Conditional knockout of REST/NRSF in excitatory neurons reduces seizure susceptibility to chemical kindling

The repressor element-1 silencing transcription factor/neuron-restrictive silencer factor (REST/NRSF) is an epigenetic master regulator that plays a crucial role during nervous system development and maturation. REST function was originally described during development, where it determines neuronal phenotype. However, recent studies showed that REST participates in several processes in the adult brain, including neuronal plasticity and epileptogenesis. In this regard, the relationships between REST and epilepsy are still controversial and need further investigation. As forebrain excitatory neurons are the common final pathway of seizure susceptibility, we investigated the role of REST in epilepsy by inducing REST conditional knockout (REST-cKO) specifically in excitatory neurons of the hippocampus. To target the excitatory neuronal population, we cloned the calcium/calmodulin-dependent protein kinase IIα minimal promoter upstream of Cre recombinase. After assessing the specificity of the promoter's expression, the transgenes were packaged in an engineered adeno-associated virus able to cross the blood-brain and blood-cerebrospinal fluid barriers and delivered in the lateral ventricles of 2-month-old RESTflox/flox mice to characterize, after 1 month, the cognitive phenotype and the seizure propensity. We show that REST-cKO mice display lower levels of anxiety in the light-dark test with respect to control mice but have unaltered motor, social, and cognitive profiles. The evaluation of the susceptibility to epileptic seizures showed that REST-cKO mice are more resistant to pentylenetetrazole-induced kindling but not to seizures induced by a single administration of the convulsant and show higher survival rates. Overall, these data suggest that the absence of REST in forebrain excitatory neurons decreases seizure susceptibility, pointing to a pro-epileptogenic role of the transcriptional repressor under conditions of pathological excitation/inhibition imbalance.

Pyrus pashia fruit extract and its major phytometabolite chrysin prevent hippocampal apoptosis and memory impairment in PTZ-kindled mice

OBJECTIVES

Epilepsy is a chronic neurological condition with recurrent seizures. One-third of epilepsy patients experience unacceptable side effects from antiepileptic drugs. Pyrus pashia is a deciduous tree from southern Asia. Ethnomedicinally, Malakand tribes use its fruits for epilepsy treatment. Our prior research demonstrated the anticonvulsive properties of ethanolic extract of Pyrus pashia (EPP) and its bioactive compound chrysin in acute seizure tests. This study aims to investigate the impact of EPP and chrysin on cognitive impairment in a PTZ-induced kindling mice model of epilepsy.

METHODS

Swiss albino male mice were equally divided into four groups. The first group received 0.5% carboxy methyl cellulose dissolved in normal saline while the other three groups were pre-treated with Diazepam (DZP) (1 mg/kg, i.p.), EPP (200 mg/kg, p.o.) and chrysin (5 mg/kg, p.o.). After 30 min, all groups were administered PTZ (35 mg/kg, i.p.) and evaluated for seizure severity, cognitive function, and neuronal apoptosis. Western blot analysis was conducted to analyze the expressions of apoptosis biomarkers and memory-related genes, including cAMP response element-binding protein (CREB) and Brain Derived Neurotrophic Factor (BDNF).

RESULTS

The therapeutic effects of EPP and Chrysin were comparable to DZP in terms of reducing seizure severity, but unlike DZP, they prevented PTZ-induced memory impairment in experimental animals. Additionally, they increased the levels of BDNF and CREB while reducing apoptotic biomarkers in the hippocampus of experimental animals.

CONCLUSIONS

Based on the leads offered by this study EPP and its major bioactive constituent, could be developed as the treatment option for epilepsy.

Anti-inflammatory and antioxidative effects of elderberry diet in the rat model of seizure: a behavioral and histological investigation on the hippocampus

The present study was designed to evaluate whether elderberry (EB) effectively reduces inflammation and oxidative stress in hippocampal cells to modify seizure damage. Seizure was induced in rats by the injection of pentylenetetrazol (PTZ). In the Seizure + EB group, EB powder was added to the rats' routine diet for eight consecutive weeks. The study included several behavioral tests, immunohistopathology, Voronoi tessellation (to estimate the spatial distribution of cells in the hippocampus), and Sholl analysis. The results in the Seizure + EB group showed an improvement in the behavioral aspects of the study, a reduction in astrogliosis, astrocyte process length, number of branches, and intersections distal to the soma in the hippocampus of rats compared to controls. Further analysis showed that EB diet increased nuclear factor-like 2 expression and decreased caspase-3 expression in the hippocampus in the Seizure + EB group. In addition, EB protected hippocampal pyramidal neurons from PTZ toxicity and improved the spatial distribution of hippocampal neurons in the pyramidal layer and dentate gyrus. The results of the present study suggest that EB can be considered a potent modifier of astrocyte reactivation and inflammatory responses.

Effects of Rosmarinus officinalis L. Extract on Neurobehavioral and Neurobiological Changes in Male Rats with Pentylenetetrazol-Induced Epilepsy

This study investigated the effect of Rosmarinus officinalis L. (RO) extract on neurobehavioral and neurobiological changes in male rats with pentylenetetrazol (PTZ)-induced epilepsy. Rats were assigned into five groups: (1) control rats, (2) RO-treated rats, (3) PTZ-treated rats, (4) PTZ + RO-treated rats, and (5) PTZ + valproic acid (VA)-treated rats. The PTZ-treated rats required a significantly longer time and distance to find the platform in the Morris water maze test than the control and RO-treated rats. Additionally, PTZ-treated rats showed a decrease in tendency to cross over the platform compared to PTZ group. PTZ + RO-treated rats showed decreased swimming time and distance to find the platform compared to PTZ group. PTZ + RO-treated rats showed a significant decrease in seizure score, a reduced number of myoclonic jerks, and an increased onset of the first myoclonic jerk compared to PTZ group. PTZ reduced the time required to enter the dark room in the passive avoidance learning test, which was reversed by RO treatment. Biochemical results revealed that PTZ-treated rats had higher levels of oxidative stress markers. RO significantly increased the antioxidant markers levels and maintained normal rat brain histology. This study revealed that RO can shield the brain and neural tissues from PTZ.

Sphingosine 1-phosphate receptor 1 regulates blood-brain barrier permeability in epileptic mice

Destruction of the blood-brain barrier is a critical component of epilepsy pathology. Several studies have demonstrated that sphingosine 1-phosphate receptor 1 contributes to the modulation of vascular integrity. However, its effect on blood-brain barrier permeability in epileptic mice remains unclear. In this study, we prepared pilocarpine-induced status epilepticus models and pentylenetetrazol-induced epilepsy models in C57BL/6 mice. S1P1 expression was increased in the hippocampus after status epilepticus, whereas tight junction protein expression was decreased in epileptic mice compared with controls. Intraperitoneal injection of SEW2871, a specific agonist of sphingosine-1-phosphate receptor 1, decreased the level of tight junction protein in the hippocampus of epileptic mice, increased blood-brain barrier leakage, and aggravated the severity of seizures compared with the control. W146, a specific antagonist of sphingosine-1-phosphate receptor 1, increased the level of tight junction protein, attenuated blood-brain barrier disruption, and reduced seizure severity compared with the control. Furthermore, sphingosine 1-phosphate receptor 1 promoted the generation of interleukin-1β and tumor necrosis factor-α and caused astrocytosis. Disruption of tight junction protein and blood-brain barrier integrity by sphingosine 1-phosphate receptor 1 was reversed by minocycline, a neuroinflammation inhibitor. Behavioral tests revealed that sphingosine 1-phosphate receptor 1 exacerbated epilepsy-associated depression-like behaviors. Additionally, specific knockdown of astrocytic S1P1 inhibited neuroinflammatory responses and attenuated blood-brain barrier leakage, seizure severity, and epilepsy-associated depression-like behaviors. Taken together, our results suggest that astrocytic sphingosine 1-phosphate receptor 1 exacerbates blood-brain barrier disruption in the epileptic brain by promoting neuroinflammation.

Neuroprotective Effect of Morinda citrifolia on Behavioural and Biochemical Deficits in PTZ-induced Kindled Mice

INTRODUCTION

Epilepsy is a group of chronic neurological disorders characterized by seizures. Kindling, a chronic epileptic mouse model, was used to explore the epileptogenic mechanism and seek new anti-epileptics. In kindling, sub-convulsive (chemical/ electrical) stimuli were delivered repeatedly and erratically, eventually causing massive convulsions. Moreover, Morinda citrifolia (Noni) extracts are used as a remedy in ayurvedic preparations for many ailments. Noni has recently been shown to protect mice from amyloid beta-induced memory loss.

OBJECTIVE

This study was used to investigate the neuroprotective potential of Morinda citrifolia in mice over pentylenetetrazol (PTZ)-induced kindling seizure.

METHODS

Kindling was provoked by subsequent (one-day-gap) injections of PTZ (subconvulsive; 35 mg/kg; s.c.) for 29 days in mice. Following PTZ injection, convulsive behaviours were noted for 30 minutes. Open-field-test (locomotor activity), forced swimming test (depressive behaviors), elevated plus-maze, and passive avoidance tests were employed to evaluate cognition. Brain homogenate was used to estimate oxidative stress (glutathione, superoxide-dismutase, lipid-peroxidation) and acetylcholinesterase activity.

RESULTS

PTZ-provoked kindled mice displayed depressive behaviors, impaired locomotion, cognitive dysfunctions and various biochemical changes. However, treatment with Morinda citrifolia extract (500 and 1000 mg/kg, p.o) and valproic acid (200 mg/kg, p.o) before 60 min of each PTZ injection diminished kindling scores and restored behavioural, and biochemical changes.

CONCLUSION

Our findings suggest Morinda citrifolia offered neuroprotective effects against PTZinduced kindling seizures in mice, which were established by behavioural and biochemical paradigms.

