Anticonvulsant effects of Cymbopogon giganteus extracts with possible effects on fully kindled seizures and anxiety in experimental rodent model of mesio-temporal epilepsy induced by pilocarpine

ETHNOPHARMACOLOGICAL RELEVANCE

Epilepsy is a neurological disorder of the brain characterized by periodic and unpredictable occurrence of a transient behavior alteration due to the rhythmic, synchronous and disordered firing of brain neuron. Worldwide, approximately 50 million people currently live with epilepsy and close to 80% of people with epilepsy live in poor countries. However, it was noticed in many countries worldwide that people with epilepsy and their families suffer from stigma and discrimination and that situation exposes them to high psychological conditions such as depression and anxiety as well as more physical problems including bruising and fractures from injuries related to seizures. However, several plants-based products used for epilepsy and anxiety treatments in different system of folk medicine have exhibited a significant anti-epileptic and antianxiety activities using animal models with fewer side effects.

AIM OF THE STUDY

The study aimed at evaluating the antiepileptic, status post-epilepticus and anxiolytic effects of Cymbopogon giganteus decoction in rat model induced by pilocarpine.

MATERIALS AND METHODS

A total of 90 rats were partitioned into 7 groups and treated as follow: animals of groups I (normal control) and II (considered the negative control) received distilled water (10 mL/kg); while groups III, IV, V, and VI were treated with the C. giganteus extract at 34, 85, 170 and 340 mg/kg p.o, respectively; and the group VII (considered positive control) received sodium valproate at 300 mg/kg, i.p. After 40 min post-treatment, a single dose of n-methyl-scopolamine (1 mg/kg, i.p) was administered to animals of groups (II, III, IV, V, VI, VII) followed by pilocarpine (360 mg/kg, i.p). Animal of group I (normal group) received distilled water. Rats were further observed for 6 h to evaluate the severity and the duration of the acute seizures of epilepsy according to Racine scale. Anxious behavior status post-epilepticus was also assessed in the same rats used above in the Elevated Plus Maze and number of entries into the open or closed arms and the time spent on either open or closed arms of the platform were recorded. Animals were also evaluated on Open Field Test and the number of rearing, crossing, grooming, defecation and center time were registered.

RESULTS

C. giganteus decoction significantly (P < 0.05) reduced the animal mortality, the number and duration of convulsions and effectively increased the latency of convulsions. The plant extract significantly (P < 0.05) improved GSH level and SOD activity, reduced MDA and CAT activity, increased GABA level and decreased GABA-t activity in hippocampus. The anxiety induced by pilocarpine was also significantly (P < 0.05) inhibited by the extract of the plant.

CONCLUSIONS

Thus, C. giganteus has demonstrated its antiepileptic and anxiolytic activities in rat model and may be used as preventive measure for patients suffering from epilepsy seizures and anxiety.

Pergularia daemia hydro-ethanolic extract protects against pentylenetetrazole kindling-induced seizures, oxidative stress, and neuroinflammation in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Current antiepileptic drugs fail to control approximately 30% of epilepsies. Therefore, there is a need to develop more effective antiepileptic drugs, and medicinal plants provide an attractive source for new compounds. Pergularia daemia (Asclepiadaceae) is used in Cameroon traditional medicine to treat stroke, anemia, inflammation, and epilepsy. Recently, traditional healers claim that an hydro-ethanolic extract of the roots of P. daemia is more effective than an aqueous extract on refractory seizures.

AIM OF THE STUDY

The antiepileptic effect of P. daemia hydro-ethanolic extract was investigated on the pentylenetetrazole kindling model of temporal lobe epilepsy in mice and possible mechanisms of action.

