative research tool for pre-clinical studies of PTE. [ABSTRACT FROM AUTHOR]

Alterations in white matter integrity have been well documented in chronic epilepsy and during epileptogenesis. However, the relationship between white matter integrity and a predisposition towards epileptogenesis has been understudied. The FAST rat strain exhibit heightened susceptibility towards kindling epileptogenesis whereas SLOW rats are highly resistant. FAST rats also display behavioral phenotypes reminiscent of those observed in neurodevelopmental disorders that commonly comorbid with epilepsy. In this study, we aim to identify differences in white matter integrity that may contribute to a predisposition towards epileptogenesis and its associated comorbidities in 6 month old FAST (n = 10) and SLOW (n = 10) male rats. Open field and water consumption tests were conducted to confirm the behavioral phenotype difference between FAST and SLOW rats followed by ex-vivo diffusion-weighted magnetic resonance imaging to identify differences in white matter integrity. Diffusion tensor imaging scalar values namely fractional anisotropy, mean diffusivity, axial diffusivity and radial diffusivity were compared in the anterior commissure, corpus callosum, external capsule, internal capsule, fimbria and optic tract. Electron microscopy was used to evaluate microstructural alterations in myelinated axons. Behavioral phenotyping confirmed higher activity levels (distance moved on days 2–4, p

Mutations in voltage-gated sodium channels expressed highly in the brain (SCN1A, SCN2A, SCN3A, and SCN8A) are responsible for an increasing number of epilepsy syndromes. In particular, mutations in the SCN3A gene, encoding the pore-forming Nav1.3 α subunit, have been identified in patients with focal epilepsy. Biophysical characterization of epilepsy-associated SCN3A variants suggests that both gain- and loss-of-function SCN3A mutations may lead to increased seizure susceptibility. In this report, we identified a novel SCN3A variant (L247P) by whole exome sequencing of a child with focal epilepsy, developmental delay, and autonomic nervous system dysfunction. Voltage clamp analysis showed no detectable sodium current in a heterologous expression system expressing the SCN3A-L247P variant. Furthermore, cell surface biotinylation demonstrated a reduction in the amount of SCN3A-L247P at the cell surface, suggesting the SCN3A-L247P variant is a trafficking-deficient mutant. To further explore the possible clinical consequences of reduced SCN3A activity, we investigated the effect of a hypomorphic Scn3a allele (Scn3aHyp) on seizure susceptibility and behavior using a gene trap mouse line. Heterozygous Scn3a mutant mice (Scn3a+/Hyp) did not exhibit spontaneous seizures nor were they susceptible to hyperthermia-induced seizures. However, they displayed increased susceptibility to electroconvulsive (6 Hz) and chemiconvulsive (flurothyl and kainic acid) induced seizures. Scn3a+/Hyp mice also exhibited deficits in locomotor activity and motor learning. Taken together, these results provide evidence that loss-of-function of SCN3A caused by reduced protein expression or deficient trafficking to the plasma membrane may contribute to increased seizure susceptibility.

Environmental exposure early in development plays a role in susceptibility to disease in later life. Here, we demonstrate that prolonged febrile seizures induced by exposure of rat pups to a hyperthermic environment enhance seizure susceptibility not only in these hyperthermia-treated rats but also in their future offspring, even if the offspring never experience febrile seizures. This transgenerational transmission was intensity-dependent and was mainly from mothers to their offspring. The transmission was associated with DNA methylation. Thus, our study supports a “Lamarckian”-like mechanism of pathogenesis and the crucial role of epigenetic factors in neurological conditions.