Utilizing Andrographis paniculata leaves and roots by effective usage of the bioactive andrographolide and its nanodelivery: investigation of antikindling and antioxidant activities through in silico and in vivo studies

To valorise the bioactive constituents abundant in leaves and other parts of medicinal plants with the objective to minimize the plant-based wastes, this study was undertaken. The main bioactive constituent of Andrographis paniculata, an Asian medicinal plant, is andrographolide (AG, a diterpenoid), which has shown promising results in the treatment of neurodegenerative illnesses. Continuous electrical activity in the brain is a hallmark of the abnormal neurological conditions such as epilepsy (EY). This can lead to neurological sequelae. In this study, we used GSE28674 as a microarray expression profiling dataset to identify DEGs associated with andrographolide and those with fold changes >1 and p-value <0.05 GEO2R. We obtained eight DEG datasets (two up and six down). There was marked enrichment under various Kyoto Encyclopaedia of Genes and Genomes (KEGG) and Gene Ontology (GO) terms for these DEGs (DUSP10, FN1, AR, PRKCE, CA12, RBP4, GABRG2, and GABRA2). Synaptic vesicles and plasma membranes were the predominant sites of DEG expression. AG acts as an antiepileptic agent by upregulating GABA levels. The low bioavailability of AG is a significant limitation of its application. To control these limitations, andrographolide nanoparticles (AGNPs) were prepared and their neuroprotective effect against pentylenetetrazol (PTZ)-induced kindling epilepsy was investigated using network pharmacology (NP) and docking studies to evaluate the antiepileptic multi-target mechanisms of AG. Andrographolide is associated with eight targets in the treatment of epilepsy. Nicotine addiction, GABAergic synapse, and morphine addiction were mainly related to epilepsy, according to KEGG pathway enrichment analysis (p < 0.05). A docking study showed that andrographolide interacted with the key targets. AG regulates epilepsy and exerts its therapeutic effects by stimulating GABA production. Rats received 80 mg/kg body weight of AG and AGNP, phenytoin and PTZ (30 mg/kg i.p. injection on alternate days), brain MDA, SOD, GSH, GABAand histological changes of hippocampus and cortex were observed. PTZ injected rats showed significantly (^***p < 0.001) increased kindling behavior, increased MDA, decreased GSH, SOD, GABA activities, compared with normal rats, while treatment AGNPs significantly reduced kindling score and reversed oxidative damage. Finally, we conclude that the leaves and roots of A. Paniculata can be effectively utilized for its major bioactive constituent, andrographolide as a potent anti-epileptic agent. Furthermore, the findings of novel nanotherapeutic approach claim that nano-andrographolide can be successfully in the management of kindling seizures and neurodegenerative disorders.

Oleanolic acid suppresses pentylenetetrazole-induced seizure in vivo

The aim of this study was to investigate the protective effects of triterpene oleanolic acid on the brain tissue of mice with pentylenetetrazole (PTZ)-induced epileptic seizures. Male Swiss albino mice were randomly separated into five groups as the PTZ, control, and oleanolic acid (10, 30, and 100 mg/kg) groups. PTZ injection was seen to cause significant seizures compared with the control group. Oleanolic acid significantly prolonged the latency to onset of myoclonic jerks and the duration of clonic convulsions, and decreased mean seizure scores following PTZ administration. Pretreatment with oleanolic acid also led to an increase in antioxidant enzyme activity (CAT and AChE) and levels (GSH and SOD) in the brain. The data obtained from this study support oleanolic acid may have anticonvulsant potential in PTZ-induced seizures, prevent oxidative stress and protect against cognitive disturbances. These results may provide useful information for the inclusion of oleanolic acid in epilepsy treatment.

Zebrafish as an Innovative Tool for Epilepsy Modeling: State of the Art and Potential Future Directions

This article discusses the potential of Zebrafish (ZF) (Danio Rerio), as a model for epilepsy research. Epilepsy is a neurological disorder affecting both children and adults, and many aspects of this disease are still poorly understood. In vivo and in vitro models derived from rodents are the most widely used for studying both epilepsy pathophysiology and novel drug treatments. However, researchers have recently obtained several valuable insights into these two fields of investigation by studying ZF. Despite the relatively simple brain structure of these animals, researchers can collect large amounts of data in a much shorter period and at lower costs compared to classical rodent models. This is particularly useful when a large number of candidate antiseizure drugs need to be screened, and ethical issues are minimized. In ZF, seizures have been induced through a variety of chemoconvulsants, primarily pentylenetetrazol (PTZ), kainic acid (KA), and pilocarpine. Furthermore, ZF can be easily genetically modified to test specific aspects of monogenic forms of human epilepsy, as well as to discover potential convulsive phenotypes in monogenic mutants. The article reports on the state-of-the-art and potential new fields of application of ZF research, including its potential role in revealing epileptogenic mechanisms, rather than merely assessing iatrogenic acute seizure modulation.

Nrf2 is expressed more extensively in neurons than in astrocytes following an acute epileptic seizure in rats

The modulation of the nuclear factor erythroid 2-like 2 (Nrf2) activity has been reported to be implicated in the pathology of various neurological disorders, including epilepsy. Previous studies have demonstrated that Nrf2 is activated in the post-status epilepticus rat model; however, the spatiotemporal as well as cell type-specific expression of Nrf2 following brief epileptic seizures remains unclear. Here, we evaluated how an acute epileptic seizure affected the expression of Nrf2 and its downstream genes in the rats' cortex and the hippocampus up to 1 week following the induced seizure. We found that after a pentylenetetrazol-induced seizure, Nrf2 significantly increased at 24 h at the mRNA level and 3 h at the protein level in the cortex. In the hippocampus, the Nrf2 mRNA level peaked at 3 h after the seizure, and no significant changes were observed in the protein level. Interestingly, the mRNA level of Nrf2 downstream genes peaked at 3-6 h after seizure in both the cortex and the hippocampus. A significant increase in the expression of Nrf2 was observed in the neuronal population of CA1 and CA3 regions of the hippocampus, as well as in the cortex. Moreover, we observed no change in the co-localization of Nrf2 with astrocytes neither in the cortex nor in CA1 and CA3. Our results revealed that following a brief acute epileptic seizure, the expression of Nrf2 and its downstream genes is transiently increased and peaked at early timepoints after the seizure predominantly in the hippocampus, and this expression is restricted to the neuronal population.

Differential Pharmacokinetic Interplay of Atorvastatin on Lacosamide and Levetiracetam on Experimental Convulsions in Mice

BACKGROUND

The beneficial effects of statins, other than their hypocholesterolemia role, have been well documented, however, their use as an adjuvant drug with other antiseizure drugs, in the treatment of epilepsy is poorly understood.

OBJECTIVE

This study aimed to investigate the symbiotic effect of ATOR along with either lacosamide (LACO) or levetiracetam (LEVE) on experimentally induced epilepsy (Maximal electro-shock-MES or pentylenetetrazol- PTZ) in mice models.

METHODS

Conventional elevated-maze (EPM) and rotarod methods were performed to observe the behavioral effects.

RESULTS

In both the animal models, we found that co-administration of ATOR along with LACO showed a significant reduction in hind-limb extension (HLE) and clonic convulsion (CC) responses, respectively, but not in the ATOR+LEVE treated group. Intriguingly, comparable Straub tail response and myoclonic convulsion as the diazepam (DIA) group were observed only in the ATOR+LACO treated group. Moreover, a significant muscle-grip strength was observed in both groups. Also, pharmacokinetic analysis has indicated that the mean plasma concentration of ATOR peaked at 2nd hr in the presence of LACO but marginally peaked in the presence of LEVE. An Insilico study has revealed that ATOR has a higher binding affinity toward neuronal sodium channels.

CONCLUSION

This study has demonstrated that the plasma concentration of ATOR was potentiated in the presence of LACO, but not in the presence of LEVE and it has provided significant protection against both the electro and chemo-convulsive models in mice. This could be due to the symbiotic pharmacokinetic interplay of ATOR with LACO, and possibly, this interplay may interfere with sodium channel conductance.

Overexpression of Homer1b/c induces valproic acid resistance in epilepsy

AIMS

Resistance to valproic acid (VPA) is a major challenge for epilepsy treatment. We aimed to explore the mechanism underlying this resistance.

METHODS

Pentylenetetrazol-induced chronic epileptic rats were administered VPA (250 mg/Kg) for 14 days; rats with controlled seizure stages (seizure score14th-before  ≤0) and latent time (latent time14th-before  ≥0) were considered VPA-responsive, while the others were considered nonresponsive. Differentially expressed genes (DEGs) between the VPA-responsive and nonresponsive rat hippocampus transcriptomes were identified, and their functions were evaluated. The roles of postsynaptic density (PSD) and Homer1 were also determined. Furthermore, a subtype of Homer1 (Homer1b/c) was overexpressed or silenced in HT22 cells to determine its effect on VPA efficacy. Moreover, the membrane levels of mGluR1/5 directly bound to Homer1b/c were assessed.

RESULTS

Overall, 264 DEGs commonly enriched in the PSD between VPA-responsive and nonresponsive rats. Among them, Homer1 was more highly expressed in the hippocampus of nonresponses compared to that of responses. Overexpression of Homer1b/c interrupted VPA efficacy by increasing reactive oxygen species production, lactate dehydrogenase release, and calcium content. Furthermore, it induced the overexpression of mGluR1 and mGluR5.

CONCLUSION

Overexpression of Homer1b/c influenced VPA efficacy, revealing it could be a target to improve the efficacy of this treatment.

Anticonvulsive and anti-epileptogenesis effects of Echinacea purpurea root extract, an involvement of CB2 receptor

OBJECTIVES

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

These findings revealed the anticonvulsive and antiepileptogenesis effects of the E. purpurea root extract, which can be mediated by CB2 receptors.

Anticonvulsant Activity of Hydro Alcoholic Extract and Solvent Fractions of Biophytum umbraculum Welw. Syn (Oxalidaceae) Root in Mice

Background

Scientists and researchers continue to focus on medicinal plants as a potential source of lead chemicals in the search for and development of new antiepileptic medicines. Biophytum umbraculum Welw. Syn is used to treat epilepsy in Ethiopian traditional medicine. The anticonvulsant effect of Biophytum umbraculum Welw. Syn hydroalcoholic extract and solvent fractions was evaluated in this study since the claim has not been thoroughly explored.

Methods

The plant’s root was extracted using the maceration procedure, with aqueous, butanol, and chloroform as solvents. The maximum electroshock and pentylenetetrazol model tests were used to assess anticonvulsant activity. Mice were divided into five groups (n = 6) at random. The test groups received 100, 200, and 400 mg/kg of hydroalcoholic extract and solvent fraction, respectively. For the maximum electric shock test, the positive control groups received 25 mg/kg phenytoin and 200 mg/kg valproate for the pentylenetetrazol test. The negative control was given 10 mL/kg of pure water or 2% Tween 80.