MATERIALS AND METHODS

Mice were divided into 8 groups treated as follows: normal group received distilled water (10 ml/kg, p.o.), control group received distilled water (10 ml/kg, p.o.), ethanol group received ethanol (5%, p.o.), positive control received sodium valproate (300 mg/kg, p.o.), and test groups received P. daemia hydro-ethanolic (HE) extract (1.6, 4, 8 and 16 mg/kg, p.o.). All groups were kindled by 11 injections of pentylenetetrazole (PTZ) (35 mg/kg, i.p.), once every alternate day (48 ± 2 h), until the development of kindling, i.e., the occurrence of stage 5 seizures for two consecutive trials. One week later, i.e., 29^th day, mice were challenged with a single and lower dose of PTZ (25 mg/kg, i.p.) that does not induce seizures in normal mice but causes seizures in mice prone to seizures and behavioral alterations. After completion of the kindling procedure, Morris water maze, passive avoidance, and open field tests were performed. Afterward, animals were euthanized, and hippocampi were removed for the estimation of the levels of GABA-transaminase (GABA-T), L-glutamate decarboxylase (L-GAD), and γ-aminobutyric acid (GABA). Oxidative stress and neuroinflammation markers also were quantified. Finally, histological analysis of the hippocampus was carried out.

RESULTS

PTZ-kindling induced myoclonic jerks and generalized tonic-clonic seizures in control mice. However, the HE extract of P. daemia (4-16 mg/kg), compared to sodium valproate, significantly protected mice against myoclonic jerks and generalized tonic-clonic seizures. Also, the HE extract (1.6-16 mg/kg) significantly increased the seizure score. Furthermore, the HE extract of P. daemia significantly reduced seizure-induced cognitive impairments. PTZ-kindling induced significant alterations in GABA, GABA-T, and L-GAD contents as well as oxidative stress, and neuroinflammation, and the HE extract significantly reversed these effects, suggesting possible mechanisms. All these activities of the HE extract were confirmed by its protective effect against neuronal loss in the hippocampus.

CONCLUSIONS

The HE extract of P. daemia protected mice against kindled seizures and cognitive impairments, and these effects were greater than those of sodium valproate, a widely used antiepileptic drug. These effects may be mediated by neuromodulatory, anti-oxidant, and anti-inflammatory activities, thus suggesting a neuroprotective effect. These findings help to explain the beneficial use of these HE extracts of P.daemia in traditional medicine to treat epilepsy in Cameroon.

PTZ kindling model for epileptogenesis, refractory epilepsy, and associated comorbidities: relevance and reliability

Pentylenetetrazole (PTZ)-induced seizure is one of the gold standard mouse models for rapid evaluation of novel anticonvulsants. Synchronically, PTZ induced kindling in mice is also a simple and well accepted model of chronic epilepsy. PTZ kindling has been explored for studying epileptogenesis, epilepsy-associated comorbidities, and refractory epilepsy. This review summarizes the potential of PTZ kindling in mice and its modifications for its face, construct, and predictive validity to screen antiepileptogenic drugs, combined or add on novel and safe therapies for treatment of epilepsy-associated depression and cognitive impairment as well as effective interventions for pharmacoresistant epilepsy.

Anti-Seizure Activity of 1-Adamantane Carboxylic Acid in Common Experimental Seizure Models: Role of Benzodiazepine-GABAA Receptors

BAckground

Despite introduction of modern antiepileptic drugs, 30% of epileptic patients are still drug resistant. Remarkable three-dimensional spatial structure of 1-Adamantane carboxylic acid (AdCA), yet the simplicity of the molecule, makes AdCA a promising lead compound.

Methods

Sedative/motor impairment and 24-h mortality rate of AdCA were determined in mice. Impact of AdCA on (1) threshold and occurrence of clonic seizures induced by pentylenetetrazole (PTZ) in mice, (2) incidence of tonic seizures induced by maximal electroshock (MES) in mice, and (3) incidence of generalized seizures and duration of evoked afterdischarges in amygdala-kindled rats, were determined. The role of benzodiazepine receptors in the AdCA effect on clonic seizure threshold was also assessed.

Results

AdCA showed sedative effect (median toxic dose [TD50] = 224.5 [190.2-289.9] mg/kg). Median lethal dose (LD50) = 805.5 (715.2–988.1) mg/kg was obtained for AdCA. The compound increased PTZ seizure threshold from 180 mg/kg (p < 0.05) and also inhibited the incidence of clonic seizures (ED50 = 256.3 [107.4-417.3] mg/kg). AdCA also decreased afterdischarge duration (p < 0.01) and the incidence of generalized seizures (ED50 < 50 mg/kg) in the kindled rats. However, AdCA did not protect mice against tonic seizures induced by MES. The benzodiazepine receptor antagonist flumazenil prevented the increase of seizure threshold by AdCA.

