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Objective: Sudden unexpected death in epilepsy (SUDEP) results in more years of potential life lost than any neurological condition with the exception of stroke. It is generally agreed that SUDEP happens due to some form of respiratory, cardiac, and electrocerebral dysfunction following a seizure; however, the mechanistic cause of these perturbations is unclear. One possible explanation lies with adenosinergic signaling. Extracellular levels of the inhibitory neuromodulator adenosine rapidly rise during seizures, a countermeasure that is necessary for seizure termination. Previous evidence has suggested that excessive adenosinergic inhibition could increase the risk of SUDEP by silencing brain areas necessary for life, such as the respiratory nuclei of the brainstem. The goal of this investigation was to further clarify the role of adenosine in seizure‐induced respiratory and electrocerebral dysfunction. Methods: To determine the role of adenosine in postictal physiological dysregulation, we pharmacologically manipulated adenosine signaling prior to amygdala‐kindled seizures in mice while recording electroencephalogram (EEG), electromyogram, and breathing using whole body plethysmography. The adenosinergic drugs used in this study included selective and nonselective adenosine receptor antagonists and inhibitors of adenosine metabolism. Results: We found that high doses of adenosine receptor antagonists caused some seizures to result in seizure‐induced death; however, counterintuitively, animals in these conditions that did not experience seizure‐induced death had little or no postictal generalized EEG suppression. Inhibitors of adenosine metabolism had no effect on postictal breathing but did worsen some postictal electrocerebral outcomes. Significance: The unexpected effect of high doses of adenosine antagonists on seizure‐induced death observed in this study may be due to the increase in seizure severity, vasoconstriction, or phosphodiesterase inhibition caused by these drugs at high doses. These findings further clarify the role of adenosine in seizure‐induced death and may have implications for the consumption of caffeine in epilepsy patients and the prevention of SUDEP. [ABSTRACT FROM AUTHOR]

Abstract Objective Alcohol‐related seizures (ARS) are one of the most important consequences of alcohol withdrawal syndrome (AWS). However, demographic and clinical characteristics, and furthermore, the relationship of ARS with delirium tremens (DT), have not yet been evaluated in detail. Therefore, the aim of the present study was to reveal the correlates of ARS and examine the interaction of ARS with the occurrence of DT and with the severity of AWS. Methods In the retrospective study (Study 1) 2851 medical charts of inpatient admissions characterized by AWS and DT were listed. Demographic and clinical variables of ARS were assessed. In the follow‐up study (Study 2), patients admitted with AWS without (N = 28) and with (N = 18) ARS were enrolled. Study 1 was performed between 2008 and 2023, and Study 2 was performed in 2019 in Hungary. To determine the severity of AWS, the Clinical Institute Withdrawal Assessment Scale for Alcohol, Revised (CIWA‐Ar) was used. ARS is a provoked, occasional seizure; therefore, patients with epilepsy syndrome were excluded from the two studies. Statistical analyses were performed by the means of chi‐square tests, multinomial logistic regressions, mixed ANOVA, and derivation. Results The occurrence of DT, the history of ARS, and somatic co‐morbidities were found to be risk factors for the appearance of ARS. ARS was proved to be a risk factor for the development of DT. In the follow‐up study, there was no difference in the decrease of CIWA‐Ar scores between the groups. Significance Our present findings support the likelihood of kindling, which is one of the most important mechanisms underlying the development of ARS, but do not directly prove its presence. Additionally, our results revealed that the severity of AWS is not influenced by the presence of ARS. Plain Language Summary Provoked, occasional seizures during AWS are defined as ARS. In the present study, predictors and interactions of these seizures with DT—the most severe form of withdrawal—and with the severity of withdrawal were examined in retrospective and follow‐up studies. The present study shows that a history of withdrawal seizures, the occurrence of DT, and somatic comorbidities are predictors of the development of seizures. Furthermore, our findings suggest that the presence of seizures does not influence the severity of withdrawal.

Introduction: Epileptic seizures are thought to be caused by the impaired balance between excitatory (glutamate) and inhibitor [gamma amino butyric acid (GABA)] neurotransmitters in the brain. Neuropeptides have potent modulator properties on these neurotransmitters.Objective: Ghrelin exerts anticonvulsant effects in an acute pentylenetetrazole (PTZ) model. However, the effect of repeated ghrelin injections in chronic pentylenetetrazole kindling model is not known. In this study, the effects of repeated ghrelin administration on seizure scores, working memory, locomotor activity, oxidative biomarkers, and neurochemical parameters in PTZ kindling in rats was examined.Methods: For this purpose, 35 mg/kg of PTZ was administered intraperitoneally to the experimental groups. The rats also received physiological saline/diazepam or ghrelin before each PTZ injection. After behavioural analysis (Y-maze, rotarod, and locomotor activity tests), biochemical and neurochemical analyses were conducted using ELISA.Results: PTZ administration induced progression in the seizure scores and all of the rats in the PS + PTZ group were kindled with the 20th injection. Ghrelin treatment significantly reduced the seizure scores. The difference among the groups in terms of the Y-maze, locomotor activity, and rotarod tests was nonsignificant. PTZ administration significantly decreased the brain GABA, CAT, and AChE levels, and increased the MDA, NO, and protein carbonyl levels. Repeated ghrelin treatment ameliorated the GABA, AChE, CAT, MDA, NO, and protein carbonyl levels.Conclusion: Taken together, the results indicated that repeated ghrelin treatment had antioxidant, and anticonvulsant activity on PTZ kindling in rats. [ABSTRACT FROM AUTHOR]

Objective: Alcohol‐related seizures (ARS) are one of the most important consequences of alcohol withdrawal syndrome (AWS). However, demographic and clinical characteristics, and furthermore, the relationship of ARS with delirium tremens (DT), have not yet been evaluated in detail. Therefore, the aim of the present study was to reveal the correlates of ARS and examine the interaction of ARS with the occurrence of DT and with the severity of AWS. Methods: In the retrospective study (Study 1) 2851 medical charts of inpatient admissions characterized by AWS and DT were listed. Demographic and clinical variables of ARS were assessed. In the follow‐up study (Study 2), patients admitted with AWS without (N = 28) and with (N = 18) ARS were enrolled. Study 1 was performed between 2008 and 2023, and Study 2 was performed in 2019 in Hungary. To determine the severity of AWS, the Clinical Institute Withdrawal Assessment Scale for Alcohol, Revised (CIWA‐Ar) was used. ARS is a provoked, occasional seizure; therefore, patients with epilepsy syndrome were excluded from the two studies. Statistical analyses were performed by the means of chi‐square tests, multinomial logistic regressions, mixed ANOVA, and derivation. Results: The occurrence of DT, the history of ARS, and somatic co‐morbidities were found to be risk factors for the appearance of ARS. ARS was proved to be a risk factor for the development of DT. In the follow‐up study, there was no difference in the decrease of CIWA‐Ar scores between the groups. Significance: Our present findings support the likelihood of kindling, which is one of the most important mechanisms underlying the development of ARS, but do not directly prove its presence. Additionally, our results revealed that the severity of AWS is not influenced by the presence of ARS. Plain Language Summary: Provoked, occasional seizures during AWS are defined as ARS. In the present study, predictors and interactions of these seizures with DT—the most severe form of withdrawal—and with the severity of withdrawal were examined in retrospective and follow‐up studies. The present study shows that a history of withdrawal seizures, the occurrence of DT, and somatic comorbidities are predictors of the development of seizures. Furthermore, our findings suggest that the presence of seizures does not influence the severity of withdrawal. [ABSTRACT FROM AUTHOR]

Seizures beget seizures is a longstanding theory that proposed that seizure activity can impact the structural and functional properties of the brain circuits in ways that contribute to epilepsy progression and the future occurrence of seizures. Originally proposed by Gowers, this theory continues to be quoted in the pathophysiology of epilepsy. We critically review the existing data and observations on the consequences of recurrent seizures on brain networks and highlight a range of factors that speak for and against the theory. The existing literature demonstrates clearly that ictal activity, especially if recurrent, induces molecular, structural, and functional changes including cell loss, connectivity reorganization, changes in neuronal behavior, and metabolic alterations. These changes have the potential to modify the seizure threshold, contribute to disease progression, and recruit wider areas of the epileptic network into epileptic activity. Repeated seizure activity may, thus, act as a pathological positive‐feedback mechanism that increases seizure likelihood. On the other hand, the time course of self‐limited epilepsies and the presence of seizure remission in two thirds of epilepsy cases and various chronic epilepsy models oppose the theory. Experimental work showed that seizures could induce neural changes that increase the seizure threshold and decrease the risk of a subsequent seizure. Due to the complex nature of epilepsies, it is wrong to consider only seizures as the key factor responsible for disease progression. Epilepsy worsening can be attributed to the various forms of interictal epileptiform activity or underlying disease mechanisms. Although seizure activity can negatively impact brain structure and function, the "seizures beget seizures" theory should not be used dogmatically but with extreme caution. [ABSTRACT FROM AUTHOR]