Results

There were no signs of toxicity in the hydroalcoholic extract or solvent extraction. When compared to the negative control, the hydro-alcoholic extract had a significant anticonvulsant effect in both the maximum electric shock test and the pentylenetetrazol test. In both cases, the butanol component had a comparable impact. In the pentylenetetrazol test, the chloroform fraction had a significant anticonvulsant effect when compared to the control at dosages of MB200 and MB400. Flavonoids, phenols, tannins, steroids, terpenoids, and saponins were found in both the hydroalcoholic and solvent fractions of the plant extract.

Conclusion

The plant appears to have promising anticonvulsant properties, and it might be used to generate novel anti-epileptic drugs, according to this study.

Seizure Susceptibility and Sleep Disturbance as Biomarkers of Epileptogenesis after Experimental TBI

Objectives: We investigated whether seizure susceptibility increases over weeks−months after experimental traumatic brain injury (TBI), and whether seizure susceptibility in rats predicts the development of post-traumatic epilepsy (PTE) or epileptiform activity. We further investigated whether rats develop chronic sleep disturbance after TBI, and whether sleep disturbance parameters—alone or in combination with pentylenetetrazol (PTZ) test parameters—could serve as novel biomarkers for the development of post-traumatic epileptogenesis. Methods: TBI was induced in adult male Sprague-Dawley rats with lateral fluid-percussion injury. Sham-operated experimental controls underwent craniectomy without exposure to an impact force. Seizure susceptibility was tested with a PTZ test (30 mg/kg, intraperitoneally) on day (D) 30, D60, D90, and D180 after TBI (n = 28) or sham operation (n = 16) under video electroencephalogram (vEEG). In the 7th post-injury month, rats underwent continuous vEEG monitoring to detect spontaneous seizures and assess sleep disturbances. At the end of the experiments, rats were perfused for brain histology. Results: In the TBI group, the percentage of rats with PTZ-induced seizures increased over time (adjusted p < 0.05 compared with D30). Combinations of three PTZ test parameters (latency to the first epileptiform discharge (ED), number of EDs, and number of PTZ-induced seizures) survived the leave-one-out validation for differentiating rats with or without epileptiform activity, indicating an area under the receiver operating curve (AUC) of 0.743 (95% CI 0.472−0.992, p = 0.05) with a misclassification rate of 36% on D90, and an AUC of 0.752 (95% CI 0.483−0.929, p < 0.05) with a misclassification rate of 32% on D180. Sleep analysis revealed that the number of transitions to N3 or rapid eye movement (REM) sleep, along with the total number of transitions, was increased in the TBI group during the lights-on period (all p < 0.05). The sleep fragmentation index during the lights-on period was greater in the TBI rats than in sham-operated rats (p < 0.05). A combination of sleep parameters showed promise as diagnostic biomarkers of prior TBI, with an AUC of 0.792 (95% CI 0.549−0.934, p < 0.01) and a misclassification rate of 28%. Rats with epilepsy or any epileptiform activity had more transitions from N3 to the awake stage (p < 0.05), and the number of N3−awake transitions differentiated rats with or without epileptiform activity, with an AUC of 0.857 (95% CI 0.651−1.063, p < 0.01). Combining sleep parameters with PTZ parameters did not improve the biomarker performance. Significance: This is the first attempt to monitor the evolution of seizure susceptibility over months in a well-described rat model of PTE. Our data suggest that assessment of seizure susceptibility and sleep disturbance can provide diagnostic biomarkers of prior TBI and prognostic biomarkers of post-traumatic epileptogenesis.

Channa Striatus Protects Against PTZ-Induced Seizures in LPS Pre-conditioned Zebrafish Model

Epilepsy is a neurological disorder characterized by recurrent unprovoked seizures. Mounting evidence suggests the link between epileptogenesis and neuroinflammation. We hypothesize that eliminating neuroinflammation can alleviate seizure severity and prolong seizure onset. Channa striatus (CS) is a snakehead murrel commonly consumed by locals in Malaysia, believed to promote wound healing and mitigate inflammation. This study aims to unravel the anticonvulsive potential of CS extract on neuroinflammation-induced seizures using an adult zebrafish model. Neuroinflammation was induced via cerebroventricular microinjection of lipopolysaccharides from E. coli and later challenged with a second-hit pentylenetetrazol at a subconvulsive dose of 80 mg/kg. Zebrafish behaviour and swimming pattern analysis, as well as gene expression analysis, were done to study the pharmacological property of CS. CS extract pre-treatment in all doses significantly reduced seizure score, prolonged seizure onset time and slightly improved the locomotor swimming pattern of the zebrafish. CS extract pre-treatment at all doses significantly reduced the expression of NF_KB gene in the brain, and CS extract at 25 mg/L significantly reduced the IL-1 gene expression suggesting anti-neuroinflammatory properties. However, there were no significant changes in the TNFα. Besides, CS extract at 50 mg/L also elevated the expression of the CREB gene, which exerts neuroprotective effects on the neurons and the NPY gene, which plays a role in modulating the inhibition of the excitatory neurotransmission. To sum up, CS extract demonstrated some anticonvulsive and anti-inflammatory activity on neuroinflammation-induced seizures. Still, more studies need to be done to elucidate the mechanism of action of CS extract.

Continuous seizure emergency evoked in mice with pharmacological, electrographic, and pathological features distinct from status epilepticus

OBJECTIVES

Benzodiazepines are the standard of care for the management of sustained seizure emergencies, including status epilepticus (SE) and seizure clusters. Seizure clusters are a variably defined seizure emergency wherein a patient has multiple seizures above a baseline rate, with intervening periods of recovery, distinguishing clusters from SE. Although these seizure emergencies are phenotypically distinct, the precise pathophysiological and mechanistic differences between SE and seizure clusters are understudied. Emergency-specific preclinical models may differentiate the behavioral and pathological mechanisms that are acutely associated with seizure emergencies and seizure termination to better manage these events.

METHODS

Herein we characterize a novel model of sustained seizure emergency induced in CF-1 mice through the combined administration of high-dose phenytoin (PHT; 50 mg/kg, i.p.) and pentylenetetrazol (PTZ; 100 mg/kg, s.c.).

RESULTS

We presently describe a mouse model of sustained seizure emergency that is pathologically, pharmacologically, and behaviorally distinct from SE. Acute administration of PHT 1 h prior to PTZ led to significantly more mice with unremitting continuous seizure activity (CSA; 73.4%) vs vehicle-pretreated mice (13.8%; p < .0001). CSA was sensitive to lorazepam and valproic acid when administered at seizure onset and 30 minutes later. Carbamazepine worsened seizure control and post-CSA survival. Mice in CSA exhibited electroencephalography (EEG) patterns distinct from kainic acid-induced SE and PTZ alone, clearly differentiating CSA from SE and PTZ-induced myoclonic seizures. Neuropathological assessment by Fluoro-Jade C staining of brains collected 24 h post-CSA revealed no neurodegeneration in any mouse that underwent CSA, whereas there was widespread neuronal death in brains from KA-SE mice. Finally, immunohistochemistry revealed acute seizure-induced astrogliosis (glial fibrillary acid protein; GFAP) in hippocampal structures, whereas hippocampal neuronal nuclei (NeuN) protein expression was only reduced in KA-SE mice.

SIGNIFICANCE

We present a novel mouse model on which to further elucidate the mechanistic differences between sustained seizure emergencies (ie, SE and seizure clusters) to improve clinical interventions and define mechanisms of seizure termination.

Stimulatory and inhibitory effects of morphine on pentylenetetrazol-induced epileptic activity in rat

AIMS

The present study attempts to evaluate the effects of different doses of morphine on experimental epileptiform activity caused by pentylenetetrazol (PTZ) in rats.

METHODS

Thirty adult male rats were assigned to saline (n = 5), morphine (2, 5, and 10 mg/kg, n = 15), naloxone (1 mg/kg, n = 5), and pre-treated with naloxone+morphine (1 + 10 mg/kg, n = 5) groups. The animals were anesthetized with ketamine + xylazine (80 + 8 mg/kg), and then a bipolar electrode was implanted into the CA1 (AP: -2.76 mm, ML: -1.4 mm and DV: 3 mm). To evaluate the effects of drugs on spike count and their amplitudes by elab amplifier, after drug administration for 25 min, PTZ (80 mg/kg, i.p.) was injected to induce epileptiform activity. Finally, diazepam (10 mg/kg) was used to suppress epileptic activity.

RESULTS

The results revealed that morphine at a dose of 2 mg/kg decreased, and at doses of 5 and 10 mg/kg had an increasing effect on seizure-like events (SLEs). Nevertheless, morphine at a dose of 10 mg/kg enhanced SLEs significantly (p < 0.01). Naloxone at a dose of 1 mg/kg had no significant effect on the spike count but increased amplitude of them (p < 0.001). Moreover, being pretreatment with naloxone at a dose of 1 mg/kg, the morphine group showed significantly increased in the spike count (p < 0.05).

CONCLUSIONS

Morphine has biphasic effects on PTZ-induced epileptiform activities that way at a low dose has an inhibitory effect, but if the dose is increased, it will intensify the desired event and that the stimulatory effects of morphine appear not to be via opioid receptors.

Baicalin Rescues Cognitive Dysfunction, Mitigates Neurodegeneration, and Exerts Anti-Epileptic Effects Through Activating TLR4/MYD88/Caspase-3 Pathway in Rats

Purpose

This study aims to evaluate the beneficial effects of anti-epileptic mechanisms of baicalin (BA) on cognitive dysfunction and neurodegeneration in pentylenetetrazol (PTZ)-induced epileptic rats.

Methods

First, PTZ-induced epileptic rats were administered intraperitoneally a sub-convulsive dose of PTZ (40 mg/kg) daily, and the seizure susceptibility (the degree of seizures and latency) was evaluated using Racine’s criterion. Then, classical behavioral experiments were performed to test whether BA ameliorated cognitive dysfunction. Neurodegeneration was assessed using Fluoro Jade-B (FJB), and NeuN staining was used to determine whether BA offered a neuroprotective role. After BA had been proven to possess anti-epileptic effects, its possible mechanisms were analyzed through network pharmacology. Finally, the key targets for predictive mechanisms were experimentally verified.

