Model Of Epilepsy Research Articles

Circulating microRNAs and isomiRs as biomarkers for the initial insult and epileptogenesis in four experimental epilepsy models: The EPITARGET study.

Structural epilepsies can manifest months or years after the occurrence of an initial epileptogenic insult, making them amenable for secondary prevention. However, development of preventive treatments has been challenged by a lack of biomarkers for identifying the subset of individuals with the highest risk of epilepsy after the epileptogenic insult. Four different rat models of epileptogenesis were investigated to identify differentially expressed circulating microRNA (miRNA) and isomiR profiles as biomarkers for epileptogenesis. Plasma samples were collected on day 2 and day 9 during the latency period from animals that did or did not develop epilepsy during long-term video-electroencephalographic monitoring. miRNAs and isomiRs were identified and measured in an unsupervised manner, using a genome-wide small RNA sequencing platform. Receiver operating characteristic analysis was performed to determine the performance of putative biomarkers. Two days after an epileptogenic insult, alterations in the levels of several plasma miRNAs and isomiRs predicted epileptogenesis in a model-specific manner. One miRNA, miR-3085, showed good sensitivity (but low specificity) as a prognostic biomarker for epileptogenesis in all four models (area under the curve = .729, sensitivity = 83%, specificity = 64%, p < .05). Identified plasma miRNAs and isomiRs are mostly etiology-specific rather than common prognostic biomarkers of epileptogenesis. These data imply that in preclinical and clinical studies, it may be necessary to identify specific biomarkers for different epilepsy etiologies. Importantly, circulating miRNAs like miR-3085 with high negative predictive value for epileptogenesis in different etiologies could be useful candidates for initial screening purposes of epileptogenesis risk.

YTHDF1 gene inhibits epilepsy progression by epigenetic activation of PTEN gene

Epilepsy is a common chronic neurological disorder with high prevalence that profoundly affects millions of people worldwide. Inflammatory dysregulation affects central nervous system disorders including epilepsy, and YTHDF1, the most common "reader" of m6A and m6A-binding protein, can attenuate the inflammatory response and activate PTEN, and here we aimed to investigate its effect on epilepsy through epigenetics. All mice were injected intraperitoneally with 12 mg/kg of sea manic acid to establish an epilepsy model, and the epileptic behaviors of the mice were classified into 6 grades; epileptic behaviors of grade 3 or above were defined as seizures, and consecutive epileptic seizures of more than 30 min were considered as successful modeling. Mouse behavior was examined using the Morris Water Maze tracking assay; inflammatory factors IL-6, TNF-α, and IL-1β were detected by qPCR/WB/ELISA; cell activity was analyzed by CCK-8; apoptotic markers were identified by immunofluorescence assay and Western blot analysis. YTHDF1 knockout mice have poor spatial memory capacity and sensitivity to external stimuli. Under the influence of YTHDF1, the neuroinflammation and nseuron death decreased. YTHDF1 works by repressing the production of pro-inflammatory cytokines and the activation of astrocytes. It was found that YTHDF1 epigenetically activates PTEN through m6A modification, activates glial cells and represses pro-inflammatory cytokines production and inhibits the development of epilepsy.

Overexpression of BDNF Suppresses the Epileptiform Activity in Cortical Neurons of Heterozygous Mice with a Transcription Factor Sip1 Deletion.