Lilii Bulbus (Lilium lancifolium Thunberg) has a proneurogenic effect on the hippocampus. However, its effects on epilepsy and associated pathological features remain unknown. In this study, we investigated the antiseizure effects of a water extract of Lilii Bulbus (WELB) in mouse model of pentylenetetrazol (PTZ)-induced seizure. Mice were injected with PTZ once every 48 h until full kindling was achieved. WELB (100 and 500 mg/kg) was orally administered once daily before PTZ administration and during the kindling process. We found that WELB treatment protected against PTZ-induced low seizure thresholds and high seizure severity. Further, WELB-treated mice showed attenuated PTZ kindling-induced anxiety and memory impairment. Immunostaining and immunoblots showed that hyperactivation and ectopic migration of dentate granule cells (DGCs) were significantly reduced by WELB treatment in PTZ kindling-induced seizure mice. Staining for mossy fiber sprouting (MFS) using Timm staining and ZnT3 showed that WELB treatment significantly decreased PTZ kindling-induced MFS. Furthermore, the increased or decreased expression of proteins related to ectopic DGCs (Reelin and Dab-1), MFS (Netrin-1, Sema3A, and Sema3F), and their downstream effectors (ERK, AKT, and CREB) in the hippocampus of PTZ kindling mice was significantly restored by WELB treatment. Overall, our findings suggest that WELB is a potential antiseizure drug that acts by reducing ectopic DGCs and MFS and modulating epileptogenesis-related signaling in the hippocampus.

Chemical kindling is broadly used experimental model to investigate novel treatments on the process of epileptogenesis and coexisting behavioral comorbidities. The current study aimed to investigate the low dose perampanel (PER) (0.125 and 0.5 mg/kg) and pregabalin (PG) (15 mg/kg) as standalone treatments and in combination on kindling-induced seizure progression with concurrent electroencephalographic alterations. Mice were subjected to pentylenetetrazole (PTZ)-induced kindling followed by neurobehavioral assessment for anxiety-like activity and cognitive deficit through behavioral experiments. The monotherapy with PER at 0.5 mg/kg and PG at 15 mg/kg delayed the kindling process but PRP+PG yielded pronounced benefits and hindered the development of seizures of higher severity. PER+PG combination relieved the animals from anxiety-like behavior in various employed anxiogenic tests. Furthermore, the kindling-associated cognitive deficit was protected by PER+PG combination as increased alteration behavior, discrimination index and latencies to enter the dark zone were noted in y-maze, object recognition and passive avoidance tests, respectively while shorter escape latencies were noted in water maze. The brain samples of kindled mice had elevated malondialdehyde and reduced catalase, superoxide dismutase and glutathione peroxidase enzymes while treatment with PER and PG combination shielded the mice from heightened kindling-associated oxidative stress. Overall, the findings of the present study illustrate that concurrent administration of PER and PG effectively hindered the process of epileptogenesis by protecting neuronal excitability and brain oxidative stress. The results predict the dominance of PER and PG combination over monotherapy which might serve as an effective novel combination to combat drug resistance and behavioral disorders in epileptic patients.

The kindling model has been used extensively by researchers to study the neurobiology of temporal lobe epilepsy (TLE) due to its capacity to induce intensification of seizures by the progressive recruitment of additional neuronal clusters into epileptogenic networks. We applied repetitive focal optogenetic activation of putative excitatory neurons in the dorsal CA1 area of the hippocampus of mice to investigate the role of inhibitory signaling during this process. This experimental protocol resulted in a kindling phenotype that was maintained for 2weeks after the animals were fully kindled. As a result of the different phases of optogenetic kindling (OpK), key inhibitory signaling elements, such as KCC2 and NKCC1, exhibited distinct temporal and spatial dynamics of regulation. These alterations in protein expression were related to the distinct pattern of ictal activity propagation through the different hippocampal sublayers. Our results suggest the KCC2 disruption in the contralateral hippocampus of fully kindled animals progressively facilitated the creation of pathological pathways for seizure propagation through the hippocampal network. Upon completion of kindling, we observed animals that were restimulated after a rest period of 14-day showed, besides a persistent KCC2 downregulation, an NKCC1 upregulation in the bilateral dentate gyrus and hippocampus-wide loss of parvalbumin-positive interneurons. These alterations observed in the chronic phase of OpK suggest that the hippocampus of rekindled animals continued to undergo self-modifications during the rest period. The changes resulting from this period suggest the possibility of the development of a mirror focus on the hippocampus contralateral to the site of optical stimulations. Our results offer perspectives for preventing the recruitment and conversion of healthy neuronal networks into epileptogenic ones among patients with epilepsy. [ABSTRACT FROM AUTHOR]

Macrophage/microglia are activated after Traumatic brain injury (TBI), transform to inflammatory phenotype (M1) and trigger neuroinflammation, which provokes epileptogenesis. Interleukin-4 (IL-4) is a well-known drive of macrophage/microglia to the anti-inflammatory phenotype (M2). We tested effect of IL-4 on speed of epileptogenesis, brain expression of inflammatory and anti-inflammatory cytokines, and lesion size in TBI-injured male rats. Rats underwent TBI by Controlled Cortical Impact. Then 100 ng IL-4 was injected into cerebral ventricles. One day after TBI, pentylenetetrazole (PTZ) kindling started and development of generalized seizures was recorded. The lesion size, cell survival rate, TNF-α, TGF-β, IL-10, and Arginase1 (Arg1) was measured in the brain 6 h, 12 h, 24 h, 48 h, and 5 days after TBI. Astrocytes and macrophage/microglia activation/polarization was assessed by GFAP/Arg1 and Iba1/Arg1 immunostaining. TBI-injured rats were kindled by 50% less PTZ injections than control and sham-operated rats. IL-4 did not change kindling rate in sham-operated rats but inhibited acceleration of kindling rate in the TBI-injured rats. IL-4 decreased damage volume and number of destroyed neurons. IL-4 stopped TNF-α whereas upregulated TGF-β, IL-10, and Arg1 expressions. Iba1/Arg1 positive macrophage/microglia was notably increased 48 h after IL-4 administration. IL-4 suppresses TBI-induced acceleration of epileptogenesis in rats by directing TBI neuroinflammation toward an anti-inflammatory tone and inhibition of cell death. [ABSTRACT FROM AUTHOR]

Introduction: Drug-resistant epilepsy is an unmet medical condition that impacts 30% of epileptic patients. Numerous antiseizure drugs have already been developed but they provide only symptomatic relief and do not target the underlying pathogenesis. Preclinical models provide opportunities to gain insights into obscure mechanisms of drug-resistant epilepsy. Current animal models possess lacunae that need rectification and validation to discover novel antiepileptic drugs. The present study aims to validate 3 different doses of phenobarbital at 2 different periods. Methods: Pentylenetetrazole was given at a sub-convulsive dose (30 mg/kg/day/intraperitoneal [IP]) for 28 days to develop kindling in male Wistar rats. Further, kindled rats were divided into the following four groups: Pentylenetetrazole control, pentylenetetrazole and phenobarbital (20 mg/kg), pentylenetetrazole and phenobarbital 40 mg/kg, and pentylenetetrazole and phenobarbital (60 mg/kg). They were assessed on days 14 and 28 post-kindling. Seizure scoring, oxidative stress, phenobarbital plasma levels, and histopathology of hippocampal neurons were analyzed. Results: The results showed that the combination of pentylenetetrazole and phenobarbital (40 and 60 mg/kg) remarkably decreased seizure score, elucidated higher antioxidant effect, and prevented neuronal injury on day 14, whereas increased seizure score, oxidative stress, and neuronal death was observed with chronic administration of pentylenetetrazole and phenobarbital in kindled rats at day 28. Moreover, phenobarbital levels in blood were significantly increased at day 28 of phenobarbital treatment compared to day 14. Conclusion: The adapted protocol with phenobarbital 40 mg/kg dose could be of great potential in screening antiseizure drugs in refractory epilepsy. [ABSTRACT FROM AUTHOR]