Results

The epileptic model was successfully established, and BA had anti-epileptic effects. Epileptic rats displayed significant cognitive dysfunction, and BA markedly ameliorated cognitive dysfunction. Further, we also discovered that BA treatment mitigated neurodegeneration of the hippocampus CA3 regions, thereby ameliorated cognitive dysfunction of epileptic rats. Subsequent network pharmacology analysis was implemented to reveal a possible mechanism of BA in the anti-epileptic process and the TLR4/MYD88/Caspase-3 pathway was predicted. Finally, experimental studies showed that BA exerted an anti-epileptic effect by activating the TLR4/MYD88/Caspase-3 pathway in PTZ-induced epileptic rats.

Conclusion

In conclusion, BA had a protective effect against PTZ-induced seizures. BA improved cognitive dysfunction and exerted a neuroprotective action. The anti-epileptic effects of BA may be potentially through activation of the TLR4/MYD88/Caspase-3 pathway.

Inhibition of Death-associated Protein Kinase 1 protects against Epileptic Seizures in mice

Epilepsy is a chronic encephalopathy and one of the most common neurological disorders. Death-associated protein kinase 1 (DAPK1) expression has been shown to be upregulated in the brains of human epilepsy patients compared with those of normal subjects. However, little is known about the impact of DAPK1 on epileptic seizure conditions. In this study, we aim to clarify whether and how DAPK1 is regulated in epilepsy and whether targeting DAPK1 expression or activity has a protective effect against epilepsy using seizure animal models. Here, we found that cortical and hippocampal DAPK1 activity but not DAPK1 expression was increased immediately after convulsive pentylenetetrazol (PTZ) exposure in mice. However, DAPK1 overexpression was found after chronic low-dose PTZ insults during the kindling paradigm. The suppression of DAPK1 expression by genetic knockout significantly reduced PTZ-induced seizure phenotypes and the development of kindled seizures. Moreover, pharmacological inhibition of DAPK1 activity exerted rapid antiepileptic effects in both acute and chronic epilepsy mouse models. Mechanistically, PTZ stimulated the phosphorylation of NR2B through DAPK1 activation. Combined together, these results suggest that DAPK1 regulation is a novel mechanism for the control of both acute and chronic epilepsy and provide new therapeutic strategies for the treatment of human epilepsy.

Chemogenetic Activation of Feed-Forward Inhibitory Parvalbumin-Expressing Interneurons in the Cortico-Thalamocortical Network During Absence Seizures

Parvalbumin-expressing (PV+) interneurons are a subset of GABAergic inhibitory interneurons that mediate feed-forward inhibition (FFI) within the cortico-thalamocortical (CTC) network of the brain. The CTC network is a reciprocal loop with connections between cortex and thalamus. FFI PV+ interneurons control the firing of principal excitatory neurons within the CTC network and prevent runaway excitation. Studies have shown that generalized spike-wave discharges (SWDs), the hallmark of absence seizures on electroencephalogram (EEG), originate within the CTC network. In the stargazer mouse model of absence epilepsy, reduced FFI is believed to contribute to absence seizure genesis as there is a specific loss of excitatory α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) at synaptic inputs to PV+ interneurons within the CTC network. However, the degree to which this deficit is directly related to seizure generation has not yet been established. Using chemogenetics and in vivo EEG recording, we recently demonstrated that functional silencing of PV+ interneurons in either the somatosensory cortex (SScortex) or the reticular thalamic nucleus (RTN) is sufficient to generate absence-SWDs. Here, we used the same approach to assess whether activating PV+ FFI interneurons within the CTC network during absence seizures would prevent or reduce seizures. To target these interneurons, mice expressing Cre recombinase in PV+ interneurons (PV-Cre) were bred with mice expressing excitatory Gq-DREADD (hM3Dq-flox) receptors. An intraperitoneal dose of pro-epileptic chemical pentylenetetrazol (PTZ) was used to induce absence seizure. The impact of activation of FFI PV+ interneurons during seizures was tested by focal injection of the “designer drug” clozapine N-oxide (CNO) into either the SScortex or the RTN thalamus. Seizures were assessed in PV^Cre/Gq-DREADD animals using EEG/video recordings. Overall, DREADD-mediated activation of PV+ interneurons provided anti-epileptic effects against PTZ-induced seizures. CNO activation of FFI either prevented PTZ-induced absence seizures or suppressed their severity. Furthermore, PTZ-induced tonic-clonic seizures were also reduced in severity by activation of FFI PV+ interneurons. In contrast, administration of CNO to non-DREADD wild-type control animals did not afford any protection against PTZ-induced seizures. These data demonstrate that FFI PV+ interneurons within CTC microcircuits could be a potential therapeutic target for anti-absence seizure treatment in some patients.

Acid Sensing Ion Channel 2a Is Reduced in the Reduced Uterine Perfusion Pressure Mouse Model and Increases Seizure Susceptibility in Pregnant Mice

Eclampsia is diagnosed in pregnant women who develop novel seizures. Our laboratory showed that the reduced uterine perfusion pressure (RUPP) rat model of preeclampsia displays reduced latency to drug-induced seizures. While acid sensing ion channels (ASIC1a and 3) are important for reducing seizure longevity and severity, the role of ASIC2a in mediating seizure sensitivity in pregnancy has not been investigated. We hypothesized that 1) RUPP reduces hippocampal ASIC2a, and 2) pregnant mice with reduced ASIC2a (ASIC2a+/-) have increased seizure sensitivity. On gestational day 18.5, hippocampi from sham and RUPP C57BL/6 mice were harvested, and ASIC2a was assessed using Western blot. Pregnant wild-type and ASIC2a+/- mice received 40 mg/kg of pentylenetetrazol (i.p.) and were video recorded for 30 min. Behaviors were scored using a modified Racine scale (0-7: 0 = no seizure; 7 = respiratory arrest/death). Seizure severity was classified as mild (score = 1-3) or severe (score = 4-7). RUPP mice had reduced hippocampal and placental ASIC2a protein. ASIC2a+/- mice had reduced latency to seizures, increased seizure duration, increased severe seizure duration, and higher maximum seizure scores. Reduced hippocampal ASIC2a in RUPP mice and increased seizure activity in pregnant ASIC2a+/- mice support the hypothesis that reduced ASIC2a increases seizure sensitivity associated with the RUPP.

Effect of Memantine on Pentylenetetrazol-induced Seizures and EEG Profile in Animal Model of Cortical Malformation

Developmental cortical malformations (DCM) are one of the main causes of refractory epilepsy. Many are the mechanisms underlying the hyperexcitability in DCM, including the important contribution of N-methyl-D-aspartate receptors (NMDAR). NMDAR blockers are shown to abolish seizures and epileptiform activity. Memantine, a NMDAR antagonist used to treat Alzheimeŕs disease, has been recently investigated as a possible treatment for other neurological disorders. However, the effects on preventing or diminishing seizures are controversial. Here we aimed to evaluate the effects of memantine on pentylenetetrazole (PTZ)-induced seizures in the freeze-lesion (FL) model. Bilateral cortical microgyria were induced (FL) or not (Sham) in male Wistar neonate rats. At P30, subdural electrodes were implanted and 7 days later, video-EEG was recorded in animals receiving either memantine (FL-M or Sham-M) or saline (FL-S or Sham-S), followed by PTZ. Seizures were evaluated by video-EEG during one hour and scored according to Racine scale. The video-EEG analyses revealed that the number of seizures and the total duration of stage IV-V seizures developed during the 1 h-period increased after memantine application in all groups. The EEG power spectral density (PSD) analysis showed an increased PSD of pre-ictal delta in Sham-M animals and increased PSD of slow, middle and fast gamma oscillations after memantine injection that persists during the pre-ictal period in all groups. Our findings suggested that memantine was unable to control the PTZ-induced seizures and that the associated enhancement of PSD of gamma oscillations may contribute to the increased probability of seizure development in these animals.

LMR-101, a novel derivative of propofol, exhibits potent anticonvulsant effects and possibly interacts with a novel target on γ-aminobutyric acid type A receptors

OBJECTIVE

LMR-101 is a bisphenol derivative of propofol, a short-acting general anesthetic, which is also used to manage status epilepticus (SE). We evaluated the sedative and anticonvulsant effects of LMR-101 to discover its potential to manage epilepsy and SE in the clinic.

METHODS

Comparative studies between LMR-101 and propofol were performed in mice to elucidate an appropriate dose range for LMR-101 that produced anticonvulsant effects without significant sedation. Then, the anticonvulsive efficacy for LMR-101 was evaluated using seizure models induced by pentylenetetrazol and (+)-bicuculline. The ability of LMR-101 to inhibit SE was assessed using a rat model of SE induced by pilocarpine. Radioligand binding assay profiles for LMR-101 were performed to evaluate the potential mechanisms of action underlying its anticonvulsant properties.

RESULTS

In the mouse study, LMR-101 exhibited greater anticonvulsant and lesser sedative effect compared with propofol. LMR-101 completely inhibited pentylenetetrazol-induced seizures at a dose of 50 mg/kg and exhibited heavy sedation at 300 mg/kg. Propofol anesthetized all mice and only decreased the seizure rate at 25 mg/kg. LMR-101 also suppressed seizure behaviors evoked by (+)-bicuculline in mice in a dose-dependent manner. In the pilocarpine-induced SE model, LMR-101 significantly decreased the maximum seizure score and seizure duration in a dose-dependent manner. The median effective dose for LMR-101 was 14.30 mg/kg and 121.87 mg/kg to prevent and inhibit sustained SE, respectively. In binding assays, LMR-101 primarily inhibited tert-[³⁵ S] butylbicyclophosphorothionate binding to γ-aminobutyric acid type A (GABA_A ) receptors (half-maximal inhibitory concentration = 2.06 μmol·L^-1 ), but it did not affect [³ H] flunitrazepam or [³ H] muscimol binding.

SIGNIFICANCE

It is anticipated that LMR-101 might play an essential role in the clinical management of epilepsy and SE. LMR-101 also might bind to a novel target site on the GABA_A receptor that is different from existing antiepileptic drugs. Further study of the mechanisms of action of LMR-101 would be of considerable value in the search for new active drug sites on GABA_A receptors.