Since genetic mutations during brain development play a significant role in the genesis of epilepsy, and such genetically determined epilepsies are the most difficult to treat, there is a need to study the mechanisms of epilepsy development with deletions of various transcription factors. We utilized heterozygous mice (Sip1wt/fl) with a neuronal deletion of the transcription factor Sip1 (Smad interacting protein 1) in the cerebral cortex. These mice are characterized by cognitive impairment and are prone to epilepsy. It is known that the brain-derived neurotrophic factor (BDNF) has a neuroprotective effect in various neurodegenerative diseases. Therefore, we created and applied an adeno-associated construct carrying the BDNF sequence selectively in neurons. Using in vitro and in vivo research models, we were able to identify a key gen, the disruption of whose expression accompanies the deletion of Sip1 and contributes to hyperexcitation of neurons in the cerebral cortex. Overexpression of BDNF in cortical neurons eliminated epileptiform activity in neurons obtained from heterozygous Sip1 mice in a magnesium-free model of epileptiform activity (in vitro). Using PCR analysis, it was possible to identify correlations in the expression profile of genes encoding key proteins responsible for neurotransmission and neuronal survival. The effects of BDNF overexpression on the expression profiles of these genes were also revealed. Using BDNF overexpression in cortical neurons of heterozygous Sip1 mice, it was possible to achieve 100% survival in the pilocarpine model of epilepsy. At the level of gene expression in the cerebral cortex, patterns were established that may be involved in the protection of brain cells from epileptic seizures and the restoration of cognitive functions in mice with Sip1 deletion.

Role of Nrf2 in Epilepsy Treatment.

Oxidative stress is a consequence of the disruption of the balance between the generation of reactive nitrogen and oxygen species and the biological system's ability to neutralize those reactive products. Oxidative stress is involved in the generation of many disorders, including epilepsy, which is a prevalent chronic neurological disease that affects the lives of millions of people around the world. Epilepsy is characterized by unforeseeable and repeated seizures that can be very disturbing. Studies have reported that oxidative stress occurs before and after seizures. A transcription factor named Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) controls genes related to the induction of oxidative stress and defends cells against oxidative stress. The Nrf2 protein has seven different domains, ranging from Neh1 to Neh7. Each domain is responsible for a distinctive function of this protein. Keap1 binds to Nrf2, but during oxidative stress, Nrf2 detaches from the Keap1 protein, moves to the nucleus, and binds to DNA. The result of this translocation and binding is the initiation of transcription of detoxifying genes to control the harmful effects of oxidative stress. There is some evidence of oxidative stress involvement in epilepsy. In this review, we have listed potential Nrf2-related therapeutic targets for treating and controlling epilepsy, such as Berberis alkaloids, pentoxifylline, lovastatin, progesterone, and chrysin nanoparticles. These activators were tested in animals (in vivo) and cells (in vitro), and most of these experiments showed promising results in different epilepsy models. Finally, the results have suggested that the activation of Nrf2 can be an option for controlling epilepsy.

Exploring Liraglutide in Lithium-Pilocarpine-Induced Temporal Lobe Epilepsy Model in Rats: Impact on Inflammation, Mitochondrial Function, and Behavior.

Background/Objectives: Glucagon-like peptide-1 receptor agonists such as liraglutide are known for their neuroprotective effects in neurodegenerative disorders, but their role in temporal lobe epilepsy (TLE) remains unclear. We aimed to investigate the effects of liraglutide on several biological processes, including inflammation, antioxidant defense mechanisms, mitochondrial dynamics, and function, as well as cognitive and behavioral changes in the TLE model. Methods: Low-dose, repeated intraperitoneal injections of lithium chloride-pilocarpine hydrochloride were used to induce status epilepticus (SE) in order to develop TLE in rats. Fifty-six male Sprague Dawley rats were subjected and allocated to the groups. The effects of liraglutide on inflammatory markers (NLRP3, Caspase-1, and IL-1β), antioxidant pathways (Nrf-2 and p-Nrf-2), and mitochondrial dynamics proteins (Pink1, Mfn2, and Drp1) were evaluated in hippocampal tissues via a Western blot. Mitochondrial function in peripheral blood mononuclear cells (PBMCs) was examined using flow cytometry. Cognitive-behavioral outcomes were assessed using the open-field, elevated plus maze, and Morris water maze tests. Results: Our results showed that liraglutide modulates NLRP3-mediated inflammation, reduces oxidative stress, and triggers antioxidative pathways through Nrf2 in SE-induced rats. Moreover, liraglutide treatment restored Pink1, Mfn2, and Drp1 levels in SE-induced rats. Liraglutide treatment also altered the mitochondrial function of PBMCs in both healthy and epileptic rats. This suggests that treatment can modulate mitochondrial dynamics and functions in the brain and periphery. Furthermore, in the behavioral aspect, liraglutide reversed the movement-enhancing effect of epilepsy. Conclusions: This research underscores the potential of GLP-1RAs as a possibly promising therapeutic strategy for TLE.