Objectives: In this study, tetramethylpyrazine (TMP) was evaluated for its therapeutic potential as an alternative therapy for epileptogenesis and its associated comorbidities in rats. Methods: The sub-convulsant dose of pentylenetetrazole (PTZ) (35 mg/kg, intraperitoneally) was injected on alternative days to produce kindling for 32 days and observed for seizure score percent of kindled animals in each group. After kindling, the animals were evaluated in models of anxiety, memory and predictive of depression. The neuroprotective effect of TMP was assessed by estimating the biochemical parameters in the cortex and hippocampus of the brain. Histopathological alterations were also observed in the cortex and hippocampus (CA1, CA3 and DG). Key findings: The administration of TMP reduced the seizure score and percentage of kindled animals dose-dependently. Furthermore, TMP significantly improved the behavioural parameters measured in the predictive models of depression but not in the anxiety and cognitive performances of the animals. The oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations in the brain induced by PTZ were significantly mitigated by administering the TMP high dose of 60 mg/kg. Conclusion: In conclusion, the TMP attenuated the depression behaviour in the PTZ-induced kindled rats, and reduced the oxidative-nitrosative stress, excitotoxicity, neuroinflammation and histological alterations of the brain. Graphical Abstract [ABSTRACT FROM AUTHOR]

Lateral fluid percussion injury (LFPI) in rats is used to model post-traumatic epilepsy (PTE), with spontaneous seizures occurring in up to ½ of the subjects. Using the kindling paradigm, we examined whether animals without detectable seizures had an altered seizure susceptibility. Male Sprague Dawley rats were subjected to LFPI. Seven-nine months later, spontaneous seizures were monitored for two weeks. Afterward, the animals underwent kindling of basolateral amygdala. For kindling outcomes, the animals were categorized based on the 95% confidence intervals of mean number trials to kindling (ie 3 consecutive stage 4-5 seizures). Spontaneous seizures were detected in 7 out of 24 rats. There was no correlation between the severity of LFPI and either baseline afterdischarge properties, or kindling rates. Six LFPI rats kindled at a rate comparable to those in sham-LFPI (n = 10) and in naïve (n = 7) subjects. Ten LFPI rats kindled faster and 8-slower than controls. None of slow-kindling rats had spontaneous seizures during the prekindling monitoring. During the same period, six fast-kindling and three normal-kindling rats had been seizure-free. Thus, kindling reveals a diversity to seizure susceptibility after LFPI beyond an overt seizure symptomatology, ranging from the increased susceptibility to the increased resistance.

Tesfaye Desalegn, Ephrem Engidawork Department of Pharmacology and Clinical Pharmacy, School of Pharmacy, College of Health Sciences, Addis Ababa University, Addis Ababa, EthiopiaCorrespondence: Ephrem Engidawork, Department of Pharmacology and Clinical Pharmacy, School of Pharmacy, College of Health Sciences, Addis Ababa University, P. O. Box 9086, Addis Ababa, Ethiopia, Email ephrem.engidawork@aau.edu.etBackground: The leaves of Ajuga integrifolia Buch.-Ham. ex D.Don (Lamiaceae) have long been used as an anti-convulsant remedy in Ethiopian traditional medicine. However, the evidence supporting their use is sparse in the literature. This study was conducted to add to the existing body of knowledge about the anti-convulsant activity of the plant.Methods: The anti-convulsant activity of the extract was investigated in both acute (pentylenetetrazol [PTZ], 80 mg/kg; and maximal electroshock [MES]) and chronic (PTZ, 35 mg/kg) kindling seizure models. For the experimental paradigms, various doses of the extract (100, 200, and 400 mg/kg) were administered. Positive controls received sodium valproate (200 mg/kg) for the PTZ model and phenytoin (25 mg/kg) for the MES model. Parameters including the onset of clonus and duration of hindlimb tonic extension were recorded and compared with controls. Moreover, the total alkaloid, flavonoid, and phenol contents of the extracts were determined.Results: Ethyl acetate extract produced a superior effect among all solvent extracts in both the PTZ and MES models. At all doses, it significantly delayed the mean onset of clonus (p< 0.01) in the PTZ test compared to controls. It also significantly reduced (p< 0.001) the mean duration of hindlimb tonic extension in the MES model. Treatment of mice with 200 mg/kg (p< 0.01) and 400 mg/kg (p< 0.001) of ethyl acetate extract significantly protected against PTZ-induced kindling compared to controls. The leaf was found to contain 10.002± 0.119 mg atropine equivalent per gram of dry extract of alkaloids, 9.045± 0.8445 mg quercetin equivalent per gram of dry extract of flavonoids, and 21.928± 1.118 mg gallic acid equivalent per gram of dry extract of phenols.Conclusion: This study indicated that the plant A. integrifolia has anti-convulsant activity in both acute and chronic models of seizure. This plant represents a potential source for the development of a new anti-epileptic drug for pharmacoresistant epilepsy.Keywords: Ajuga integrifolia, anti-convulsant, epilepsy, kindling, phytoconstituents, seizure

The kindling model has been used extensively by researchers to study the neurobiology of temporal lobe epilepsy (TLE) due to its capacity to induce intensification of seizures by the progressive recruitment of additional neuronal clusters into epileptogenic networks. We applied repetitive focal optogenetic activation of putative excitatory neurons in the dorsal CA1 area of the hippocampus of mice to investigate the role of inhibitory signaling during this process. This experimental protocol resulted in a kindling phenotype that was maintained for 2 weeks after the animals were fully kindled. As a result of the different phases of optogenetic kindling (OpK), key inhibitory signaling elements, such as KCC2 and NKCC1, exhibited distinct temporal and spatial dynamics of regulation. These alterations in protein expression were related to the distinct pattern of ictal activity propagation through the different hippocampal sublayers. Our results suggest the KCC2 disruption in the contralateral hippocampus of fully kindled animals progressively facilitated the creation of pathological pathways for seizure propagation through the hippocampal network. Upon completion of kindling, we observed animals that were restimulated after a rest period of 14-day showed, besides a persistent KCC2 downregulation, an NKCC1 upregulation in the bilateral dentate gyrus and hippocampus-wide loss of parvalbumin-positive interneurons. These alterations observed in the chronic phase of OpK suggest that the hippocampus of rekindled animals continued to undergo self-modifications during the rest period. The changes resulting from this period suggest the possibility of the development of a mirror focus on the hippocampus contralateral to the site of optical stimulations. Our results offer perspectives for preventing the recruitment and conversion of healthy neuronal networks into epileptogenic ones among patients with epilepsy.

Recent evidence suggests that P-glycoprotein (P-gp) overexpression mediates hyperexcitability and is associated with epileptogenesis. Transcranial focal electrical stimulation (TFS) delays epileptogenesis and inhibits P-gp overexpression after a generalized seizure. Here, first we measured P-gp expression during epileptogenesis and second, we assessed if TFS antiepileptogenic effect was related with P-gp overexpression avoidance. Male Wistar rats were implanted in right basolateral amygdala and stimulated daily for electrical amygdala kindling (EAK), P-gp expression was assessed during epileptogenesis in relevant brain areas. Stage I group showed 85% increase in P-gp in ipsilateral hippocampus (p < 0.001). Stage III group presented 58% and 57% increase in P-gp in both hippocampi (p < 0.05). Kindled group had 92% and 90% increase in P-gp in both hippocampi (p < 0.01), and 93% and 143% increase in both neocortices (p < 0.01). For the second experiment, TFS was administrated daily after each EAK stimulation for 20 days and P-gp concentration was assessed. No changes were found in the TFS group (p > 0.05). Kindled group showed 132% and 138% increase in P-gp in both hippocampi (p < 0.001) and 51% and 92% increase in both cortices (p < 0.001). Kindled + TFS group presented no changes (p > 0.05). Our experiments revealed that progression of EAK is associated with increased P-gp expression. These changes are structure-specific and dependent on seizure severity. EAK-induced P-gp overexpression would be associated with neuronal hyperexcitability and thus, epileptogenesis. P-gp could be a novel therapeutical target to avoid epileptogenesis. In accordance with this, TFS inhibited P-gp overexpression and interfered with EAK. An important limitation of the present study is that P-gp neuronal expression was not evaluated under the different experimental conditions. Future studies should be carried out to determine P-gp neuronal overexpression in hyperexcitable networks during epileptogenesis. The TFS-induced lessening of P-gp overexpression could be a novel therapeutical strategy to avoid epileptogenesis in high-risk patients. [ABSTRACT FROM AUTHOR]

This study aimed to carry out a comparative study of the main models of chronic epilepsy induced by pentylenetetrazole (PTZ)-kindling method and to assess the efficacy of sodium valproate, one of the main antiepileptics, on the best epilepsy-inducing kindling model. Two sets of 24 animals were divided into 4 groups of 6 animals and treated as follow: Set 1 included: group 1, control; group 2, the classic kindling PTZ group (UKEOD); group 3, PTZ kindling every other day group with challenge (CKEOD); group 4, PTZ kindling every day group, with challenge (CKED); Set 2 included: group 1, control; group 2, CKEOD group; group 3 and 4, receiving either valproate 200 mg/kg or valproate 300 mg/kg + CKEOD procedure. Results show that CKEOD group significantly reduced the number of injections necessary to reach the fully-kindled state, increased the severity of seizures and improved the stability of seizures. In addition, the CKEOD group significantly increased the level of malondialdehyde and GABA transaminase, reduced the level of reduced glutathione, catalase and GABA. Furthermore, it had no impact on plasma levels of alanine aminotransferase (ALAT) and aspartate aminotransferase (ASAT). Valproate 300 mg/kg significantly protected animals against kindling induced by CKEOD. The kindling model with a challenge dose administered on day 1 (CKEOD) thus allows to induce more severe, more stable chronic epilepsy and in a shorter period of time, and could thus contribute to a better understanding of epilepsy, as well as its uses in drug discovery.