Long-lasting tagging of neurons activated by seizures or cocaine administration in Egr1-CreERT2 transgenic mice

Permanent tagging of neuronal ensembles activated in specific experimental situations is an important objective to study their properties and adaptations. In the context of learning and memory, these neurons are referred to as engram neurons. Here, we describe and characterize a novel mouse line, Egr1-CreER^T2 , which carries a transgene in which the promoter of the immediate early gene Egr1 drives the expression of the CreER^T2 recombinase that is only active in the presence of tamoxifen metabolite, 4-hydroxy-tamoxifen (4-OHT). Egr1-CreER^T2 mice were crossed with various reporter mice, Cre-dependently expressing a fluorescent protein. Without tamoxifen or 4-OHT, no or few tagged neurons were observed. Epileptic seizures induced by pilocarpine or pentylenetetrazol in the presence of tamoxifen or 4-OHT elicited the persistent tagging of many neurons and some astrocytes in the dentate gyrus of hippocampus, where Egr1 is transiently induced by seizures. One week after cocaine and 4-OHT administration, these mice displayed a higher number of tagged neurons in the dorsal striatum than saline/4-OHT controls, with differences between reporter lines. Cocaine-induced tagging required ERK activation and tagged neurons were more likely than others to exhibit ERK phosphorylation or Fos induction after a second injection. Interestingly neurons tagged in saline-treated mice also had an increased propensity to express Fos, suggesting the existence of highly responsive striatal neurons susceptible to be re-activated by cocaine repeated administration, which may contribute to the behavioral adaptations. Our report validates a novel transgenic mouse model for permanently tagging activated neurons and studying long-term alterations of Egr1-expressing cells.

Phyllathin From Phyllanthus Amarus Ameliorates Epileptic Convulsion and Kindling Associated Post-Ictal Depression in Mice via Inhibition of NF-κB/TLR-4 Pathway

Background

Epilepsy is a chronic, complex, unprovoked, and recurrent disorder of the nervous system that affected several people worldwide. Phyllanthus amarus (PA) has been documented to have neuroprotective potential.

Aim

To evaluate the potential of standardized extract of PA and its possible mechanism of action against the Pentylenetetrazol (PTZ)-induced convulsion and kindling associated post-ictal depression in experimental mice.

Materials and Methods

Phyllathin was isolated from methanolic extract of PA and well-characterized using HPTLC, ESI-MS/MS, and LC/MS. Phyllathin containing a standardized extract of PA (50, 100, and 200 mg/kg) was administered in convulsed and kindled mice, followed by an assessment of various parameters.

Results

The spectral analysis confirmed the molecular formula and weight of phyllanthin as C₂₄H₃₄O₆ and 418.2342 Da. PA (100 and 200 mg/kg) significantly ameliorated PTZ-induced (p < 0.05) duration, onset of tonic-clonic convulsion, and mortality in mice. It also significantly attenuated (p < 0.05) PTZ-induced kindling in mice. Alteration in brain GABA, dopamine, and glutamate, Na⁺K⁺ATPase, Ca⁺²-ATPase activities, and oxido-nitrosative stress in kindled mice was significantly restored (p < 0.05) by PA treatment. It also significantly (p < 0.05) down-regulated brain mRNA expressions of NF-κB, TNF-α, IL-1β, COX-2, and TLR-4. Histological aberrations induced by PTZ in the brain of a kindled rat was significantly (p < 0.05) ameliorated by PA.

Conclusion

Phyllanthin containing a standardized extract of PA exerts its antiepileptic potential via balancing excitatory (glutamate) and inhibitory (GABA) brain monoamines, voltage-gated ion channels (Na⁺K⁺/Ca⁺²-ATPase) and inhibition of NF-κB/TLR-4 pathway to ameliorate neuroinflammation (TNF-α, IL-1β, and COX-2) in experimental mice.

Investigating Cardiac Morphological Alterations in a Pentylenetetrazol-Kindling Model of Epilepsy

Epilepsy is a group of neurological disorders characterized by abnormal electrical activity in the central nervous system (CNS) and recurrent seizures representing the principal clinical manifestation. Sudden unexpected death in epilepsy (SUDEP) is the predominant cause of death in young epileptic patients. SUDEP patients displayed an increased cardiovascular (CV) risk, probably due to an impaired autonomic control of CV functions, but the underlying mechanisms need to be explored yet. Therefore, we aimed to examine the cardiac morphological alterations in a pentylenetetrazol (PTZ)-kindled rat model, a well-established tool for studying chronic epilepsy. To complete this, the distance between the atria, between the atrium and ventricle were measured, the heart was weighed, and the pathological morphology of dissected hearts was analyzed by histological assessment with hematoxylin and eosin staining. A significantly decreased distance between atria and a significant increase in heart weight were observed in PTZ-kindled rats which interestingly also displayed increased hemorrhagic content when compared with controls. Our findings provided evidence that changes in cardiac morphology may be related to autonomic CV dysfunctions occurring during SUDEP while also opening up more avenues to better develop novel drugs for the treatment of this disorder.

Ceftriaxone Treatment Affects EAAT2 Expression and Glutamatergic Neurotransmission and Exerts a Weak Anticonvulsant Effect in Young Rats

Epilepsy is a common neurological disorder. Despite the availability of a wide range of antiepileptic drugs, these are unsuccessful in preventing seizures in 20–30% of patients. Therefore, new pharmacological strategies are urgently required to control seizures. Modulation of glutamate uptake may have potential in the treatment of pharmacoresistant forms of epilepsy. Previous research showed that the antibiotic ceftriaxone (CTX) increased the expression and functional activity of excitatory amino acid transporter 2 (EAAT2) and exerted considerable anticonvulsant effects. However, other studies did not confirm a significant anticonvulsant effect of CTX administration. We investigated the impacts of CTX treatment on EAAT expression and glutamatergic neurotransmission, as well its anticonvulsant action, in young male Wistar rats. As shown by a quantitative real-time polymerase chain reaction (qPCR) assay and a Western blot analysis, the mRNA but not the protein level of EAAT2 increased in the hippocampus following CTX treatment. Repetitive CTX administration had only a mild anticonvulsant effect on pentylenetetrazol (PTZ)-induced convulsions in a maximal electroshock threshold test (MEST). CTX treatment did not affect the glutamatergic neurotransmission, including synaptic efficacy, short-term facilitation, or the summation of excitatory postsynaptic potentials (EPSPs) in the hippocampus and temporal cortex. However, it decreased the field EPSP (fEPSP) amplitudes evoked by intense electrical stimulation. In conclusion, in young rats, CTX treatment did not induce overexpression of EAAT2, therefore exerting only a weak antiseizure effect. Our data provide new insight into the effects of modulation of EAAT2 expression on brain functioning.

Galangin Prevents Increased Susceptibility to Pentylenetetrazol-Stimulated Seizures by Prostaglandin E2

Epilepsy is one of the most common chronic neurological diseases. It is characterized by recurrent epileptic seizures, where one-third of patients are refractory to existing treatments. Evidence revealed the association between neuroinflammation and increased susceptibility to seizures since there is a pronounced increase in the expression of key inflammatory mediators, such as prostaglandin E₂ (PGE₂), during seizures. The purpose of this study was to investigate whether PGE₂ increases susceptibility to pentylenetetrazol-induced (PTZ) seizures. Subsequently, we evaluated if the flavonoid isolated from the plant Piper aleyreanum (galangin) presented any anticonvulsive effects. Our results demonstrated that the group treated with PGE₂ increased susceptibility to PTZ and caused myoclonic and generalized seizures, which increased seizure duration and electroencephalographic wave amplitudes. Furthermore, treatment with PGE₂ and PTZ increased IBA-1 (microglial marker), GFAP (astrocytic marker), 4-HNE (lipid peroxidation marker), VCAM-1 (vascular cell adhesion molecule 1), and p-PKAIIα (phosphorylated cAMP-dependent protein kinase) immunocontent. Indeed, galangin prevented behavioral and electroencephalographic seizures, reactive species production, decreased microglial and astrocytic immunocontent, as well as decreased VCAM-1 immunocontent and p-PKA/PKA ratio induced by PGE₂/PTZ. Therefore, this study suggests galangin may have an antagonizing role on PGE₂-induced effects, reducing cerebral inflammation and protecting from excitatory effects evidenced by administrating PGE₂ and PTZ. However, further studies are needed to investigate the clinical implications of the findings and their underlying mechanisms.

High-performance counter-current chromatography isolation and initial neuroactivity characterization of furanocoumarin derivatives from Peucedanum alsaticum L (Apiaceae)

BACKGROUND

Medicinal plants are a proven source of drug-like small molecules with activity towards targets relevant for diseases of the central nervous system (CNS). Plant species of the Apiaceae family have to date yielded a number of neuroactive metabolites, such as coumarin derivatives with acetylcholinesterase inhibitory activity or anti-seizure activity.

PURPOSE

To accelerate the discovery of neuroactive phytochemicals with potential as CNS drug leads, we sought to rapidly isolate furanocoumarins, primary constituents of the dichloromethane (DCM) extract of the fruits of Peucedanum alsaticum L. (Apiaceae), using high-performance counter-current chromatography (HPCCC) and to evaluate their neuroactivity using both in vitro and in vivo microscale bioassays based on cholinesterase ELISAs and zebrafish epilepsy models.

RESEARCH METHODS AND PROCEDURE

In this study the DCM extract was subjected to HPCCC for the efficient separation (60 min) and isolation of furanocoumarins. Isolated compounds were identified with TOF-ESI-MS and NMR techniques and examined as inhibitors of AChE and BChE using ELISA microtiter assays. Anti-seizure properties of the extract and of the isolated compounds were evaluated using a zebrafish epilepsy model based on the GABA_A antagonist pentylenetetrazol (PTZ), which induces increased locomotor activity and seizure-like behavior.

RESULTS

The solvent system, composed of n-heptane, ethyl acetate, methanol and water (3:1:3:1, v/v/v/v), enabled the isolation of 2.63 mg lucidafuranocoumarin A (purity 98%) and 8.82 mg bergamottin (purity 96%) from 1.6 g crude DCM extract. The crude extract, at a concentration of 100 µg/ml, exhibited a weak inhibitory activity against acetylcholinesterase (AChE) (9.63 ± 1.59%) and a moderate inhibitory activity against butyrylcholinestrase (BChE) (49.41 ± 2.19%). Lucidafuranocoumarin A (100 µg/ml) was inactive against AChE but showed moderate inhibition towards BChE (40.66 ± 1.25%). The DCM extract of P. alsaticum fruits (0.62-1.75 µg/ml) and bergamottin (2-10 µm) exhibited weak anti-seizure activity, while lucidafuranocoumarin A (10-16 µm) was found to significantly inhibit PTZ-induced seizures. The percentage of seizure inhibition for the isolated compounds, at their most bioactive concentration, was 26% for bergamottin and 69% for lucidafuranocoumarin A.