The Interactions of Resveratrol and Sodium Valproate on Penicillin-Induced Epilepsy Model: Electrophysiological and Molecular Study.

Epilepsy represents the most prevalent chronic neurological disease, characterized by spontaneous recurrent seizures. In experimental epilepsy models created by different methods, resveratrol has been demonstrated to reduce epileptiform activity and exhibit neuroprotective properties. A penicillin-induced model of epileptogenesis was used to investigate the effects of resveratrol and its combination with sodium valproate on epileptiform activity. The study design was an in vivo animal experimental study. Forty Wistar-albino rats were divided into five groups, each with eight rats. The groups are categorized as the saline group, penicillin group (only penicillin), resveratrol group, sodium valproate group, and resveratrol + sodium valproate group. ECoG recording was taken for 180min in all groups and statistically evaluated. GABAα1, mGluR1/mGluR5, NMDAR1 receptor expressions in the hippocampus, and S100B level in serum were measured. The spike frequency decreased statistically to 60th min in the sodium valproate group and 150th min in the resveratrol group. The spike frequency decreased statistically in the 20th min and later measurements of the recording in the resveratrol + sodium valproate group. GABAα1 receptor expression was increased in all groups compared to the penicillin group. mGluR1/mGluR5, NMDAR1 receptor expression was decreased in all groups compared to the penicillin group. Serum S100B level increased in all groups compared to the penicillin group. There was no statistically significant difference in epileptiform activity when resveratrol alone was administered in the penicillin-induced epilepsy model. Resveratrol co-administered with sodium valproate significantly reduced epileptiform activity. Co-administration of the sodium valproate + resveratrol group made the receptor level's highest GABAα1receptor expression at receptors.

Neural dynamics and seizure correlations: Insights from neural mass models in a Tetanus Toxin rat model of epilepsy

This study focuses on the use of a neural mass model to investigate potential relationships between functional connectivity and seizure frequency in epilepsy. We fitted a three-layer neural mass model of a cortical column to intracranial EEG (iEEG) data from a Tetanus Toxin rat model of epilepsy, which also included responses to periodic electrical stimulation. Our results show that some of the connectivity weights between different neural populations correlate significantly with the number of seizures each day, offering valuable insights into the dynamics of neural circuits during epileptogenesis. We also simulated single-pulse electrical stimulation of the neuronal populations to observe their responses after the connectivity weights were optimized to fit background (non-seizure) EEG data. The recovery time, defined as the time from stimulation until the membrane potential returns to baseline, was measured as a representation of the critical slowing down phenomenon observed in nonlinear systems operating near a bifurcation boundary. The results revealed that recovery times in the responses of the computational model fitted to the EEG data were longer during 5 min periods preceding seizures compared to 1 hr before seizures in four out of six rats. Analysis of the iEEG recorded in response to electrical stimulation revealed results similar to the computational model in four out of six rats. This study supports the potential use of this computational model as a model-based biomarker for seizure prediction when direct electrical stimulation to the brain is not feasible.

Long‑term effects of vitexin against development of pentylenetetrazole‑induced kindling in rats.

Evidence is provided that the glycosylated flavonoid vitexin (apigenin‑8‑C‑beta‑D‑glucopyranoside) attenuates pentylenetetrazole (PTZ)‑induced acute tonic‑clonic seizures in rats. However, the effects of chronic and systemic vitexin in PTZ‑kindled rats remain unknown. The aim of this work was to investigate the effect of long‑term treatment with vitexin in the PTZ‑kindling model of epilepsy. Male Wistar rats received intraperitoneal injections of PTZ at a subconvulsive dose of 35 mg/kg every other day for 29 days. Either saline containing dimethyl sulfoxide - DMSO 1% (vehicle), diazepam (2 mg/kg; positive control) or vitexin (2.5 mg/kg) was administered intraperitoneally 30 min before each PTZ injection. The behavioral reactions were recorded by 30 min immediately after each PTZ injection. Furthermore, on the 31st day, that is, 48 h after the latter dose of PTZ, the animals were euthanized and renal and hepatic biochemical markers were evaluated in blood serum. Chronic treatment with either diazepam or vitexin attenuated the seizures provoked by PTZ injections. Neither diazepam nor vitexin caused changes in renal levels of creatinine and urea and in hepatic levels of aspartate aminotransferase and alanine aminotransferase. Our findings suggest that chronic administration of vitexin attenuates the progression of PTZ‑induced kindling without causing side effects on kidneys and liver.