Objective: The endocannabinoid system (ECS) is comprised of cannabinoid receptors 1 and 2 (CB1R and CB2R), endogenous ligands, and regulatory enzymes, and serves to regulate several important physiological functions throughout the brain and body. Recent evidence suggests that the ECS may be a promising target for the treatment of epilepsy, including epilepsy subtypes that arise from mutations in the voltage‐gated sodium channel SCN1A. The objective of this study was to explore the effects of modulating CB2R activity on seizure susceptibility. Methods: We examined susceptibility to induced seizures using a number of paradigms in CB2R knockout mice (Cnr2−/−), and determined the effects of the CB2R agonist, JWH‐133, and the CB2R antagonist, SR144528, on seizure susceptibility in wild‐type mice. We also examined seizure susceptibility in Cnr2 mutants harboring the human SCN1A R1648H (RH) epilepsy mutation and performed Electroencephalography (EEG) analysis to determine whether the loss of CB2Rs would increase spontaneous seizure frequency in Scn1a RH mutant mice. Results: Both heterozygous (Cnr2+/−) and homozygous (Cnr2−/−) knockout mice exhibited increased susceptibility to pentylenetetrazole (PTZ)‐induced seizures. The CB2R agonist JWH‐133 did not significantly alter seizure susceptibility in wild‐type mice; however, administration of the CB2R antagonist SR144528 resulted in increased susceptibility to PTZ‐induced seizures. In offspring from a cross between the Cnr2 × RH lines, both Cnr2 and RH mutants were susceptible to PTZ‐induced seizures; however, seizure susceptibility was not significantly increased in mutants expressing both mutations. No spontaneous seizures were observed in either RH or Cnr2/RH mutants during 336‐504 hours of continuous EEG recordings. Significance: Our results demonstrate that reduced CB2R activity is associated with increased seizure susceptibility. CB2Rs might therefore provide a therapeutic target for the treatment of some forms of epilepsy. [ABSTRACT FROM AUTHOR]

Shank3, a postsynaptic scaffolding protein involved in regulating excitatory synapse assembly and function, has been implicated in several brain disorders, including autism spectrum disorders (ASD), Phelan-McDermid syndrome, schizophrenia, intellectual disability, and mania. Here we generated and characterized a Shank3 knock-in mouse line carrying the Q321R mutation (Shank3 Q321R mice) identified in a human individual with ASD that affects the ankyrin repeat region (ARR) domain of the Shank3 protein. Homozygous Shank3 Q321R/Q321R mice show a selective decrease in the level of Shank3a, an ARR-containing protein variant, but not other variants. CA1 pyramidal neurons in the Shank3 Q321R/Q321R hippocampus show decreased neuronal excitability but normal excitatory and inhibitory synaptic transmission. Behaviorally, Shank3 Q321R/Q321R mice show moderately enhanced self-grooming and anxiolytic-like behavior, but normal locomotion, social interaction, and object recognition and contextual fear memory. In addition, these mice show abnormal electroencephalogram (EEG) patterns and decreased susceptibility to induced seizures. These results indicate that the Q321R mutation alters Shank3 protein stability, neuronal excitability, repetitive and anxiety-like behavior, EEG patterns, and seizure susceptibility in mice. [ABSTRACT FROM AUTHOR]

Highlights • Plau and Plaur dKO mice are susceptible to PTZ-induced seizures. • Plau and Plaur dKO mice are more social than Wt mice. • dKO mice have normal number of perineuronal nets in the cerebral cortex. Abstract Extracellular proteolysis initiated by the binding of urokinase-type plasminogen activator (uPA) to its receptor (uPAR) regulates the development of inhibitory neuronal circuits in the cerebral cortex and tissue remodeling after epileptogenic brain injury. To study the function of different components of the uPA-uPAR system on behavior and epileptogenesis, and to complement our previous studies on naïve and injured mice deficient in the uPA-encoding gene Plau or the uPAR-encoding gene Plaur , we analyzed the behavioral phenotype, seizure susceptibility, and perineuronal nets surrounding parvalbumin-positive inhibitory interneurons in Plau and Plaur (double knockout dKO) mice. In a climbing test, dKO mice showed reduced interest towards the environment as compared with Wt mice (p < 0.01). In a social approach test, however, dKO mice spent more time than Wt mice exploring the compartment containing a stranger mouse than the empty compartment (p < 0.05). Moreover, in a social interaction test, dKO mice exhibited increased contact time (p < 0.01). Compared with Wt mice, the dKO mice also had a longer single contact duration (p < 0.001) with the stranger mouse. In the elevated plus-maze, grooming, and marble burying tests, the anxiety level of dKO mice did not differ from that of Wt mice. Rearing time in an exploratory activity test, and spatial learning and memory in the Morris swim navigation task were also comparable between dKO and Wt mice. In the pentylenetetrazol (PTZ) seizure-susceptibility test, dKO mice had a shorter latency to the first epileptiform spike (p = 0.0001) and a greater total number of spikes (p < 0.001) than Wt mice. The dKO genotype did not affect the number of cortical perineuronal nets. Our findings indicate that Plau/Plaur -deficiency leads to a more social phenotype toward other mice with diminished interest in the surrounding environment, and increased seizure susceptibility. [ABSTRACT FROM AUTHOR]