CONCLUSION

Our findings underscore the utility of HPCCC for the rapid isolation of rare coumarin derivatives, and the potential of microscale in vivo bioassays based on zebrafish disease models for the rapid assessment of neuroactivity of these drug-like natural products.

Dietary Omega-3 Polyunsaturated Fatty Acid Deprivation Does Not Alter Seizure Thresholds but May Prevent the Anti-seizure Effects of Injected Docosahexaenoic Acid in Rats

Background: Brain concentrations of omega-3 docosahexaenoic acid (DHA, 22:6n-3) have been reported to positively correlate with seizure thresholds in rodent seizure models. It is not known whether brain DHA depletion, achieved by chronic dietary omega-3 polyunsaturated fatty acid (PUFA) deficiency, lowers seizure thresholds in rats.

Objective: The present study tested the hypothesis that lowering brain DHA concentration with chronic dietary n-3 PUFA deprivation in rats will reduce seizure thresholds, and that compared to injected oleic acid (OA), injected DHA will raise seizure thresholds in rats maintained on n-3 PUFA adequate and deficient diets.

Methods: Rats (60 days old) were surgically implanted with electrodes in the amygdala, and subsequently randomized to the AIN-93G diet containing adequate levels of n-3 PUFA derived from soybean oil or an n-3 PUFA-deficient diet derived from coconut and safflower oil. The rats were maintained on the diets for 37 weeks. Afterdischarge seizure thresholds (ADTs) were measured every 4–6 weeks by electrically stimulating the amygdala. Between weeks 35 and 37, ADTs were assessed within 1 h of subcutaneous OA or DHA injection (600 mg/kg). Seizure thresholds were also measured in a parallel group of non-implanted rats subjected to the maximal pentylenetetrazol (PTZ, 110 mg/kg) seizure test. PUFA composition was measured in the pyriform-amygdala complex of another group of non-implanted rats sacrificed at 16 and 32 weeks.

Results: Dietary n-3 PUFA deprivation did not significantly alter amygdaloid seizure thresholds or latency to PTZ-induced seizures. Acute injection of OA did not alter amygdaloid ADTs of rats on the n-3 PUFA adequate or deficient diets, whereas acute injection of DHA significantly increased amygdaloid ADTs in rats on the n-3 PUFA adequate control diet as compared to rats on the n-3 PUFA deficient diet (P < 0.05). Pyriform-amygdala DHA percent composition did not significantly differ between the groups, while n-6 docosapentaenoic acid, a marker of n-3 PUFA deficiency, was significantly increased by 2.9-fold at 32 weeks.

Conclusion: Chronic dietary n-3 PUFA deficiency does not alter seizure thresholds in rats, but may prevent the anti-seizure effects of DHA.

The Prophylactic and Therapeutic Effects of Saffron Extract and Crocin on Ethanol Withdrawal Syndrome in Mice

Objectives

Ethanol withdrawal following its chronic use is a serious outcome and challenging to treatment. The chronic use of ethanol induces a progressive neuroplasticity in different reigns of brain. In this study we evaluated the effects of aqueous extract of Crocus sativus L. (saffron) and its active compound, crocin, on the withdrawal behavior induced after repeated administration of ethanol, in two regimens of prophylactic (administration of drugs concomitant with the induction of dependence) and treatment (administration of drugs during the period of ethanol withdrawal) in mice which received ethanol.

Methods

Ethanol dependence was induced by oral administration of 10% v/v ethanol (2 g/kg) for 7 days. The aqueous extracts of saffron (40, 80 and 160) and crocin (10, 20 and 40 mg/kg) were administered to mice in two regimens of prophylactic (along with ethanol) and treatment (during withdrawal period). Diazepam (1 mg/kg) was used as a positive control. Six hours after discontinuation of the ethanol, seizure was evaluated by the sub-convulsive dose of pentyleneltetrazole (PTZ) (30 mg/kg). The open field test and Rota rod test were used for evaluation of locomotor activity and motor incoordination, respectively.

Results

Both extracts and crocin increased the number of crossed lined in the open field test. PTZ kindling seizure was inhibited in animals received extract (80 and 160 mg/kg) in both regimens. Motor incoordination was only improved following administration of crocin.

Conclusion

The aqueous extract of saffron and crocin can be considered as safe agents and reliable alternative to diazepam in management of ethanol withdrawal syndrome.

Seizure vulnerability and anxiety responses following chronic co-administration and acute withdrawal of caffeine and ethanol in a rat model

BACKGROUND

Caffeine antagonizes the intoxicating effects of alcohol. Consequently, there has been a dramatic global increase in the consumption of caffeinated drinks together with alcohol, especially among young adults. We assessed the seizure vulnerability and anxiety responses following the chronic co-administration of, and withdrawal from, caffeine and ethanol in male rats.

METHODS

The rats were randomly assigned to six groups consisting of 10 animals each: 10 mg/kg of caffeine, 20 mg/kg of caffeine, 4 g/kg of 20% ethanol, combined caffeine (20 mg/kg) and ethanol (4 g/kg of 20%), 4 mL/kg distilled water, and an untreated control group. The test substances were administered intragastrically twice daily for 29 days. On day 29, the rats were tested on the elevated plus maze to assess anxiety-related responses. On day 30, pentylenetetrazol (PTZ), a chemoconvulsant, was administered intraperitoneally at a dose of 40 mg/kg to the animals. Seizure responses and mortality up to 72 h were recorded.

RESULTS

Compared with the control group, the rats that received chronic treatment with low-dose caffeine, ethanol alone, and combined caffeine and ethanol exhibited significant anxiogenic-like effects, unlike with high-dose caffeine. Both low- and high-dose caffeine significantly increased PTZ seizure latency. Ethanol alone and combined caffeine and ethanol both lowered PTZ seizure latency. No significant difference occurred between the controls and the untreated group for either anxiety or seizure expression. Combined caffeine and ethanol increased the seizure-induced mortality from withdrawal effects at 72 h.

CONCLUSIONS

These findings suggest that the chronic co-administration of caffeine and ethanol and the acute withdrawal from these drugs lead to anxiogenic effects and increased seizure vulnerability.

Behavioral and Neurochemical Consequences of Pentylenetetrazol-Induced Kindling in Young and Middle-Aged Rats

(1) Objectives: Epilepsy disorder is likely to increase with aging, leading to an increased incidence of comorbidities and mortality. In spite of that, there is a lack of information regarding this issue and little knowledge of cognitive and emotional responses in aging subjects following epileptogenesis. We investigated whether and how aging distress epilepsy-related behavioral and biochemical outcomes are associated with cognition and emotion. (2) Methods: Young and middle-aged Wistar rats (3 or 12 months old) were treated with pentylenetetrazol (PTZ, 35 mg/kg) and injected on alternated days for 20 (young rats) and 32 days (middle-aged rats). Kindling was reached after two consecutive stages 4 plus one stage 5 or 6 in Racine scale. Control and kindled rats were evaluated in the elevated plus-maze (EPM) and object-recognition tests and their hippocampus was collected 24 h later for mitogen-activated protein kinases (MAPK) dosage. (3) Results: Middle-aged rats presented a higher resistance to develop kindling, with a decrease in the seizure severity index observed following the 4th and 9th PTZ injections. Middle-aged rats displayed an increased duration of the first myoclonic seizure and an increased latency to the first generalized seizure when compared to younger rats. The induction of kindling did not impair the animals’ performance (regardless of age) in the object-recognition task and the EPM test as well as it did not alter the hippocampal levels of MAPKs. (4) Significance: Our findings reveal that, despite age-related differences during epileptogenesis, middle-aged rats evaluated after kindling performed similarly during discriminative learning and emotional tasks in comparison to young animals, with no alteration of hippocampal MAPKs. Additional investigation must be carried out to explore the electrophysiological mechanisms underlying these responses, as well as the long-term effects displayed after kindling.

Effects of Nigella sativa on apoptosis and GABAA receptor density in cerebral cortical and hippocampal neurons in pentylenetetrazol induced kindling in rats

We investigated the effects of Nigella sativa on apoptosis and gamma-aminobutyric acid (GABA_A) receptor density in cerebral cortical and hippocampal neurons in a pentylenetetrazol (PTZ)-induced kindling model in rats. The PTZ kindling model was produced by injecting PTZ in subconvulsive doses to rats on days 1, 3, 5, 8, 10, 12, 15, 17, 19, 22 and 24 of the study into animals of PTZ treated (PTZ) and PTZ + N. sativa treated (PTZ + NS) groups. Clonic and tonic seizures were induced by injecting a convulsive dose of PTZ on day 26 of the study. Rats in the PTZ + NS group were treated also with a 10 mg/kg methanolic extract of N. sativa 2 h before each PTZ injection. Rats in the control group were treated with 4 ml/kg saline. The number of neurons that expressed GABA_A receptors in the hippocampus and cerebral cortex of rats in the PTZ and PTZ + NS groups increased significantly. There was no significant difference in the number of GABA_A receptors between the PTZ and PTZ + NS groups. GABA_A receptor density of the neurons in the cerebral cortex, but not hippocampus, was increased in PTZ group compared to controls. We observed a significant increase in the number of apoptotic neurons in the cerebral cortex of rats of both the PTZ and PTZ + NS groups compared to controls. We observed a significant decrease in the number of the apoptotic neurons in the cerebral cortex of rats in the PTZ + NS group compared to the PTZ group. N. sativa treatment ameliorated the PTZ induced neurodegeneration in the cerebral cortex as reflected by neuronal apoptosis and neuronal GABA_A receptor frequency.

Protective Effects of Otophylloside N on Pentylenetetrazol-Induced Neuronal Injury In vitro and In vivo

Approximately 30% of epileptic patients worldwide are medically unable to control their seizures. In addition, repeated epileptic seizures generally lead to neural damage. Pentylenetetrazol (PTZ) is a clinical circulatory and respiratory stimulant that is experimentally used to mimic epileptic convulsion in epilepsy research. Here, we systematically explore the neuroprotective effects of a pure compound isolated from Cynanchum otophyllum Schneid (Qingyangshen), Otophylloside N (OtoN), against PTZ-induced neuronal injury. We used three models: in vitro primary cortical neurons, in vivo mice, and in vivo zebrafish. Our results revealed that OtoN treatment may attenuate PTZ-induced morphology changes, cell death, LDH efflux in embryonic neuronal cells of C57BL/6J mice, and convulsive behavior in zebrafish. Additionally, our Western blot and RT-PCR results demonstrated that OtoN may attenuate PTZ-induced apoptosis and neuronal activation in neuronal cells, mice, and zebrafish. OtoN may reduce PTZ-induced cleavage of poly ADP-ribose polymerase and upregulation of the Bax/Bcl-2 ratio and decrease the expression level of c-Fos. This study is the first investigation of the neuroprotective effects of OtoN, which might be developed as a novel antiepileptic drug.