Optogenetic stimulation of dorsal striatum bidirectionally controls seizures.

Engagement of the striatum (caudate/putamen) and other basal ganglia nuclei during seizures was first observed over 75 years ago. Basal ganglia output nuclei, and the substantia nigra pars reticulata, in particular, have well-established anti-seizure effects across a large array of experimental models. However, striatal control of seizures is understudied. To address this gap, we used optogenetic approaches to activate and inactivate neurons in the dorsal striatum of Sprague-Dawley rats submitted to the gamma-butyrolactone (GBL) model of absence epilepsy, amygdala kindling model of temporal lobe epilepsy, and pilocarpine-induced Status Epilepticus (SE). All tests were performed on a within-subject basis. Animals were tested in two different light frequencies (5 Hz and 100 Hz). Open-loop (continuous light delivery) optogenetic activation of the dorsal striatal neurons robustly suppressed seizures in all models. On the other hand, optogenetic silencing of the dorsal striatal neurons increased absence seizure expression and facilitated SE onset but had no effect on kindled limbic seizures. In the GBL model, we also verified if the closed- loop strategy (light delivery in response to seizure detection) would be enough to induce antiseizure effects. On-demand light delivery in ChR2-expressing animals reduced SWD duration, while the same approach in ArchT-expressing animals increased SWD duration. These results demonstrated previously unrecognized anti-absence effects associated with striatal continuous and on-demand neuromodulation. Together, these findings document a robust, bidirectional role of the dorsal striatum in the control of seizure generation and propagation in a variety of seizure models, including focal seizure onset and generalized seizures.

Ameliorative effect of diclofenac in rotenone corneal kindling model of drug-resistant epilepsy: Edge of dual COX and KMO inhibition

Epilepsy affects millions of people worldwide, about one-third patients with epilepsy exhibits resistance to available antiseizures medications, known as drug-resistant epilepsy (DRE). Mitochondrial dysfunction has been implicated as a hallmark in drug-resistant epilepsy via activation of microglial kynurenine 3-monooxygenase (KMO) and cyclooxygenase (COX) enzymes, leading to neuroinflammation and oxidative stress. Diclofenac, an equipotent non selective cyclooxygenase inhibitor, has inhibitory action on KMO enzyme and has also shown anti-inflammatory and antioxidant properties in animal models of epilepsy. These properties make it a suitable candidate for amelioration of DRE. However, its potential in drug-resistant epilepsy remained unexplored till date. In this study, dose dependent effect of diclofenac (5 mg/kg, 10 mg/kg, 20 mg/kg) has been explored in rotenone corneal kindling model of mitochondrial DRE. The results of our study revealed the induction of drug resistance to antiseizure medications and induced kynurenine 3-monooxygenase activity in rotenone corneal kindled epileptic mice in comparison to naive mice. Treatment of rotenone corneal kindled epileptic mice with diclofenac resulted in a significant decrease in drug resistance to antiseizure medications as evident by a reduction in seizure score in the treatment groups as compared to control group, in post-treatment resistance validation. The kynurenine 3-monooxygenase inhibitory activity (as evidenced by decreased levels of neurotoxic quinolinic acid) and the antioxidant effect (as evident by significantly reduced oxidative stress) in the diclofenac treated groups, emerged as a major contributor for its ameliorative action. Findings of this study suggests, diclofenac can be used as an adjunct therapy in amelioration of drug-resistant epilepsy.