• SHR exhibit lower anxiety in the NSFT compared to Wistar rats. • WKY rats has a decreased spontaneous activity than Wistar rats in the active phase. • Spatial working and associative memory is impaired in SHR compared to Wistar rats. • WKY rats has higher susceptibility for RMA than Wistar and SHR. • The hippocampal BDNF is related to the level of brain excitability in Wistar and WKY rats. Spontaneously hypertensive rats (SHRs) are widely accepted for modeling essential hypertension and Attention deficit hyperactivity disorder (ADHD). However, data concerning central nervous system changes associated with behavioral responses of this strain and usage of Wistar Kyoto (WKY) rats as controls are confounding. The objective of the present study was to assess the impact of anxiety and motor activity on the cognitive responses of SHRs compared to Wistar and WKY rats. In addition, the role of brain-derived neurotrophic factor (BDNF) in the hippocampus on cognitive behavior and seizure susceptibility in the three strains was evaluated. In Experiment#1 , SHR demonstrated impulsive responses in the novelty suppression feeding test accompanied by impaired spatial working and associative memory in the Y maze and object recognition test compared with the Wistar rat but not WKY rats. In addition, the WKY rats exhibited diminished activity compared to Wistar rats in an actimeter. In Experiment#2 , the seizure susceptibility was assessed by 3-min electroencephalographic (EEG) recording after two consecutive injections of pentylenetetrazol (PTZ) (20+40 mg/kg). The WKY rats were more vulnerable to rhythmic metrazol activity (RMA) than the Wistar rats. In contrast, Wistar rats were more prone to generalized tonic-clonic seizures (GTCS) than WKY rats and SHRs. Control SHR had lower BDNF expression in the hippocampus compared to Wistar rats. However, while the BDNF levels were elevated in the Wistar and WKY rats after PTZ injection, no change in this signaling molecule was observed in the SHR in the seizure condition. The results suggest Wistar rats as a more appropriate control of SHR than WKY rats for studying memory responses mediated by BDNF in the hippocampus. The higher vulnerability to seizures in Wistar and WKY rats compared to SHR might be linked to PTZ-induced decreased expression of BDNF in the hippocampus. [ABSTRACT FROM AUTHOR]

Atypical febrile seizures are considered a risk factor for epilepsy onset and cognitive impairments later in life. Patients with temporal lobe epilepsy and a history of atypical febrile seizures often carry a cortical malformation. This association has led to the hypothesis that the presence of a cortical dysplasia exacerbates febrile seizures in infancy, in turn increasing the risk for neurological sequelae. The mechanisms linking these events are currently poorly understood. Potassium-chloride cotransporter KCC2 affects several aspects of neuronal circuit development and function, by modulating GABAergic transmission and excitatory synapse formation. Recent data suggest that KCC2 downregulation contributes to seizure generation in the epileptic adult brain, but its role in the developing brain is still controversial.In a rodent model of atypical febrile seizures, combining a cortical dysplasia and hyperthermia-induced seizures (LHS rats), we found a premature and sustained increase in KCC2 protein levels, accompanied by a negative shift of the reversal potential of GABA. In parallel, we observed a significant reduction in dendritic spine size and mEPSC amplitude in CA1 pyramidal neurons, accompanied by spatial memory deficits. To investigate whether KCC2 premature overexpression plays a role in seizure susceptibility and synaptic alterations, we reduced KCC2 expression selectively in hippocampal pyramidal neurons by in utero electroporation of shRNA. Remarkably, KCC2 shRNA-electroporated LHS rats show reduced hyperthermia-induced seizure susceptibility, while dendritic spine size deficits were rescued. Our findings demonstrate that KCC2 overexpression in a compromised developing brain increases febrile seizure susceptibility and contribute to dendritic spine alterations.