Conclusion

AdCA possesses anticonvulsant activity in kindling and PTZ models through the activation of benzodiazepine/GABAA receptors with acceptable therapeutic index.

Cognition and memory impairment attenuation via reduction of oxidative stress in acute and chronic mice models of epilepsy using antiepileptogenic Nux vomica

Ethnopharmacological relevance Processed Nux vomica seed extracts and homeopathic medicinal preparations (HMPs) are widely used in traditional Indian and Chinese medicine for respiratory, digestive, neurological and behavioral disorders. Antioxidant property of Nux vomica is well known and recent investigation has highlighted the anticonvulsant potential of its homeopathic formulation.

AIM OF THE STUDY

To explore the anticonvulsant and antiepileptogenic potential of Nux vomica HMPs (6CH, 12CH and 30CH potency) in pentylenetetrazole (PTZ) induced acute and chronic experimental seizure models in mice and investigate their effects on cognition, memory, motor activity and oxidative stress markers in kindled animals.

MATERIALS AND METHODS

Acute seizures were induced in the animals through 70 mg/kg (i.p.) administration of PTZ followed by the evaluation of latency and duration of Generalized tonic-clonic seizures (GTCS). Subconvulsive PTZ doses (35 mg/kg, i.p.) induced kindling in 29 days, which was followed by assessment of cognition, memory and motor impairment through validated behavioral techniques. The status of oxidative stress was estimated through measurement of MDA, GSH and SOD.

RESULTS

HMPs delayed the latency and reduced the duration of GTCS in acute model signifying possible regulation of GABAergic neurotransmission. Kindling was significantly hindered by the HMPs that justified the ameliorated cognition, memory and motor activity impairment. The HMPs attenuated lipid peroxidation by reducing MDA level and strengthened the antioxidant mechanism by enhancing the GSH and SOD levels in the kindled animals.

CONCLUSIONS

Nux vomica HMPs showed anticonvulsant and antiepileptogenic potency in acute and chronic models of epilepsy. The test drugs attenuated behavioral impairment and reduced the oxidative stress against PTZ induced kindling owing to which they can be further explored for their cellular and molecular mechanism(s).

Dysregulation of REV-ERBα impairs GABAergic function and promotes epileptic seizures in preclinical models

To design potentially more effective therapies, we need to further understand the mechanisms underlying epilepsy. Here, we uncover the role of Rev-erbα in circadian regulation of epileptic seizures. We first show up-regulation of REV-ERBα/Rev-erbα in brain tissues from patients with epilepsy and a mouse model. Ablation or pharmacological modulation of Rev-erbα in mice decreases the susceptibility to acute and chronic seizures, and abolishes diurnal rhythmicity in seizure severity, whereas activation of Rev-erbα increases the animal susceptibility. Rev-erbα ablation or antagonism also leads to prolonged spontaneous inhibitory postsynaptic currents and elevated frequency in the mouse hippocampus, indicating enhanced GABAergic signaling. We also identify the transporters Slc6a1 and Slc6a11 as regulators of Rev-erbα-mediated clearance of GABA. Mechanistically, Rev-erbα promotes the expressions of Slc6a1 and Slc6a11 through transcriptional repression of E4bp4. Our findings propose Rev-erbα as a regulator of synaptic function at the crosstalk between pathways regulating the circadian clock and epilepsy.