PPARβ/δ Agonist GW0742 Modulates Microglial and Astroglial Gene Expression in a Rat Model of Temporal Lobe Epilepsy.

The role of astroglial and microglial cells in the pathogenesis of epilepsy is currently under active investigation. It has been proposed that the activity of these cells may be regulated by the agonists of peroxisome proliferator-activated nuclear receptors (PPARs). This study investigated the effects of a seven-day treatment with the PPAR β/δ agonist GW0742 (Fitorine, 5 mg/kg/day) on the behavior and gene expression of the astroglial and microglial proteins involved in the regulation of epileptogenesis in the rat brain within a lithium-pilocarpine model of temporal lobe epilepsy (TLE). TLE resulted in decreased social and increased locomotor activity in the rats, increased expression of astro- and microglial activation marker genes (Gfap, Aif1), pro- and anti-inflammatory cytokine genes (Tnfa, Il1b, Il1rn), and altered expression of other microglial (Nlrp3, Arg1) and astroglial (Lcn2, S100a10) genes in the dorsal hippocampus and cerebral cortex. GW0742 attenuated, but did not completely block, some of these impairments. Specifically, the treatment affected Gfap gene expression in the dorsal hippocampus and Aif1 gene expression in the cortex. The GW0742 injections attenuated the TLE-specific enhancement of Nlrp3 and Il1rn gene expression in the cortex. These results suggest that GW0742 may affect the expression of some genes involved in the regulation of epileptogenesis.

A comparison of the antiepileptogenic efficacy of two rationally chosen multitargeted drug combinations in a rat model of posttraumatic epilepsy

Post-traumatic epilepsy (PTE) is a recurrent and often drug-refractory seizure disorder caused by traumatic brain injury (TBI). No single drug treatment prevents PTE, but preventive drug combinations that may prophylax against PTE have not been studied. Based on a systematic evaluation of rationally chosen drug combinations in the intrahippocampal kainate (IHK) mouse model of acquired epilepsy, we identified two multi-targeted drug cocktails that exert strong antiepileptogenic effects. The first, a combination of levetiracetam (LEV) and topiramate, only partially prevented spontaneous recurrent seizures in the model. We therefore added atorvastatin (ATV) to the therapeutic cocktail (TC) to increase efficacy, forming “TC-001”. The second cocktail – a combination of LEV, ATV, and ceftriaxone, termed “TC-002” – completely prevented epilepsy in the mouse IHK model. In the present proof-of-concept study, we tested whether the two drug cocktails prevent epilepsy in a rat PTE model in which recurrent electrographic seizures develop after severe rostral parasagittal fluid percussion injury (FPI). Following FPI, rats were either treated over 3–4 weeks with vehicle or drug cocktails, starting either 1 or 4–6 h after the injury. Using mouse doses of TC-001 and TC-002, no significant antiepileptogenic effect was obtained in the rat PTE model. However, when using allometric scaling of drug doses to consider the differences in body surface area between mice and rats, PTE was prevented by TC-002. Furthermore, the latter drug cocktail partially prevented the loss of perilesional cortical parvalbumin-positive GABAergic interneurons. Plasma and brain drug analysis showed that these effects of TC-002 occurred at clinically relevant levels of the individual TC-002 drug components. In silico analysis of drug-drug brain protein interactions by the STITCH database indicated that TC-002 impacts a larger functional network of epilepsy-relevant brain proteins than each drug alone, providing a potential network pharmacology explanation for the observed antiepileptogenic and neuroprotective effects observed with this combination.

Preoptic area controls sleep-related seizure onset in a genetic epilepsy mouse model.