Hypoxic-ischemic encephalopathy is a common neonatal brain injury associated with significant morbidity and mortality despite the administration of therapeutic hypothermia (TH). Neonatal seizures and subsequent chronic epilepsy are frequent in this patient population and current treatments are partially effective. We used a neonatal murine hypoxia-ischemia (HI) model to test whether the severity of hippocampal and cortical injury predicts seizure susceptibility 8 days after HI and whether TH mitigates this susceptibility. HI at postnatal day 10 (P10) caused hippocampal injury not mitigated by TH in male or female pups. TH did not confer protection against flurothyl seizure susceptibility at P18 in this model. Hippocampal (R2 = 0.33, p = 0.001) and cortical (R2 = 0.33, p = 0.003) injury directly correlated with seizure susceptibility in male but not female pups. Thus, there are sex-specific consequences of neonatal HI on flurothyl seizure susceptibility in a murine neonatal HI model. Further studies are necessary to elucidate the underlying mechanisms of sex dimorphism in seizure susceptibility after neonatal HI. [ABSTRACT FROM AUTHOR]

Cortical dysplasia is the most common etiology of intractable epilepsy. Both excitability changes in cortical neurons and neural network reconstitution play a role in cortical dysplasia epileptogenesis. Recent research shows that the axon initial segment, a subcompartment of the neuron important to the shaping of action potentials, adjusts its position in response to changes in input, which contributes to neuronal excitability and local circuit balance. It is unknown whether axon initial segment plasticity occurs in neurons involved in seizure susceptibility in cortical dysplasia. Here, we developed a “Carmustine”- “pilocarpine” rat model of cortical dysplasia and show that it exhibits a lower seizure threshold, as indicated by behavior studies and electroencephalogram monitoring. Using immunofluorescence, we measured the axon initial segment positions of deep L5 somatosensory neurons and show that it is positioned closer to the soma after acute seizure, and that this displacement is sustained in the chronic phase. We then show that Nifedipine has a dose-dependent protective effect against axon initial segment displacement and increased seizure susceptibility. These findings further our understanding of the pathophysiology of seizures in cortical dysplasia and suggests Nifedipine as a potential therapeutic agent. [ABSTRACT FROM AUTHOR]

Summary: Objective: Aberrant myelination and developmental delay have been reported in epilepsy. However, it is unclear whether these are linked to intrinsic mechanisms that support a predisposition toward seizures and the development of epilepsy. Thus, we compared rates of myelination and neurodevelopment in male rats selectively bred for enhanced susceptibility to kindling epileptogenesis (FAST) with male rats bred for resistance (SLOW). Methods: Myelin‐specific gene expression was compared in the brainstem, cerebellum, and cerebral hemisphere of FAST and SLOW rats on postnatal days (PNDs) 5, 11, 17, 23, and 90 to determine strain‐specific myelination rates. Myelin protein levels were also compared at PNDs 5 and 23 in the brainstem. Relative rates of neurodevelopment were evaluated between PNDs 5 and 21 using physical growth landmarks and neuromotor tests including righting reflex, cliff avoidance, negative geotaxis, and locomotor activity. Results: Myelin‐specific mRNA expression was significantly down‐regulated in FAST rats on PNDs 5 and 11 in all 3 brain structures, indicating relatively delayed myelination. Likewise, corresponding protein levels were significantly lower in FAST brainstem on PND 5. Developmental delay was evident in the FAST strain such that only 9% of FAST pups, compared to 81% of SLOW, had open eyes by PND 13, locomotor activity was significantly reduced between PNDs 12 and 16, and neuromotor task acquisition was delayed between PNDs 5 and 10. Significance: Relative delays in myelination and neurodevelopment co‐occurred in the seizure‐prone FAST strain in the absence of seizures. These findings suggest these symptoms are not seizure‐induced and may be mechanistically linked to an underlying pathophysiology supporting a predisposition toward developing epilepsy. [ABSTRACT FROM AUTHOR]