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

Introduction Epilepsy is a common neurological disorder that affects millions of people worldwide. While there are many treatment options available, including drug and non-drug therapies, there is still a need for effective treatments that can help manage seizures.The present study aimed to investigate the intensity-dependent effects of mild electric foot stimulation on seizure intensity following pentylenetetrazol (PTZ)chemical kindling in rats. Methods: Kindled seizures were induced in rats by repeated injections of PTZ. Twenty-seven male rats were randomly divided into three groups: kindling group, kindling group + 0.1 mA electrical stimulation, and kindling group + 0.01 mA electrical stimulation. Electrical stimulation was induced using an electric box equipped with steel rods following acquisition of kindled seizures. The intensity of the mild electric foot stimulation was either 0.1 or 0.01 mA depending on the tested group. Results: The study found that while mild electric foot stimulation with intensity of 0. 1 mA had proconvulsive effects on PTZ-induced kindled rats, and decreased the latency to the onset of stage 5 seizure (p<0.05), stimulation with intensity of 0.01 mA did not have significant effects on seizure parameters. Conclusion: Obtained results suggested that mild electric foot stimulation may have anticonvulsant effects, but only at certain intensity. This finding has important implications for future research into the use of mild electric foot stimulation as a treatment for epilepsy. [ABSTRACT FROM AUTHOR]

Background: Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is an emerging therapy to provide seizure control in patients with refractory epilepsy, although its therapeutic mechanisms remain elusive. Objective: We tested the hypothesis that ANT-DBS might interfere with the kindling process using three experimental groups: PTZ, DBS-ON and DBS-OFF. Methods: 79 male rats were used in two experiments and exposed to chemical kindling with pentylenetetrazole (PTZ, 30 mg/kg i.p.), delivered three times a week for a total of 18 kindling days (KD). These animals were divided into two sets of three groups: PTZ (n = 26), DBS-ON (n = 28) and DBS-OFF (n = 25). ANT-DBS (130 Hz, 90 μs, and 200 μA) was paired with PTZ injections, while DBS-OFF group, although implanted remained unstimulated. After KD 18, the first set of PTZ-treated animals and an additional group of 11 naïve rats were euthanized for brain extraction to study adenosine kinase (ADK) expression. To observe possible long-lasting effects of ANT stimulation, the second set of animals underwent a 1-week treatment and stimulation-free period after KD 18 before a final PTZ challenge. Results: ANT-DBS markedly attenuated kindling progression in the DBS-ON group, which developed seizure scores of 2.4 on KD 13, whereas equivalent seizure scores were reached in the DBS-OFF and PTZ groups as early as KD5 and KD6, respectively. The incidence of animals with generalized seizures following 3 consecutive PTZ injections was 94%, 74% and 21% in PTZ, DBS-OFF and DBS-ON groups, respectively. Seizure scores triggered by a PTZ challenge one week after cessation of stimulation revealed lasting suppression of seizure scores in the DBS-ON group (2.7 ± 0.2) compared to scores of 4.5 ± 0.1 for the PTZ group and 4.3 ± 0.1 for the DBS-OFF group (P = 0.0001). While ANT-DBS protected hippocampal cells, the expression of ADK was decreased in the DBS-ON group compared to both PTZ (P

Epilepsy is a chronic neurological disease characterized by recurrent behavioral seizures and affects approximately 1% of the global population. Epilepsy causes recurrent behavioral seizures, which are temporary behavioral changes caused by disordered, synchronized, and rhythmic activations of specific populations of neurons in the brain. Depressive disorders are one of the most common comorbid behavioral disorders in patients with epilepsy, yet they remain undiagnosed and untreated. The aim of the study is to investigate the severity of non-convulsive swimming and emotional behavior and mnemonic processes in rats with a kindling model of epilepsy under conditions of modulation of neurotransmitter systems of the caudate nuclei. It was found that in the dynamics of picrotoxin-induced kindling in rats, impaired swimming behavior, learning and memory abilities, as well as emotional dysfunctions, which are correlates of non-convulsive behavior, are recorded. It has been proven that the detected disorders of non-convulsive behaviors progressed in the dynamics of the formation of the kindling model of epilepsy and were maximal at the stages of completed kindling and postkindling. The obtained data demonstrate the key role of the striatum in the formation of non-convulsive behavioral disorders. On the 18th day, the pro-convulsive role of striatum is noted, which is confirmed by the enhancement of GABAergic and inhibition of dopaminergic neurotransmission of striatum along with the inhibition of its cholinergic mediation. The completion of the formation of kindling is confirmed by the enhancement of cholinergic and dopaminergic neurotransmission of striatum along with the inhibition of GABAergic mechanisms. In the postkindling stage, activation of cholinergic and dopaminergic neurotransmission of striatum and inhibition of its GABAergic activity are observed. The author considers the data obtained to be an experimental basis for the feasibility of testing clinical diagnostic effects in terms of dynamic monitoring of the behavior of patients with epilepsy during interictal periods, as well as possible corrective pharmacological effects in the case of modulation of the activity of certain neurotransmitter systems and intrastriatal neurotransmission.

Epilepsy is a prolonged, progressively advancing nervous and psychiatric disorder of various etiologies, characterized by paroxysmal and relatively persistent psychological disturbances. A significant burden of comorbid pathology is attributed to psychiatric disorders. Depressive disorders are among the most common behavioral comorbidities in patients with epilepsy, often remaining undiagnosed and untreated. The approach to treating depression in epilepsy patients is currently underdeveloped. To fully understand the prospects of the experimental framework for minimizing and/or eliminating depressive behavioral manifestations during the interictal period under conditions of chronic epileptogenesis, we conducted a series of studies to determine the effectiveness of comprehensive correction of non-seizure behavior in kindling animals. The aim of this study is to delineate alterations in the expression of non-seizure behavior in rats due to the combined administration of Vortioxetine with antiepileptic drugs in the dynamic context of chronic kindling-induced seizure activity. It has been established that in rats during the development of Picrotoxin-induced chronic epileptic syndrome, disruptions in late-tonic, emotional, and swimming types of behavior are observed, which are manifestations of non-seizure behavior. It has been proven that the combined administration of Valproic acid and Vortioxetine results in successful correction of the tested forms of behavior. Less effectiveness is observed with vortioxetine alone, and the least effectiveness is noted in a smaller number of investigated behavior types after valproic acid administration. The data demonstrate balancing systemic-antisynergistic relationships, the imbalance of which during the development of picrotoxin-induced chronic epileptic syndrome allows the development of non-seizure behavior forms during interictal periods. The obtained data and their analysis provide experimental groundwork for the appropriateness of clinically testing the combined administration of Vortioxetine with Valproic acid as part of complex therapy in epilepsy patients with the presence of a depressive behavioral component.