Suppression of BACE1 and amyloidogenic/RAGE axis by sitagliptin ameliorates PTZ kindling-induced cognitive deficits in rats

The debilitating nature of cognitive impairment in epilepsy and the potential of some traditional antiepileptics to further deteriorate cognitive function are areas of growing concern. Glucagon-like peptide-1 (GLP-1) deficiency has been linked to reduced seizure threshold as well as cognitive dysfunction. Here, we tested whether sitagliptin (SITA), by virtue of its neuroprotective properties, could alleviate both epilepsy and associated cognitive dysfunction in a rat model of kindling epilepsy. Chemical kindling was induced by subconvulsive doses of pentylenetetrazol (PTZ) (30 mg/kg; i.p). SITA (50 mg/kg; p.o) was administered 1 h before PTZ injections. SITA conceivably attenuated PTZ hippocampal histological insult, preserved neuronal integrity and amended neurotransmitter perturbations in rat hippocampi paralleled with enhanced hippocampal GLP-1 levels as well as the downstream cAMP content and protein kinase A (PKA) activity. Moreover, SITA improved cognitive functioning of rats in the Morris water maze which was coupled with hampered hippocampal p(Ser⁴⁰⁴)-tau and β-amyloid proteins. SITA replenished p(Ser⁹)-glycogen synthase kinase-3β (GSK-3β). It also opposed the boosted matrix metalloproteinase-9 (MMP-9), brain-derived neurotrophic factor (BDNF), and insulin-like growth factor-1 (IGF-1) levels associated with PTZ administration along with mitigation of both β-secretase-1 (BACE1) immunoreactivity and receptor for advanced glycation end products (RAGE) protein level in rat hippocampi. In conclusion, SITA subdues epileptic and cognitive upshots of PTZ kindling in rats, which might correspond to the modulation of BACE1, amyloidogenic/RAGE axis as well as GSK-3β/MMP-9/BDNF signaling cascade. SITA effects are probably mediated via boosting GLP-1 and subsequently enhancing GLP-1/GLP-1R signaling.

Effects of Diclofenac Versus Meloxicam in Pentylenetetrazol-Kindled Mice

Epilepsy comes after stroke as the most common chronic neurological disorder worldwide. Inflammation enhances neuronal hyperexcitability that could provide a background setting for the development of epilepsy. The aim of this study was to assess the effect of valproate (VAL), diclofenac (DIC), meloxicam (MEL), VAL + MEL and VAL + DIC in pentylenetetrazol (PTZ) kindled mice. Seventy mice were randomly allocated into 7 equal groups; Control, PTZ, VAL, DIC, MEL, VAL + MEL and VAL + DIC groups. Kindling was induced by PTZ (40 mg/kg, i.p.) injection every other day for 17 days. The drugs were administered, 30 min before each PTZ injection till the end of the schedule. Seizure score, latency, duration and mortality rate were recorded in all groups. Tumor necrosis factor- α (TNF-α), interleukin-1β (IL-1β), malondialdehyde (MDA) and prostaglandin E2 (PGE2) levels as well as reduced glutathione (GSH) content were assessed in brain homogenate at the end of the schedule. VAL, DIC, MEL, VAL + MEL and VAL + DIC decreased seizure score and duration. Meanwhile, they increased the latency period. PTZ increased TNF-α, IL-1β, MDA, and PGE2 levels meanwhile, it decreased GSH content. Administration of VAL, DIC, MEL, VAL + MEL and VAL + DIC decreased TNF-α, IL-1β, MDA, and PGE2 levels meanwhile, they increased GSH content in the brain homogenates. Effects of VAL + DIC combination on the studied parameters were significant in relation to VAL. VAL, DIC, MEL, VAL + MEL and VAL + DIC produced anticonvulsant effect and mitigated inflammation and oxidative stress in PTZ-kindled mice. Interestingly, DIC rather than MEL enhanced the anticonvulsant effect VAL.

The current approach of the Epilepsy Therapy Screening Program contract site for identifying improved therapies for the treatment of pharmacoresistant seizures in epilepsy

The Epilepsy Therapy Screening Program (ETSP), formerly known as the Anticonvulsant Screening Program (ASP), has played an important role in the preclinical evaluation of many of the antiseizure drugs (ASDs) that have been approved by the FDA and thus made available for the treatment of seizures. Recent changes to the animal models used at the contract site of the ETSP at the University of Utah have been implemented in an attempt to better model the unmet clinical needs of people with pharmacoresistant epilepsy and thus identify improved therapies. In this review, we describe the changes that have occurred over the last several years in the screening approach used at the contract site and, in particular, detail the pharmacology associated with several of the animal models and assays that are either new to the program or have been recently characterized in more depth. There is optimism that the refined approach used by the ETSP contract site, wherein etiologically relevant models that include those with spontaneous seizures are used, will identify novel, potentially disease modifying therapies for people with pharmacoresistant epilepsy and those at risk for developing epilepsy. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.