The involvement of neuronal nitric oxide synthase in the anti-epileptic action of curcumin on pentylenetetrazol-kindled rats

In this study, it was investigated whether a NO signaling pathway is involved in the anti-epileptic effect of curcumin on pentylenetetrazol (PTZ)-kindled rats. PTZ-kindled rats received different doses of curcumin that were administered intraperitoneally for 24 days. Either a non-selective inhibitor of nitric oxide synthase (NOS) (N-nitro-L-arginine methyl ester (L-NAME)), a selective inhibitor of neuronal NOS (7-Nitroindazole (7-NI)), a selective inhibitor of inducible NOS (aminoguanidine (AG)), or a NO precursor (L-arginine (L-ARG)) was administered chronically to evaluate the role of NO in curcumin's anti-seizure effect. A chronic administration of curcumin (200 mg/kg) was most effective for decreasing the mean frequency of epileptiform discharge. Furthermore, a pretreatment with L-NAME or 7-NI augmented the anti-epileptic effect of curcumin. In contrast, AG failed to significantly alter the anti-epileptic effect of curcumin. A pretreatment with L-ARG temporally reversed the anti-epileptic effect of curcumin in the early stage, but in the late stage, it potentiated curcumin's anti-epileptic effect. These findings suggest that the L-arginine-nitric oxide pathway may be involved in the anti-epileptic properties of curcumin, and that the role of nNOS (and not iNOS) is prominent in this neuroprotective feature.

Neuroprotective Effect of Lycopene Against PTZ-induced Kindling Seizures in Mice: Possible Behavioural, Biochemical and Mitochondrial Dysfunction

Oxidative stress and mitochondrial dysfunction are the major contributing factors in the pathophysiology of various neurological disorders. Recently, antioxidant therapies aimed at reducing oxidative stress gained a considerable attention in epilepsy treatment. Lycopene, a carotenoid antioxidant, has received scientific interest in recent years. So, the present study has been designed to evaluate the neuroprotective effect of lycopene against the pentylenetetrazol (PTZ)-induced kindling epilepsy. Laca mice received lycopene (2.5, 5 and 10 mg/kg) and sodium valproate for a period of 29 days and PTZ (40 mg/kg i.p (Intraperitoneal)) injection on alternative days. Various behavioural (kindling score), biochemical parameters (lipid peroxidation, superoxide dismutase, reduced glutathione, catalase and nitrite) and mitochondrial enzyme complex activities (I, II and IV) were assessed in the brain. Results depicted that repeated administration of a sub-convulsive dose of PTZ (40 mg/kg) significantly increased kindling score, oxidative damage and impaired mitochondrial enzyme complex activities (I, II and IV) as compared with naive animals. Lycopene (5 and 10 mg/kg) and sodium valproate (100 mg/kg) treatment for a duration of 29 days significantly attenuated kindling score, reversed oxidative damage and restored mitochondrial enzyme complex activities (I, II and IV) as compared with control. Thus, present study demonstrates the neuroprotective potential of lycopene in PTZ-induced kindling in mice.

Interference of TRPV1 function altered the susceptibility of PTZ-induced seizures

Transient receptor potential vanilloid 1 (TRPV1) is widely distributed in the central nervous system (CNS) including hippocampus, and regulates the balance of excitation and inhibition in CNS, which imply its important role in epilepsy. We used both pharmacological manipulations and transgenic mice to disturb the function of TRPV1 and then studied the effects of these alterations on the susceptibility of pentylenetetrazol (PTZ)-induced seizures. Our results showed that systemic administration of TRPV1 agonist capsaicin (CAP, 40 mg/kg) directly induced tonic-clonic seizures (TCS) without PTZ induction. The severity of seizure was increased in lower doses of CAP groups (5 and 10 mg/kg), although the latency to TCS was delayed. On the other hand, systemic administration of TRPV1 antagonist capsazepine (CPZ, 0.05 and 0.5 mg/kg) and TRPV1 knockout mice exhibited delayed latency to TCS and reduced mortality. Furthermore, hippocampal administration of CPZ (10 and 33 nmol/μL/side) was firstly reported to increase the latency to TCS, decrease the maximal grade of seizure and mortality. It is worth noting that decreased susceptibility of PTZ-induced seizures was observed in hippocampal TRPV1 overexpression mice and hippocampal CAP administration (33 nmol/μL/side), which is opposite from results of systemic agonist CAP. Our findings suggest that the systemic administration of TRPV1 antagonist may be a novel therapeutic target for epilepsy, and alteration of hippocampal TRPV1 function exerts a critical role in seizure susceptibility.

The involvement of neuronal nitric oxide synthase in antiepileptic action of alpha-asarone on pentylenetetrazol molding rats

The aim of the present study was to research the role of nitric oxide (NO) as a mediator of alpha (α)-asarone effect at the pentylenetetrazol (PTZ)-induced epileptiform discharge in rat. α-Asarone that was injected intraperitoneally twenty minutes before PTZ injection suppressed the clonic discharge effectively and the significant actions lasted for 30 min with no change of clonic amplitude. Administration of α-asarone did not influence interictal discharge. Four kinds of NO regulators were administered, including non-selective NG-nitro-L-arginine methyl ester (L-NAME), selective neuronal nitric oxide synthase (nNOS) inhibitor, 7-nitroindazole (7-NI), inducible nitric oxide synthase (iNOS) inhibitor, aminoguanidine (AG) and NO substrate, L-arginine (ARG) and their influence on the actions of α-asarone were studied, and all of the regulators were administered fifteen minutes before α-asarone injection. L-NAME and 7-NI reversed the anticlonic activity of α-asarone, and a significant increase of clonic activity was induced by L-NAME later in L-NAME +.α-asarone + PTZ group. There were no significant differences between AG + α-asarone + PTZ and α-asarone + PTZ group. L-ARG played a dual role in this study. It aggravated clonic discharge in the early stage but relieved interictal discharge in the late stage compared with PTZ group alone, and the beneficial effect of α-asarone was also reversed. All the above results suggest that nNOS/NO pathway mediates the anticonvulsant effect of α-asarone, and NO played a biphasic role in PTZ modeling process, while iNOS was unrelated to the inhibition effect of α-asarone on PTZ induced epileptiform activity.

Influence of pentylenetetrazol and NF-κB decoy oligodeoxynucleotides on p38 expression in neuron-like cells

The aim of this study was to investigate the effects of pentylenetetrazol (PTZ) and nuclear factor κ B (NF-κB) decoy oligodeoxynucleotides (ODNs) on p38 expression in neuron-like PC12 cells. In addition, the role of NF-κB activation in the pathogenesis of epilepsy was explored. p38 expression levels in control and PTZ-treated neuron-like PC12 cells were examined using western blotting. NF-κB decoy ODNs were transfected into the neuron-like PC12 cells using Lipofectamine 2000. NF-κB activation was investigated by confocal laser scanning microscopy (CLSM), and p38 expression levels were assessed using western blotting prior to and following transfection of decoy ODNs. Western blot analysis revealed that p38 levels in PTZ-treated neuron-like PC12 cells were significantly higher than those in control cells. CLSM demonstrated that the decoy ODNs inhibited NF-κB activation in neuron-like PC12 cells, and western blotting indicated that the decoy ODNs did not reduce p38 levels. The results of this study indicate that PTZ enhances p38 expression levels and activates NF-κB in PC12 cells. However, NF-κB does not modulate p38 expression levels.

Novel Vitamin K analogs suppress seizures in zebrafish and mouse models of epilepsy

Epilepsy is a debilitating disease affecting 1-2% of the world's population. Despite this high prevalence, 30% of patients suffering from epilepsy are not successfully managed by current medication suggesting a critical need for new anti-epileptic drugs (AEDs). In an effort to discover new therapeutics for the management of epilepsy, we began our study by screening drugs that, like some currently used AEDs, inhibit histone deacetylases (HDACs) using a well-established larval zebrafish model. In this model, 7-day post fertilization (dpf) larvae are treated with the widely used seizure-inducing compound pentylenetetrazol (PTZ) which stimulates a rapid increase in swimming behavior previously determined to be a measurable manifestation of seizures. In our first screen, we tested a number of different HDAC inhibitors and found that one, 2-benzamido-1 4-naphthoquinone (NQN1), significantly decreased swim activity to levels equal to that of valproic acid, 2-n-propylpentanoic acid (VPA). We continued to screen structurally related compounds including Vitamin K3 (VK3) and a number of novel Vitamin K (VK) analogs. We found that VK3 was a robust inhibitor of the PTZ-induced swim activity, as were several of our novel compounds. Three of these compounds were subsequently tested on mouse seizure models at the National Institute of Neurological Disorders and Stroke (NINDS) Anticonvulsant Screening Program. Compound 2h reduced seizures particularly well in the minimal clonic seizure (6Hz) and corneal-kindled mouse models of epilepsy, with no observable toxicity. As VK3 affects mitochondrial function, we tested the effects of our compounds on mitochondrial respiration and ATP production in a mouse hippocampal cell line. We demonstrate that these compounds affect ATP metabolism and increase total cellular ATP. Our data indicate the potential utility of these and other VK analogs for the prevention of seizures and suggest the potential mechanism for this protection may lie in the ability of these compounds to affect energy production.