Treatment of epilepsy remains a major problem as some epileptic patients do not respond to the current therapeutics. Transient receptor potential ankyrin 1 (TRPA1) belongs to the TRP channels and has diverse physiological functions in the body. Considering its physiological properties, we aimed to evaluate its role in two experimental models of epilepsy, including pentylenetetrazol (PTZ)-induced acute seizure and PTZ-evoked kindling. Furthermore, the TRPA1 protein levels were assessed in the cerebral cortex, hippocampus, and cerebellum after seizure induction. Three groups of Wistar rats received acute intraperitoneal injection of pentylenetetrazol (PTZ, 85 mg/kg). The groups received intraventricular injections of vehicle (dimethyl sulfoxide, Tween 80, and sterile 0.9% saline), valproate (30 µg/rat), or HC030031 (TRPA1 antagonist, 14 µg/rat) before PTZ injection. In the PTZ-induced kindling model, PTZ was administrated 35 mg/kg every other day for 24 days. PTZ gradually provoked seizure-related behaviors. After experiments, the TRPA1 levels in the brain were assessed using western blot. The results showed that HC030031 reduced the median of seizure scores and S5 duration while increasing S2 and S5 latencies in acute and kindling models. The anticonvulsant effect of HC030031 was comparable with valproate as a standard anticonvulsant drug. Furthermore, induction of seizure, either acute or kindling, enhanced TRPA1 levels in the cerebral cortex, hippocampus, and cerebellum that were prevented by HC030031 or valproate administration. The results of this study showed that HC030031 as a TRPA1 receptor antagonist promoted a significant anticonvulsant effect comparable with valproate. Both drugs prevented TRPA1 upregulation during seizures. These findings imply that TRPA1 is a potential target in treating epilepsy. Highlights: TRPA1 antagonist blocked pentylenetetrazol-induced seizure. Pentylenetetrazol-kindled rats were protected by pretreatment with TRPA1 antagonist. Seizure enhanced TRPA1 expression in the cerebral cortex, hippocampus, and cerebellum. TRPA1 antagonist and valproate reduced elevated TRPA1 expression in the cerebral cortex, hippocampus, and cerebellum. [ABSTRACT FROM AUTHOR]

Aims: Deep brain electrical stimulation (DBS), as a potential therapy for drug resistive epileptic patients, has inhibitory action on epileptogenesis. In the present investigation, the role of dopamine D2‐like receptors in the antiepileptogenic action of DBS was studied. Methods: Seizures were induced in adult rats by stimulating the perforant path in a semi‐rapid kindling method. Five minutes after the last kindling stimulation, daily DBS was applied to the perforant path at the pattern of low frequency stimulation (LFS; 1 Hz; pulse duration: 0.1 ms; intensity: 50–150 μA; 4 trains of 200 pulses at 5 min intervals). Sulpiride (10 μg/1 μl, i.c.v.), a selective dopamine D2‐like receptor antagonist, was administered prior to the daily LFS application. Results: Kindling stimulations increased cumulative daily behavioral seizure stages, daily afterdischarge duration (dADD), and population spike amplitude (PS) in dentate gyrus following perforant path stimulation, while applying LFS decreased the kindled seizures' parameters. In addition, kindling potentiated the early (at 10–50 ms inter‐pulse interval) and late (at 150–1000 ms inter‐pulse interval) paired‐pulse inhibition and decreased the paired‐pulse facilitation (at 70–100 ms inter‐pulse interval). These effects were also inhibited by applying LFS. All inhibitory effects of LFS on kindling procedure were prevented by sulpiride administration. Conclusion: These data may suggest that LFS exerts its preventive effect on kindling development, at least partly, through the receptors on which sulpiride acts which are mainly dopamine D2‐like (including D2, D3, and D4) receptors. [ABSTRACT FROM AUTHOR]

Repeated seizures result in a persistent maladaptation of endocannabinoid (eCB) signaling, mediated part by anandamide signaling deficiency in the basolateral amygdala (BLA) that manifests as aberrant synaptic function and altered emotional behavior. Here, we determined the effect of repeated seizures (kindling) on 2-arachidonoylglycerol (2-AG) signaling on GABA transmission by directly measuring tonic and phasic eCB-mediated retrograde signaling in an in vitro BLA slice preparation from male rats. We report that both activity-dependent and muscarinic acetylcholine receptor (mAChR)-mediated depression of GABA synaptic transmission was reduced following repeated seizure activity. These effects were recapitulated in sham rats by preincubating slices with the 2-AG synthesizing enzyme inhibitor DO34. Conversely, preincubating slices with the 2-AG degrading enzyme inhibitor KML29 rescued activity-dependent 2-AG signaling, but not mAChR-mediated synaptic depression, over GABA transmission in kindled rats. These effects were not attributable to a change in cannabinoid type 1 (CB1) receptor sensitivity or altered 2-AG tonic signaling since the application of the highly selective CB1 receptor agonist CP55,940 provoked a similar reduction in GABA synaptic activity in both sham and kindled rats, while no effect of either DO34 or of the CB1 inverse agonist AM251 was observed on frequency and amplitude of spontaneous IPSCs in either sham or kindled rats. Collectively, these data provide evidence that repeated amygdala seizures persistently alter phasic 2-AG-mediated retrograde signaling at BLA GABAergic synapses, probably by impairing stimulus-dependent 2-AG synthesis/release, which contributes to the enduring aberrant synaptic plasticity associated with seizure activity. [ABSTRACT FROM AUTHOR]

Introduction: Some experimental data show that losartan can exert anticonvulsant activity; thereby it could create the potential therapy for treatment of epilepsy. However, there are limited and confusing data regarding the anticonvulsant action of losartan. The aim of this study was to answer the question why different studies found different effects of losartan on seizure and epilepsy. Materials and methods: The Sub convulsive doses (37.5 mg/kg) of pentylenetetrazol (PTZ) were administered (at intervals of one another day), to induce chemical kindling in conscious, free-moving rats. Separate groups of full kindled rats were pretreated with 12.5, 25, 50, 100 and 200 mg/kg doses of losartan. Results: The results showed although losartan had no significant effect on seizure stage, this drug induced a dose-dependent U-shaped effect on other seizure parameters. Conclusion: These results may explain the discrepancy reported about the effect of losartan on kindling model of epilepsy. [ABSTRACT FROM AUTHOR]

Introduction: Cognitive deficit is one of the common comorbidity accompanying epilepsy. The present study evaluated the effect of Celastrus paniculatus seed extract on seizure severity and cognitive deficit following the pentylenetetrazole (PTZ)-induced chemical kindling model. Methods: PTZ kindling model was developed by daily administration of the sub-convulsive dose of PTZ 30 mg/kg for four weeks. After four weeks of induction, the following treatment, namely sodium valproic acid (SVA) 200 mg/kg, C. paniculatus 500 mg\kg, pergolide 2 mg/ kg, C. paniculatus (250 mg\kg)+ Pergolide (1 mg/kg), and C. paniculatus (250 mg\kg)+ SVA (100 mg/kg) were administered 30 minutes prior to PTZ (30 mg/kg) injection for a period of next 14 days. Neurobehavioral parameters, including superoxide dismutase (SOD), Catalase (CAT), glutathione (GSH), and dopamine levels were assessed and the Morris water maze test (MWM) and Grip strength test (GPS) were performed. Hematoxylin & Eosin (H&E) staining of hippocampal cornu ammonis (CA1), CA2, CA3, dentate gyrus (DG), and frontal cortex was performed. Results: C. paniculatus (500 mg/kg) alone and in combination ( C. paniculatus (250 mg\ kg)+ pergolide (1 mg/kg) and C. paniculatus (250 mg\kg)+ SVA (100 mg/kg)) significantly (P<0.05) reduced the seizure score, mean latency time, and distance traveled in the MWM. However, no significant effect was seen in GPS. Biochemical analysis showed elevated antioxidant markers, namely GSH, CAT, and SOD, and also elevated dopamine levels. C. paniculatus and its combination also significantly (P<0.05) protected against neuronal loss in the hippocampus and frontal cortex evidenced by H&E staining Conclusion: C. paniculatus alone and in combination with other agents may have the potential to treat epilepsy and associated cognitive deficits [ABSTRACT FROM AUTHOR]

The Middle Stone Age deposits at Sibudu contain sedge (Cyperaceae) nutlets, which previously have been interpreted as indirect evidence of bedding. Scanning electron microscopy was used to identify the sedge nutlets through comparison of archaeological specimens with modern analogues. The presence of nutlets of Cladium mariscus (L.) Pohl subsp. jamaicense (Crantz) Kük, a 1–3 m tall sedge with long scabrid leaves, was unexpected and challenges the bedding hypothesis because of the minute sharp hairs along the midrib and margins of the leaf blades. Nevertheless, we argue for the use of Cladium as bedding material, possibly as the foundation on which softer matter was laid. It is possible that the Cladium nutlets and rhizomes may have been eaten and that the plant was also used as kindling or fuel. [ABSTRACT FROM AUTHOR]