Objective The appropriate use of analgesic drugs based on their degree of analgesia and adverse effects is important for pain management. Although it has been reported that AM404, a metabolite of acetaminophen, has anticonvulsant effects in several animal seizure models, little is known about the relation between acetaminophen and seizures. We therefore investigated the effects of acetaminophen on seizure susceptibility in several mouse seizure and epilepsy models and compared the effects with those of nonsteroidal anti-inflammatory drugs (NSAIDs). Methods Anticonvulsant activity was evaluated in ICR mice using maximum electroshock-induced seizure tests and acute pentylenetetrazol-induced seizure tests. Electrical kindling via corneal stimulation and pentylenetetrazol administration were used to establish animal kindling epilepsy models. Proconvulsive activity was examined using an electroconvulsive shock test with low-stimulus currents. Results Acetaminophen showed slight, but not statistically significant, anticonvulsant activity in both the maximum electroshock-induced seizure test (300–600 mg/kg i.p.) and acute pentylenetetrazol-induced seizure test (100–600 mg/kg i.p.). In contrast, acetaminophen exhibited significant anticonvulsant effects in corneal electroshock-kindled and pentylenetetrazol-kindled mice (ED 50 values: 251 and 310 mg/kg i.p., respectively). When the proconvulsive effects of NSAIDs were examined in the low-current electroconvulsive shock-induced seizure model, the nonselective cyclooxygenase (COX)-1 and COX-2 inhibitors indomethacin, diclofenac, and loxoprofen induced dose-dependent proconvulsant activity. Celecoxib, a COX-2 selective inhibitor, had no proconvulsant activity. Conclusion These findings suggest that acetaminophen has a significant anticonvulsant effect and that its profile is completely different from that of NSAIDs. [ABSTRACT FROM AUTHOR]

A growing body of evidence suggests that stress triggers a variety of pathophysiological responses. Recent studies show that stress produces enduring effects on structure and function of hippocampus, which is one of the most important structures involved in epilepsy. In the present study, we determined the effect of repeated restraint stress exposure on the susceptibility of pentylenetetrazole (PTZ)-induced seizures and the possible mechanisms involved using a rodent model. Our results show that mice subjected to repeated restraint stress exhibited shorter latency to PTZ-induced tonic-clonic seizures and higher seizure severity, suggesting chronic restraint stress increases seizure susceptibility. Following repeated restraint stress, we observed an increased level of endoplasmic reticulum (ER) stress as well as oxidative stress in the hippocampus. Moreover, our results show that chronic restraint stress exposure causes neuron loss in the hippocampus. Inhibition of ER stress with chemical chaperone, tauroursodeoxycholic acid (TUDCA), however, protects against chronic restraint stress-induced neuron loss, suggesting repeated restraint stress-induced neuronal degeneration is dependent on ER stress activation. On the other hand, inhibition of ER stress with TUDCA suppresses restraint stress-induced seizure susceptibility. Taken together, these results indicate that repeated restraint stress increases seizure susceptibility by activation of hippocampal ER stress and ER stress mediated oxidative stress and neurodegeneration. Thus, attenuating ER stress may serve as a potential therapeutic strategy targeted to block stress-induced seizure activities. [ABSTRACT FROM AUTHOR]