In genetic and refractory epileptic patients, seizure activity exhibits sleep-related modulation/regulation and sleep and seizure are intermingled. In this study, by using one het Gabrg2 Q390X KI mice as a genetic epilepsy model and optogenetic method in vivo , we found that subcortical POA neurons were active within epileptic network from the het Gabrg2 Q390X KI mice and the POA activity preceded epileptic (poly)spike-wave discharges(SWD/PSDs) in the het Gabrg2 Q390X KI mice. Meanwhile, as expected, the manipulating of the POA activity relatively altered NREM sleep and wake periods in both wt and the het Gabrg2 Q390X KI mice. Most importantly, the short activation of epileptic cortical neurons alone did not effectively trigger seizure activity in the het Gabrg2 Q390X KI mice. In contrast, compared to the wt mice, combined the POA nucleus activation and short activation of the epileptic cortical neurons effectively triggered or suppressed epileptic activity in the het Gabrg2 Q390X KI mice, indicating that the POA activity can control the brain state to trigger seizure incidence in the het Gabrg2 Q390X KI mice in vivo. In addition, the suppression of POA nucleus activity decreased myoclonic jerks in the Gabrg2 Q390X KI mice. Overall, this study discloses an operational mechanism for sleep-dependent seizure incidence in the genetic epilepsy model with the implications for refractory epilepsy. This operational mechanism also underlies myoclonic jerk generation, further with translational implications in seizure treatment for genetic/refractory epileptic patients and with contribution to memory/cognitive deficits in epileptic patients.

Putative Role of Adenosine A1 Receptors in Exogenous Ketone Supplements-Evoked Anti-Epileptic Effect.

Approximately 30% of patients with epilepsy are drug-refractory. There is an urgent need to elucidate the exact pathophysiology of different types of epilepsies and the mechanisms of action of both antiseizure medication and metabolic therapies to treat patients more effectively and safely. For example, it has been demonstrated that exogenous ketone supplement (EKS)-generated therapeutic ketosis, as a metabolic therapy, may decrease epileptic activity in both animal models and humans, but its exact mechanism of action is unknown. However, it was demonstrated that therapeutic ketosis, among others, can increase adenosine level, which may enhance activity of A1 adenosine receptors (A1Rs) in the brain. It has also been demonstrated previously that adenosine has anti-epileptic effect through A1Rs in different models of epilepsies. Thus, it is possible that (i) therapeutic ketosis generated by the administration of EKSs may exert its anti-epileptic effect through, among other mechanisms, increased adenosine level and A1R activity and that (ii) the enhanced activity of A1Rs may be a necessary anti-epileptic mechanism evoked by EKS administration-generated ketosis. Moreover, EKSs can evoke and maintain ketosis without severe side effects. These results also suggest that the therapeutic application of EKS-generated ketosis may be a promising opportunity to treat different types of epilepsies. In this literature review, we specifically focus on the putative role of A1Rs in the anti-epileptic effect of EKS-induced ketosis.

Dual-responsive two-photon probe for specific lipid droplets near-infrared fluorescence imaging in the brain of epileptic mice

Abnormal lipid metabolism in glial cells is a key pathological feature of epilepsy. The identification of lipid droplets (LDs) is essential for investigating lipid metabolism, disease progression, and potential therapeutic interventions. Two-photon imaging technology enables real-time visualization of the spatial distribution and temporal dynamics of LDs in epilepsy models. In this study, we developed a novel two-photon excited dual-responsive near-infrared fluorescent probe, CabA, based on viscosity and polarity, to monitor dynamic changes in LDs. The fluorescence of CabA at 670 nm exhibits a significant increase in response to low polarity and high viscosity due to the twisted intramolecular charge transfer and intramolecular charge transfer mechanisms. The LDs-targeting capability of CabA at the cellular level and the process of LDs generation between neurons and astrocytes during the pathological advancement of epilepsy have been validated. In situ synchronous imaging experiments in epileptic and normal mice using CabA revealed abnormal LDs accumulation in the brain during seizures. Two-photon fluorescence imaging further demonstrated LDs accumulation in the brains of epileptic mice at a penetration depth of 100 μm. This study offers a valuable tool for enhancing the understanding of LDs in physiological and pathological processes, potentially aiding in the early diagnosis of epilepsy.

Subthreshold Cannabidiol Potentiates Levetiracetam in the Kainic Acid Model of Temporal Lobe Epilepsy: A Pilot Study.