The aim of the study is to determine the level of HIF-1α, TNF-α, and NF-kB in the hippocampus of kindled rats treated with rapamycin and axitinib. Materials and methods. Kindling was produced in 29 rats by administration of three-week pentylenetetrazole (PTZ, 35.0 mg/kg, i.p.). Treatment with rapamycin (0.5 mg/kg, i.p.) and axitinib (2.5 mg/kg, i.p.) was performed for ten days in fully kindled rats. The avidin-biotin-peroxidase method was used for hippocampal slice staining. For negative control, staining was performed using only secondary antibodies. Results. The HIF-1α expression increased in kindled rats raised by 1.77 times compared to the control (p<0.001). Axitinib treatment resulted in of HIF-1α level of 16.7 % (p<0.05) compared with kindled animals, while combined treatment with rapamycin and axitinib reduced HIF-1α by 33.8 % (p<0.01). In kindled rats, TNF-α expression was 3.74 times greater than in control (p<0.001). Rapamycin treatment reduced TNF-α by 31.0 % (p<0.01). Axitinib treatment caused a reduction of TNF-α by 21.1 % (p<0.05). Combined treatment with rapamycin and axitinib reduced TNF-α by 48.0 % (p<0.001) but still exceeded the TNF-α in control by 1.95 times (p<0.01). NF-kB level in kindled rats exceeded the control by three times (p<0.001). Rapamycin caused a reduction of 19.3 % (p>0.05), while axitinib - by 26.5 % (p<0.05) compared with kindled rats. Combined treatment with rapamycin and axitinib resulted in NF-kB reduction by 56.7 % compared with kindled rats (p<0.001). Conclusions. PTZ-kindling resulted in an increase in the immunoreactivity of HIF-1α, TNF-α, and NF-kB in the hippocampus. Combined treatment with rapamycin and axitinib engendered prevention of generalized seizures and normalized the level of HIF-1α and NF-kB with a significant reduction of TNF-α. Effects of treatment favours of synergy action of rapamycin and axitinib. [ABSTRACT FROM AUTHOR]

Growing studies indicate that vigilance states and circadian rhythms can influence seizure occurrence in patients with epilepsy and rodent models of epilepsy. Electrical kindling, referred to brief, repeated stimulations of a limbic structure, is a commonly used model of temporal lobe epilepsy. Kindling via the classic protocol lasting a few weeks does not generally induce spontaneous recurrent seizures (SRS), but extended kindling that applies over the course of a few months has shown to induce SRS in several animal species. Kindling-induced SRS in monkeys and cats were observed mainly during resting wakefulness or sleep, but the behavioral activities associated with SRS in rodent models of extended kindling remain unknown. We aimed to add information in this area using a mouse model of extended hippocampal kindling. Middle-aged C57 black mice experienced ≥80 hippocampal stimulations (delivered twice daily) and then underwent continuous 24 h electroencephalography (EEG)-video monitoring for SRS detection. SRS were recognized by EEG discharges and associated motor seizures. The five stages of the modified Racine scale for mice were used to score motor seizure severities. Seizure-preceding behaviors were assessed in a 3 min period prior to seizure onset and categorized as active and inactive. Three main observations emerged from the present analysis. (1) SRS were found to predominantly manifest as generalized (stage 3-5) motor seizures in association with tail erection or Straub tail. (2) SRS occurrences were not significantly altered by the light on/off cycle. (3) Generalized (stage 3-5) motor seizures were mainly preceded by inactive behaviors such as immobility, standing still, or apparent sleep without evident volitional movement. Considering deeper subcortical structures implicated in genesis of tail erection in other seizure models, we postulate that genesis of generalized motor seizures in extended kindled mice may involve deeper subcortical structures. Our present data together with previous findings from post-status epilepticus models support the notion that ambient cage behaviors are strong influencing factors of SRS occurrence in rodent models of temporal lobe epilepsy. [ABSTRACT FROM AUTHOR]

Hyssopus officinalis L. is one of the most important medicinal plants in traditional medicine used to treat seizures. In this study, we assessed the effects of H. officinalis hydroalcoholic extract against pentylenetetrazol (PTZ)-induced seizures in rat. The anti-seizure activity of the extract was assessed in three doses of 25, 50, and 100 mg/kg. Kindling was induced by intraperitoneal injection of PTZ (35 mg/kg) every 48 h, and H. officinalis extract was administered daily and behavioral tests performed. The possible involvement of GABA receptors in the extract activity was investigated using flumazenil. Tonic seizure threshold and mortality rate were measured following intraperitoneal injection of 60 mg/kg PTZ on the 14th day, following 14 days administration of H. officinalis hydroalcoholic extract. Blood and hippocampus samples were prepared to measure brain and serum antioxidant capacity, malondialdehyde (MDA), and nitric oxide (NO). Finally, the expression of GABA receptor gene in brain tissue was investigated. H. officinalis extract increased tonic seizure threshold and decreased mortality due to PTZ. Flumazenil, as a GABA receptor antagonist, reduced the tonic seizure threshold. Extract treatment significantly improved memory and learning, increased brain antioxidant capacity, decreased brain MDA and NO in kindled rats. It also increased GABA receptor gene expression in pre-treated groups compared to the negative control group. H. officinalis extract probably exerts potential antiepileptic effects through the GABAergic system. Also, H. officinalis extract has a supportive effect against hippocampal neuronal damage and improves memory and learning in kindled rats. [ABSTRACT FROM AUTHOR]

Phytocannabinoids beyond the Δ9-tetrahy-drocannabinol have shown anticonvulsive effects. Also, alkylamides from Echinacea purpurea have been proved as cannabinomimetics. We examined the effect of the hydroalcoholic root extract of E. purpurea on pentylenetetrazol (PTZ)-induced tonic–clonic seizures and kindling model of epileptogenesis and the involvement of CB2 receptors as the mediator of this effect. Male Wistar rats (200 ± 20 g) were used. Single intraperitoneal (i.p.) injection of PTZ (80 mg/kg) was used to induce tonic–clonic seizures. The kindling model of epileptogenesis was induced by daily injections of PTZ (37 mg/kg; i.p. for 15 days). Latency and duration of the stages were monitored for analysis. The hydroalcoholic root extract of E. purpurea was injected (i.p.) 20 min before seizure induction at the doses of 10, 50, 100 and 200 mg/kg. CB2 receptor antagonist SR144528 was injected (0.1 mg/kg; i.p.) 20 min before the Echinacea injection. In the tonic–clonic model, pretreatment with E. purpurea at the doses of 100 and 200 mg/kg significantly increased latencies to S2–S6, while it significantly decreased S6 duration and mortality rate. SR144528 injection before the injection of 100 mg/kg of E. purpurea significantly prevented the effects of the extract on S4–S6 latencies. In the kindling model, E. purpurea at the doses of 100 and 200 mg/kg significantly delayed epileptogenesis and decreased mortality rate, while SR144528 injection before the injection of 100 mg/kg of E. purpurea significantly blocked this effect of the extract. These findings revealed the anticonvulsive and antiepileptogenesis effects of the E. purpurea root extract, which can be mediated by CB2 receptors. [ABSTRACT FROM AUTHOR]

Abstract Objective Patients with temporal lobe epilepsy (TLE) frequently report debilitating comorbidities such as memory impairments, anxiety, and depression. An extensive neuronal network generates epileptic seizures and associated comorbidities, but a detailed description of this network is unavailable, which requires the generation of neuronal activation maps in experimental animals. Methods We recorded electrographic seizures from the hippocampi during a kindling‐evoked focal impaired awareness seizure with observed freezing, facial twitching, and involuntary head bobbing. We mapped seizure circuits activated during these seizures by permanently tagging neurons through activity‐induced immediate early genes, combined with immunohistochemical approaches. Results There was bilateral activation of circuits necessary for memory consolidation, including the hippocampal complex, entorhinal cortex, cingulate gyrus, retrosplenial cortex, piriform cortex, and septohippocampal complex in kindled animals compared with unstimulated awake behaving mice. Neuronal circuits in the ventral hippocampus, amygdala, and anterior cingulate cortex, which regulate the stress response of hypothalamic‐pituitary‐adrenal axis, were also markedly activated during a focal impaired awareness seizure. Significance This study highlights neuronal circuits preferentially activated during a focal awareness impaired seizure in a rodent model. Many of the seizure‐activated neuronal circuits are critical modulators of memory consolidation and long‐term stress/depression response. The hijack of these memory and depression regulatory systems by a focal seizure could account for the frequent reports of comorbidities such as memory impairment and depression in many TLE patients.

Epileptogenesis is a complex and not well understood phenomenon. Here, we explore the hypothesis that epileptogenesis could be “hijacking” normal memory processes, and how this hypothesis may provide new directions for epilepsy treatment. First, we review similarities between the hypersynchronous circuits observed in epilepsy and memory consolidation processes involved in strengthening neuronal connections. Next, we describe the kindling model of seizures and its relation to long-term potentiation model of synaptic plasticity. We also examine how the strengthening of epileptic circuits is facilitated during the physiological slow wave sleep, similarly as episodic memories. Furthermore, we present studies showing that specific memories can directly trigger reflex seizures. The neuronal hypersynchrony in early stages of Alzheimer's disease, and the use of anti-epileptic drugs to improve the cognitive symptoms in this disease also suggests a connection between memory systems and epilepsy. Given the commonalities between memory processes and epilepsy, we propose that therapies for memory disorders might provide new avenues for treatment of epileptic patients.