Proconvulsant actions of intrahippocampal botulinum neurotoxin B in the rat

Botulinum neurotoxins (BoNTs) may affect the excitability of brain circuits by inhibiting neurotransmitter release at central synapses. There is evidence that local delivery of BoNT serotypes A and E, which target SNAP-25, a component of the release machinery specific to excitatory synapses, can inhibit seizure generation. BoNT serotype B (BoNT/B) targets VAMP2, which is expressed in both excitatory and inhibitory terminals. Here we assessed the effects of unilateral intrahippocampal infusion of BoNT/B in the rat on intravenous pentylenetetrazol (PTZ) seizure thresholds, and on the expression of spontaneous behavioral and electrographic seizures. Infusion of BoNT/B (500 and 1,000 unit) by convection-enhanced delivery caused a reduction in myoclonic twitch and clonic seizure thresholds in response to intravenous PTZ beginning about 6 days after the infusion. Handling-evoked and spontaneous convulsive seizures were observed in many BoNT/B-treated animals but not in vehicle-treated controls. Spontaneous electrographic seizure discharges were recorded in the dentate gyrus of animals that received local BoNT/B infusion. In addition, there was an increased frequency of interictal epileptiform spikes and sharp waves at the same recording site. BoNT/B-treated animals also exhibited tactile hyperresponsivity in comparison with vehicle-treated controls. This is the first demonstration that BoNT/B causes a delayed proconvulsant action when infused into the hippocampus. Local infusion of BoNT/B could be useful as a focal epilepsy model.

Effect of curcumin against pentylenetetrazol-induced seizure threshold in mice: possible involvement of adenosine A1 receptors

Curcumin, obtained from Curcuma longa, has been in use for manifold human disorders. The present study explores the effect of curcumin against pentylenetetrazol (PTZ) seizure threshold in mice. The possible involvement of adenosine receptor(s) mechanism was also investigated. Minimal dose of PTZ (i.v., mg/kg) needed to induce different phases of convulsions were recorded as an index of seizure threshold. Curcumin (20-120 mg/kg, p.o.) produced an increase in seizure threshold for convulsions induced by PTZ i.v. infusion. The anticonvulsant effect of curcumin (80 mg/kg) was prevented by 8-phenyltheophylline (0.5 mg/kg, i.p., non-selective adenosine receptor antagonist) and 8-cyclopentyl-1,3-dipropylxanthine (5 mg/kg, i.p., adenosine A1 receptor antagonist) but not by 8-(3-cholorostryl)caffeine (4 mg/kg, i.p., adenosine A2A receptor antagonist). Further, 5'-N-ethylcarboxamidoadenosine (0.005 mg/kg, i.p., non-selective A1 /A2 receptor agonist), or N(6) -cyclohexyladenosine (0.2 mg/kg, i.p., adenosine A1 receptor agonist), was able to potentiate the anticonvulsant action of curcumin. In contrast, 5'-(N-cyclopropyl) carboxamidoadenosine (0.1 mg/kg, i.p., adenosine A2A receptor agonist) failed to potentiate the effect of curcumin. This study demonstrated the anticonvulsant effect of curcumin against PTZ i.v. seizure threshold via a direct or indirect activation of adenosine A1 but not A2A receptors in mice. Thus, curcumin may prove to be an effective adjunct in treatment of convulsions.

Hyperexcitability and epileptic seizures in a model of frontotemporal dementia

Epileptic seizures are more common in patients with Alzheimer disease than in the general elderly population. Abnormal forms of hyperphosphorylated tau accumulate in Alzheimer disease and other tauopathies. Aggregates of tau are also found in patients with epilepsy and in experimental models of epilepsy. We report here the analysis of epileptic activity and neuropathological correlates of a transgenic line over-expressing human mutant tau, a model of frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17). The FTDP-17 model displays spontaneous epileptic activity and seizures with spike-wave complexes in the EEG, and a higher sensitivity to the GABAA receptor antagonist pentylenetetrazol (PTZ) when compared to age-matched controls, showing a notably increased seizure length and a shorter latency to develop severe seizures. FTDP-17 human tau mutants also display lower convulsive thresholds and higher lethality after PTZ injections. Astrocytosis and activated microglia are prominent in the hippocampus and other brain regions of young FTDP-17 mice where the human mutant tau transgene is expressed, before the appearance of hyperphosphorylated tau aggregates in these structures. FTDP-17 human mutant tau over-expression produces epilepsy and increased GABAA receptor-mediated hyperexcitability in the absence of Aβ pathology. Although aggregates of hyperphosphorylated tau have been observed in patients with epilepsy and in different chemically and electrically generated models of epilepsy, the FTDP-17 tau mutant analyzed here is the first model of genetically modified tau that presents with epilepsy. This model may represent a valuable tool to assay novel treatments in order to reduce tau pathology, a potential factor which may be involved in the development of epileptic seizures in dementia and other neurodegenerative diseases.

Responsive neurostimulation for the treatment of medically intractable epilepsy

With an annual incidence of 50/100,000 people, nearly 1% of the population suffers from epilepsy. Treatment with antiepileptic medication fails to achieve seizure remission in 20-30% of patients. One treatment option for refractory epilepsy patients who would not otherwise be surgical candidates is electrical stimulation of the brain, which is a rapidly evolving and reversible adjunctive therapy. Therapeutic stimulation can involve direct stimulation of the brain nuclei or indirect stimulation of peripheral nerves. There are three stimulation modalities that have class I evidence supporting their uses: vagus nerve stimulation (VNS), stimulation of the anterior nuclei of the thalamus (ANT), and, the most recently developed, responsive neurostimulation (RNS). While the other treatment modalities outlined deliver stimulation regardless of neuronal activity, the RNS administers stimulation only if triggered by seizure activity. The lower doses of stimulation provided by such responsive devices can not only reduce power consumption, but also prevent adverse reactions caused by continuous stimulation, which include the possibility of habituation to long-term stimulation. RNS, as an investigational treatment for medically refractory epilepsy, is currently under review by the FDA. Eventually systems may be developed to enable activation by neurochemical triggers or to wirelessly transmit any information gathered. We review the mechanisms, the current status, the target options, and the prospects of RNS for the treatment of medically intractable epilepsy.

Evaluation of Antiseizure Activity of Essential Oil from Roots of Angelica archangelica Linn. in Mice

In the present study, the effect of essential oil of the root of Angelica archangelica Linn. was evaluated against electrically and chemically induced seizures. The seizures were induced in mice by maximal electroshock and pentylenetetrazol. The effect of essential oil of the root of Angelica archangelica on seizures was compared with standard anticonvulsant agents, phenytoin and diazepam. The essential oil of the root of Angelica archangelica suppressed duration of tonic convulsions and showed recovery in maximal electroshock induced seizures while it delayed time of onset of clonic convulsions and showed mortality protection in pentylenetetrazol induced seizures. The essential oil of the root of Angelica archangelica also produced motor impairment at the antiseizure doses. The study indicated that the essential oil exhibited antiseizure effect. The antiseizure effect may be attributed to the presence of terpenes in the essential oil.

Passiflora incarnata L. (Passionflower) extracts elicit GABA currents in hippocampal neurons in vitro, and show anxiogenic and anticonvulsant effects in vivo, varying with extraction method

Potential mechanisms of Passiflora incarnata extracts and the effect of extraction methods on ingredients and biological effects were explored. Using the same batch of plant material, total flavonoid yields as measured by high-performance liquid chromatography coupled to diode array detection (HPLC-DAD) increased substantially with hot versus cold extraction methods. Whole Passiflora extract induced prominent, dose-dependent direct GABA(A) currents in hippocampal slices, but the expected modulation of synaptic GABA(A) currents was not seen. GABA was found to be a prominent ingredient of Passiflora extract, and GABA currents were absent when amino acids were removed from the extract. Five different extracts, prepared from a single batch of Passiflora incarnata, were administered to CF-1 mice for 1 week in their drinking water prior to evaluation of their behavioral effects. Anticonvulsant effects against PTZ-induced seizures were seen in mice that received 2 of the 5 Passiflora extracts. Instead of the anxiolytic effects described by others, anxiogenic effects in the elevated plus maze were seen in mice receiving any of the 5 Passiflora extracts.

Pentylenetetrazol produces a state-dependent conditioned place aversion to alcohol withdrawal in mice

The purpose of this study was to determine if aversive effects of alcohol withdrawal could be detected in mice using the place conditioning procedure and whether the GABA(A) receptor antagonist, pentylenetetrazol (PTZ), would increase the aversive effects of alcohol withdrawal and increase the probability of detecting conditioned place aversion. Subjects were alcohol-naïve mice from a specific line selectively bred for low alcohol preference (LAP1; n=91) and were assigned to three groups: alcohol withdrawal, PTZ alone, and PTZ+alcohol withdrawal. On four trials, mice received either a 4.0 g/kg intraperitoneal (i.p.) injection of alcohol (alcohol withdrawal, PTZ+alcohol withdrawal groups) or saline (PTZ group) 8 h prior to being placed on a distinctive floor texture for a 30-min conditioning session. Five minutes before these sessions, mice in the PTZ and PTZ+alcohol withdrawal groups received PTZ (5.0 mg/kg; i.p.) and the alcohol withdrawal group received saline. On intervening days mice received two saline injections at the same time points prior to being placed on a different floor texture. Post-conditioning floor preference was assessed in two 60-min tests; the first test was drug-free and the second test was state-dependent. Neither alcohol withdrawal nor PTZ produced significant place conditioning. The PTZ+alcohol withdrawal group showed a significant place aversion during the state-dependent test. These data suggest that the combined stimulus properties of PTZ and alcohol withdrawal facilitated the expression of conditioned place aversion to alcohol withdrawal.

Estrogen increases latencies to seizures and levels of 5alpha-pregnan-3alpha-ol-20-one in hippocampus of wild-type, but not 5alpha-reductase knockout, mice

Sex steroids can influence seizures. Estrogen (E(2)), progesterone (P(4)), and its metabolite, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP), in particular, have received much attention for exerting these effects. Typically, it is thought that E(2) precipitates seizures, and progestogens, such as P(4) and 3alpha,5alpha-THP, attenuate seizures. However, E(2) may also have antiseizure effects, perhaps in part through its enhancement of the formation of 3alpha,5alpha-THP, which has GABA(A)/benzodiazepine receptor agonist-like actions. To test this hypothesis, male and female, castrated or ovariectomized, wild-type and 5alpha-reductase knockout mice were implanted with Silastic capsules of E(2) or vehicle and then administered pentylenetetrazol (85 mg/kg, ip). Wild-type, but not 5alpha-reductase knockout, mice administered E(2) had significantly longer latencies to myoclonus and increased levels of 3alpha,5alpha-THP in the hippocampus. Thus, some of the anticonvulsive effects of E(2) may involve formation of 3alpha,5alpha-THP in the hippocampus.