Refractoriness to antiseizure medications is still a major concern in the pharmacotherapy of epilepsy. For this reason, we decided to evaluate the combination of levetiracetam and cannabidiol, administered at a subthreshold dose, to limit the possible adverse effects of this phytocannabinoid. We administered levetiracetam (300 mg/kg/day, via osmotic minipumps), cannabidiol (120 mg/kg/day, injected once a day subcutaneously), or their combination for one week in epileptic rats. Saline-treated epileptic rats were the control group. Animals were monitored with video electroencephalography the week before and after the treatment. No changes were found in the controls. Levetiracetam did not significantly reduce the total seizure number or the overall seizure duration. Still, the overall number of seizures (p < 0.001, Duncan's new multiple range test) and their total duration (p < 0.01) increased in the week following treatment withdrawal. Cannabidiol did not change seizures when administered as a single drug. Instead, levetiracetam combined with cannabidiol resulted in a significant reduction in the overall number and duration of seizures (p < 0.05), when comparing values measured during treatment with both pre- and post-treatment values. These findings depended on changes in convulsive seizures, while non-convulsive seizures were stable. These results suggest that cannabidiol determined a remarkable potentiation of levetiracetam antiseizure effects at a subthreshold dose.

Early life stress influences epilepsy outcomes in mice.

Stress is a common seizure trigger that has been implicated in worsening epilepsy outcomes. The neuroendocrine response to stress is mediated by the hypothalamic-pituitary-adrenal (HPA) axis and HPA axis dysfunction worsens epilepsy outcomes, increasing seizure burden, behavioral comorbidities, and risk for sudden unexpected death in epilepsy (SUDEP) in mice. Early life stress (ELS) reprograms the HPA axis into adulthood, impacting both the basal and stress-induced activity. Thus, we propose that ELS may influence epilepsy outcomes by influencing the function of the HPA axis. To test this hypothesis, we utilized the maternal separation paradigm and examined the impact on seizure susceptibility. We show that ELS exerts a sex dependent effect on seizure susceptibility in response to acute administration of the chemoconvulsant, kainic acid, which is associated with an altered relationship between seizure activity and HPA axis function. To further examine the impact of ELS on epilepsy outcomes, we utilized the intrahippocampal kainic acid model of chronic epilepsy in mice previously exposed to maternal separation. We find that the relationship between corticosterone levels and the extent of epileptiform activity is altered in mice subjected to ELS. We demonstrate that ELS impacts behavioral outcomes associated with chronic epilepsy in a sex-dependent manner, with females being more affected. We also observe reduced mortality (presumed SUDEP) in female mice subjected to ELS, consistent with previous findings suggesting a role for HPA axis dysfunction in SUDEP risk. These data demonstrate for the first time that ELS influences epilepsy outcomes and suggest that previous life experiences may impact the trajectory of epilepsy.

Modeling Cortical Versus Hippocampal Network Dysfunction in a Human Brain Assembloid Model of Epilepsy and Intellectual Disability.

Neurodevelopmental disorders often impair multiple cognitive domains. For instance, a genetic epilepsy syndrome might cause seizures due to cortical hyperexcitability and present with memory impairments arising from hippocampal dysfunction. This study examines how a single disorder differentially affects distinct brain regions by using human patient iPSC-derived cortical- and hippocampal-ganglionic eminence assembloids to model Developmental and Epileptic Encephalopathy 13 (DEE-13), a condition arising from gain-of-function mutations in the SCN8A gene. While cortical assembloids showed network hyperexcitability akin to epileptogenic tissue, hippocampal assembloids did not, and instead displayed network dysregulation patterns similar to in vivo hippocampal recordings from epilepsy patients. Predictive computational modeling, immunohistochemistry, and single-nucleus RNA sequencing revealed changes in excitatory and inhibitory neuron organization that were specific to hippocampal assembloids. These findings highlight the unique impacts of a single pathogenic variant across brain regions and establish hippocampal assembloids as a platform for studying neurodevelopmental disorders.

Candesartan restores blood-brain barrier dysfunction, mitigates aberrant gene expression, and extends lifespan in a knockin mouse model of epileptogenesis.