Growing studies indicate that vigilance states and circadian rhythms can influence seizure occurrence in patients with epilepsy and rodent models of epilepsy. Electrical kindling, referred to brief, repeated stimulations of a limbic structure, is a commonly used model of temporal lobe epilepsy. Kindling via the classic protocol lasting a few weeks does not generally induce spontaneous recurrent seizures (SRS), but extended kindling that applies over the course of a few months has shown to induce SRS in several animal species. Kindling-induced SRS in monkeys and cats were observed mainly during resting wakefulness or sleep, but the behavioral activities associated with SRS in rodent models of extended kindling remain unknown. We aimed to add information in this area using a mouse model of extended hippocampal kindling. Middle-aged C57 black mice experienced ≥80 hippocampal stimulations (delivered twice daily) and then underwent continuous 24 h electroencephalography (EEG)-video monitoring for SRS detection. SRS were recognized by EEG discharges and associated motor seizures. The five stages of the modified Racine scale for mice were used to score motor seizure severities. Seizure-preceding behaviors were assessed in a 3 min period prior to seizure onset and categorized as active and inactive. Three main observations emerged from the present analysis. (1) SRS were found to predominantly manifest as generalized (stage 3–5) motor seizures in association with tail erection or Straub tail. (2) SRS occurrences were not significantly altered by the light on/off cycle. (3) Generalized (stage 3–5) motor seizures were mainly preceded by inactive behaviors such as immobility, standing still, or apparent sleep without evident volitional movement. Considering deeper subcortical structures implicated in genesis of tail erection in other seizure models, we postulate that genesis of generalized motor seizures in extended kindled mice may involve deeper subcortical structures. Our present data together with previous findings from post-status epilepticus models support the notion that ambient cage behaviors are strong influencing factors of SRS occurrence in rodent models of temporal lobe epilepsy.

Anxiety is one of the most common comorbidities of epilepsy, which has major detrimental effects on the quality of life. Generalized anxiety disorder (GAD) associated with epilepsy has been receiving most attention. However, several other forms of anxiety reportedly present in patients with epilepsy, including panic disorder (PD). In this study, using an animal model of limbic epilepsy, we examined the interplay between epilepsy and panic-like behavior (PLB). Further, considering the high degree of comorbidity between depression on the one hand, and both epilepsy and PD on the other hand, we studied whether and how the presence of PLB in animals with epilepsy would affect their performance in depression-relevant tests. Fifty-day-old male Wistar rats were subjected to repeated alternating electrical stimulations of the basolateral amygdala (BLA) to induce kindling of limbic seizures, and the dorsal periaqueductal gray (DPAG) to induce panic-like episodes. Seizure susceptibility and panic reaction threshold were examined before the first and 24h after the last stimulation. At the end of the stimulations, the rats were examined in depression-relevant tests: saccharin preference test (SPT) for anhedonia and forced swimming test (FST) for despair/hopelessness. With regard to kindling, BLA+DPAG stimulation induced more profound increase of seizure susceptibility than BLA stimulation alone (evident as the reduction of the afterdischarge threshold and the increase of the afterdischarge duration). With regard to PLB, the BLA+DPAG stimulation exacerbated the severity of panic-like episodes, as compared with the DPAG stimulation alone. Basolateral amygdala stimulation alone had no effects on panic-like reactions, and DPAG stimulation alone did not modify kindling epileptogenesis. Combined stimulation of BLA and DPAG induced depressive-like behavioral impairments. This is the first experimental study showing bidirectional, mutually exacerbating effect of epilepsy and PLB, and the precipitation of depressive-like state by the epilepsy-PLB comorbidity.

Background: Individuals with Alzheimer's disease (AD) have a heightened risk of epilepsy. However, the underlying mechanisms are not well-understood., Objective: We aimed to elucidate the role of the glutamate-glutamine cycle in this mechanism and test the effect of ceftriaxone, a glutamate transporter-1 (GLT-1) enhancer, on seizure susceptibility in the Tg2576 mouse model of AD., Methods: First, we assessed expression levels of key proteins in the glutamate-glutamine cycle in Tg2576 ( n  = 7) and wild-type littermates ( n  = 7), and subsequently in the kindling model of epilepsy ( n  = 6) and sham ( n  = 6). Then, kindling susceptibility was assessed in three groups: 200 mg/kg ceftriaxone-treated Tg2576 (Tg-Ceft, n  = 9); saline-treated Tg2576 (Tg-Sal, n  = 9); and saline-treated wild-type (WT-Sal, n  = 15). Mice were treated for seven days before kindling, and seizure susceptibility compared between groups., Results: Protein levels of GLT-1 ( p  = 0.0093) and glutamine synthetase ( p  = 0.0016) were reduced in cortex of Tg2576 mice, compared to WT. Kindling increased GLT-1 (cortex: p  < 0.0001, hippocampus: p  = 0.0075), and glutaminase (cortex: p  = 0.0044) protein levels, compared to sham. Both Tg-Ceft and WT-Sal displayed Class IV seizures in response to the first stimulation ( p  > 0.99), while Tg-Sal displayed Class V seizure ( p  = 0.0212 versus WT-Sal). Seizure susceptibility of Tg-Ceft was not different from Tg-Sal ( p  > 0.05), and kindling rates did not differ between groups., Conclusions: Disruptions to key components of the glutamate-glutamine cycle are observed in models of AD and epilepsy. However, increasing GLT-1 through ceftriaxone treatment did not influence seizure susceptibility in Tg2576 mice, suggesting this is not an effective strategy to lower seizure susceptibility in AD, or a higher dosage is needed., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Objectives:This study was designed to determine the effects of Cichorium intybus (CI) on apoptosis and GABAA receptor density in the brains of rats in pentyleneterazole induced kindling.Methods:The rats were divided into three groups: Control group, pentylenetetrazol administered (PTZ) group, and PTZ+CI extract administered (PTZ+CI) group. Control group received only physiological saline (0.5 ml). PTZ (35 mg/kg) injected to the animals in the PTZ and PTZ+CI groups. The CI extract (200 mg/kg) was also administered to the PTZ+CI group. A 75 mg/kg challenge dose of PTZ was administrated to the PTZ treated groups, on the 12th injection.Results:A significant increase was found in the number of neurons expressing the GABAA receptor in the brain tissue (hippocampus and cerebral cortex) of the PTZ group when compared to the control. The density of GABAA receptor of the neurons in the cerebral cortex significantly increased in PTZ administered groups compared to the control. The number of apoptotic neurons was found non-significant between groups in the brain.Conclusion:CI treatment prolonged the onset of the first seizure activity and seizure latency at a convulsive dose, and kept the number of GABAA receptors close to that of the control in the hippocampus.

Background and Objective: Dentate gyrus (DG) has a high density of 5-HT1A receptors. It has neural nitric oxide synthase (nNOS), which is involved in neural excitability. The purpose of this study was to investigate the role of 5-HT1A receptors and nNOS of DG in perforant path kindling model of epilepsy. Material and Methods: To achieve this purpose, a receptor antagonist (WAY100635, 0.1 mg/kg, intracerebroventricular, i.c.v) and neuronal nitric oxide synthase inhibitor (7-NI, 15 mg/kg, intraperitoneal, i.p.) were injected during kindling aquisition. Adult male Wistar rats (280 ± 20 g) were used in this study Animals were kindled through the daily administration of brief electrical stimulations (10 stimulations per day) to the perforant pathway. Field potential recordings were performed for 20 min in DG beforehand. Additionally, glial fibrillary acidic protein (GFAP) expression rate in the DG was determined using immunohistochemistry as a highly specific marker for glia. Results: WAY100635 (0.1 mg/kg) significantly attenuated the kindling threshold compared to the kindled + vehicle group (P < 0.001). The co-administration of WAY100635 with 7-NI, exerted a significant anticonvulsive effect. Furthermore, the slope of field Excitatory Post Synaptic Potentials (fEPSP) at the end of 10 days in the kindled + 7-NI + WAY100635 group was significantly lower than in the kindled + vehicle group (P < 0.001). Furthermore, immunohistochemistry showed that the density of GAFP+ cells in the kindled + 7-NI + WAY100635 group was significantly higher than in the kindled + vehicle group (P < 0.001). Conclusion: Our data demonstrate that antagonists of 5-HT1A receptors have proconvulsive effects and that astrocyte cells are involved in this process, while nNOS has an inhibitory effect on neuronal excitability. [ABSTRACT FROM AUTHOR]

Deep brain stimulation (DBS) of the anterior nucleus of the thalamus (ANT) is an emerging therapy to provide seizure control in patients with refractory epilepsy, although its therapeutic mechanisms remain elusive. We tested the hypothesis that ANT-DBS might interfere with the kindling process using three experimental groups: PTZ, DBS-ON and DBS-OFF. 79 male rats were used in two experiments and exposed to chemical kindling with pentylenetetrazole (PTZ, 30 mg/kg i.p.), delivered three times a week for a total of 18 kindling days (KD). These animals were divided into two sets of three groups: PTZ (n = 26), DBS-ON (n = 28) and DBS-OFF (n = 25). ANT-DBS (130 Hz, 90 μs, and 200 μA) was paired with PTZ injections, while DBS-OFF group, although implanted remained unstimulated. After KD 18, the first set of PTZ-treated animals and an additional group of 11 naïve rats were euthanized for brain extraction to study adenosine kinase (ADK) expression. To observe possible long-lasting effects of ANT stimulation, the second set of animals underwent a 1-week treatment and stimulation-free period after KD 18 before a final PTZ challenge. ANT-DBS markedly attenuated kindling progression in the DBS-ON group, which developed seizure scores of 2.4 on KD 13, whereas equivalent seizure scores were reached in the DBS-OFF and PTZ groups as early as KD5 and KD6, respectively. The incidence of animals with generalized seizures following 3 consecutive PTZ injections was 94%, 74% and 21% in PTZ, DBS-OFF and DBS-ON groups, respectively. Seizure scores triggered by a PTZ challenge one week after cessation of stimulation revealed lasting suppression of seizure scores in the DBS-ON group (2.7 ± 0.2) compared to scores of 4.5 ± 0.1 for the PTZ group and 4.3 ± 0.1 for the DBS-OFF group (P = 0.0001). While ANT-DBS protected hippocampal cells, the expression of ADK was decreased in the DBS-ON group compared to both PTZ (P < 0.01) and naïve animals (P < 0.01). Our study demonstrates that ANT-DBS interferes with the kindling process and reduced seizure activity was maintained after a stimulation free period of one week. Our findings suggest that ANT-DBS might have additional therapeutic benefits to attenuate seizure progression in epilepsy. • PTZ kindling was used to explore disease-modifying effects of ANT-DBS in rats. • ANT-DBS reduced seizure susceptibility and epileptogenesis. • ANT-DBS reduced hippocampal expression of ADK. • The clinical utility of ANT-DBS goes beyond seizure control in epilepsy. [ABSTRACT FROM AUTHOR]

Photothermal therapy (PTT) has been approved clinically to ablate epileptogenic focus, while the clinical application of this approach is still hindered due to its limited selectivity and potential safety concerns related to extreme hyperthermia. Hypothermal PPT (HPTT) is a novel treatment modality employing mild hyperthermia to ablate abnormal cells, which has a distinctive advantage of minimal side effects on healthy tissues. The significantly elevated hydrogen peroxide (H2O2) concentration in the epileptogenic zone provides a suitable microenvironment for selective chemodynamic therapy (CDT), which utilizes the Fenton reaction of H2O2 and iron‐based nanomaterials to generate cytotoxic free radicals. Herein, the authors report proof‐of‐concept evidence that HPTT and CDT can be successfully integrated to ablate epileptogenic focus. A photothermal nanocatalyst ferrous disulfide nanoplatform is prepared for CDT of epilepsy. More importantly, the CDT efficacy is augmented by the second near‐infrared irradiation‐induced hyperthermia, leading to synergistic HPTT and CDT therapy. In vivo studies on pentylenetetrazole kindling epileptic rats show that the frequency and severity of epileptic attacks are remarkably suppressed after ablation of the epileptogenic focus. It is envisioned that this HPTT augmented CDT strategy may serve as a novel strategy for the treatment of focal epilepsy. [ABSTRACT FROM AUTHOR]

Traumatic brain injury (TBI) is one of the leading causes of death and disability in the population worldwide, with a broad spectrum of symptoms and disabilities. Posttraumatic hyperexcitability is one of the most common neurological disorders that affect people after a head injury. A reliable animal model of posttraumatic hyperexcitability induced by TBI which allows one to test effective treatment strategies is yet to be developed. To address these issues, in the present study, we tested human embryonic stem cell-derived neural stem cell (NSC) transplantation in an animal model of posttraumatic hyperexcitability in which the brain injury was produced in one hemisphere of immunodeficient athymic nude rats by controlled cortical impact, and spontaneous seizures were produced by repeated electrical stimulation (kindling) in the contralateral hemisphere. At 14 wk posttransplantation, we report human NSC (hNSC) survival and differentiation into all 3 neural lineages in both sham and injured animals. We observed twice as many surviving hNSCs in the injured versus sham brain, and worse survival on the kindled side in both groups, indicating that kindling/seizures are detrimental to survival or proliferation of hNSCs. We also replicated our previous finding that hNSCs can ameliorate deficits on the novel place recognition task,33 but such improvements are abolished following kindling. We found no significant differences pre- or post-kindling on the elevated plus maze. No significant correlations were observed between hNSC survival and cognitive performance on either task. Together these findings suggest that Shef6-derived hNSCs may be beneficial as a therapy for TBI, but not in animals or patients with posttraumatic hyperexcitability.

BackgroundInfectious encephalitides are most often associated with acute seizures during the infection period and are risk factors for the development of epilepsy at later times. Mechanisms of viral encephalitis-induced epileptogenesis are poorly understood. Here, we evaluated the contribution of viral encephalitis-associated inflammation to ictogenesis and epileptogenesis using a rapid kindling protocol in rats. In addition, we examined whether minocycline can improve outcomes of viral-like brain inflammation.MethodsTo produce viral-like inflammation, polyinosinic-polycytidylic acid (PIC), a toll-like receptor 3 (TLR3) agonist, was applied to microglial/macrophage cell cultures and to the hippocampus of postnatal day 13 (P13) and postnatal day 74 (P74) rats. Cell cultures permit the examination of the inflammation induced by PIC, while the in vivo setting better suits the analysis of cytokine production and the effects of inflammation on epileptogenesis. Minocycline (50 mg/kg) was injected intraperitoneally for 3 consecutive days prior to the kindling procedure to evaluate its effects on inflammation and epileptogenesis.ResultsPIC injection facilitated kindling epileptogenesis, which was evident as an increase in the number of full limbic seizures at both ages. Furthermore, in P14 rats, we observed a faster seizure onset and prolonged retention of the kindling state. PIC administration also led to an increase in interleukin 1β (IL-1β) levels in the hippocampus in P14 and P75 rats. Treatment with minocycline reversed neither the pro-epileptogenic effects of PIC nor the increase of IL-1β in the hippocampus in both P14 and P75 rats.ConclusionsHippocampal injection of PIC facilitates rapid kindling epileptogenesis at both P14 and P75, suggesting that viral-induced inflammation increases epileptogenesis irrespective of brain maturation. Minocycline, however, was unable to reverse the increase of epileptogenesis, which might be linked to its absence of effect on hippocampal IL-1β levels at both ages.

Recent evidence suggests that P-glycoprotein (P-gp) overexpression mediates hyperexcitability and is associated with epileptogenesis. Transcranial focal electrical stimulation (TFS) delays epileptogenesis and inhibits P-gp overexpression after a generalized seizure. Here, first we measured P-gp expression during epileptogenesis and second, we assessed if TFS antiepileptogenic effect was related with P-gp overexpression avoidance. Male Wistar rats were implanted in right basolateral amygdala and stimulated daily for electrical amygdala kindling (EAK), P-gp expression was assessed during epileptogenesis in relevant brain areas. Stage I group showed 85% increase in P-gp in ipsilateral hippocampus (p < 0.001). Stage III group presented 58% and 57% increase in P-gp in both hippocampi (p < 0.05). Kindled group had 92% and 90% increase in P-gp in both hippocampi (p < 0.01), and 93% and 143% increase in both neocortices (p < 0.01). For the second experiment, TFS was administrated daily after each EAK stimulation for 20 days and P-gp concentration was assessed. No changes were found in the TFS group (p > 0.05). Kindled group showed 132% and 138% increase in P-gp in both hippocampi (p < 0.001) and 51% and 92% increase in both cortices (p < 0.001). Kindled + TFS group presented no changes (p > 0.05). Our experiments revealed that progression of EAK is associated with increased P-gp expression. These changes are structure-specific and dependent on seizure severity. EAK-induced P-gp overexpression would be associated with neuronal hyperexcitability and thus, epileptogenesis. P-gp could be a novel therapeutical target to avoid epileptogenesis. In accordance with this, TFS inhibited P-gp overexpression and interfered with EAK. An important limitation of the present study is that P-gp neuronal expression was not evaluated under the different experimental conditions. Future studies should be carried out to determine P-gp neuronal overexpression in hyperexcitable networks during epileptogenesis. The TFS-induced lessening of P-gp overexpression could be a novel therapeutical strategy to avoid epileptogenesis in high-risk patients.

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