Blockade of Angiotensin type 1 receptor (AT1R) has potential therapeutic utility in the treatment of numerous detrimental consequences of epileptogenesis, including oxidative stress, neuroinflammation, and blood-brain barrier (BBB) dysfunction. We have recently shown that many of these pathological processes play a critical role in seizure onset and propagation in the Scn8a-N1768D mouse model. Here we investigate the efficacy and potential mechanism(s) of action of candesartan (CND), an FDA-approved angiotensin receptor blocker (ARB) indicated for hypertension, in improving outcomes in this model of pediatric epilepsy. We compared length of lifespan, seizure frequency, and BBB permeability in juvenile (D/D) and adult (D/+) mice treated with CND at times after seizure onset. We performed RNAseq on hippocampal tissue to quantify differences in genome-wide patterns of transcript abundance and inferred beneficial and detrimental effects of canonical pathways identified by enrichment methods in untreated and treated mice. Our results demonstrate that treatment with CND gives rise to increased survival, longer periods of seizure freedom, and diminished BBB permeability. CND treatment also partially reversed or 'normalized' disease-induced genome-wide gene expression profiles associated with inhibition of NF-κB, TNFα, IL-6, and TGF-β signaling in juvenile and adult mice. Pathway analyses reveal that efficacy of CND is due to its known dual mechanism of action as both an AT1R antagonist and a PPARγ agonist. The robust effectiveness of CND across ages, sexes and mouse strains is a positive indication for its translation to humans and its suitability of use for clinical trials in children with SCN8A epilepsy.

Enhanced Fyn-tau and NR2B-PSD95 interactions in epileptic foci in experimental models and human epilepsy.

Epilepsy and Alzheimer's disease share some common pathologies such as neurodegeneration, seizures and impaired cognition. However, the molecular mechanisms of these changes are still largely unknown. Fyn, a Src-family non-receptor tyrosine kinase (SFK), and its interaction with tau in mediating brain pathology in epilepsy and Alzheimer's disease can be a potential therapeutic target for disease modification. Although Fyn and tau pathology occurs in both Alzheimer's disease and epilepsy, the dynamics of Fyn-tau and PSD95-NR2B interactions affected by seizures and their impact on brain pathology in epilepsy have not been investigated. In this study, we demonstrate a significant increase of Fyn-tau interactions following seizure induction by kainate in both acute and chronic rodent models and in human epilepsy. In the early phase of epileptogenesis, we show increased Fyn/tau/NR2B/PSD95/neuronal nitric oxide synthase complexes after status epilepticus and a postsynaptic increase of phosphorylated tau (pY18 and AT8), Fyn (pSFK-Y416), NMDAR (pNR2B-Y1472) and neuronal nitric oxide synthase. Hippocampal proximity ligation assay and co-immunoprecipitation revealed a sustained increase of Fyn-tau and NR2B-PSD95 complexes/binding in rat chronic epilepsy at 3 months post-status epilepticus. Enhanced Fyn-tau complexes strongly correlated with the frequency of spontaneously recurring convulsive seizures and epileptiform spikes in the chronic epilepsy model. In human epileptic brains, we also identified increased Fyn-tau and NR2B-PSD95 complexes, tau phosphorylation (pY18 and AT8) and Fyn activation (pSFK-Y416), implying the translational and therapeutic potential of these molecular interactions. In tau knockout mice and in rats treated with a Fyn/SFK inhibitor saracatinib, we found a significant reduction of phosphorylated Fyn, tau (AT8 in saracatinib-treated), NR2B and neuronal nitric oxide synthase and their interactions (Fyn-tau and NR2B-PSD95 in saracatinib-treated group; NR2B-PSD95 in tau knockout group). The reduction of Fyn-tau and NR2B-PSD95 interactions in the saracatinib-treated group, in contrast to the vehicle-treated group, correlated with the modification in seizure progression in the rat chronic epilepsy model. These findings from animal models and human epilepsy provide evidence for the role of Fyn-tau and NR2B-PSD95 interactions in seizure-induced brain pathology and suggest that blocking such interactions could modify the progression of epilepsy.