Antagonism of Histamine H3 receptors Alleviates Pentylenetetrazole-Induced Kindling and Associated Memory Deficits by Mitigating Oxidative Stress, Central Neurotransmitters, and c-Fos Protein Expression in Rats

Histamine H3 receptors (H3Rs) are involved in several neuropsychiatric diseases including epilepsy. Therefore, the effects of H3R antagonist E177 (5 and 10 mg/kg, intraperitoneal (i.p.)) were evaluated on the course of kindling development, kindling-induced memory deficit, oxidative stress levels (glutathione (GSH), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD)), various brain neurotransmitters (histamine (HA), acetylcholine (ACh), γ-aminobutyric acid (GABA)), and glutamate (GLU), acetylcholine esterase (AChE) activity, and c-Fos protein expression in pentylenetetrazole (PTZ, 40 mg/kg) kindled rats. E177 (5 and 10 mg/kg, i.p.) significantly decreased seizure score, increased step-through latency (STL) time in inhibitory avoidance paradigm, and decreased transfer latency time (TLT) in elevated plus maze (all P < 0.05). Moreover, E177 mitigated oxidative stress by significantly increasing GSH, CAT, and SOD, and decreasing the abnormal level of MDA (all P < 0.05). Furthermore, E177 attenuated elevated levels of hippocampal AChE, GLU, and c-Fos protein expression, whereas the decreased hippocampal levels of HA and ACh were modulated in PTZ-kindled animals (all P < 0.05). The findings suggest the potential of H3R antagonist E177 as adjuvant to antiepileptic drugs with an added advantage of preventing cognitive impairment, highlighting the H3Rs as a potential target for the therapeutic management of epilepsy with accompanied memory deficits.

Probiotics and Nigella sativa extract supplementation improved behavioral and electrophysiological effects of PTZ-induced chemical kindling in rats

INTRODUCTION

Epilepsy is a most common neurological disorder that has negative effects on cognition. In the present study, we investigated the protective effect of Nigella sativa (NS) and probiotics on seizure activity, cognitive performance, and synaptic plasticity in pentylenetetrazole (PTZ) kindling model of epilepsy.

METHODS

One hundred and forty-four rats were divided into 2 experiments: In experiment 1, animals were grouped and treated as follows: 1) control (PTZ + saline), 2) NS treatment, 3) probiotic treatment, and 4) NS and probiotic treatment. Six weeks after the treatment, PTZ kindling were performed, and 48 h after kindling, spatial learning and memory were measured in Morris water maze (MWM) test. Animals in experiment 2 received the same treatment as experiment 1: in control nonkindled groups, control animals were treated with probiotics, NS, and probiotics + NS. Six weeks after the treatment, PTZ kindling were performed, and 48 h after kindling, field potentials were recorded from the dentate gyrus area of the hippocampus; synaptic transmission and long-term potentiation (LTP) was measured.

RESULTS

The results showed that the probiotic and NS supplementation significantly reduces kindling development so that animals in PTZ + NS + probiotic did not show full kindling. In MWM test, the escape latency and traveled path in the kindled group were significantly higher than the control group. In PTZ + NS + probiotics, these parameters were significantly lower than those in the PTZ + saline group. Adding probiotic and NS supplementation significantly reduced population spike (PS)-LTP as compared with the PTZ + saline group.

CONCLUSION

Probiotic and NS supplementation have some protection against seizure, seizure-induced cognitive impairment, and hippocampal LTP in kindled rats.

An interaction study of Ocimum sanctum L. and levetiracetam in pentylenetetrazole kindling model of epilepsy

ETHNOPHARMACOLOGICAL RELEVANCE

Ocimum sanctum L. commonly known as tulsi (synonym of Ocimum tenuiflorum L.) is widely used in Ayurveda medicine and is having multitude neuromodulatory effect including the anticonvulsant effect in acute seizure models as per previous studies. In India, it is used for the treatment of epilepsy as traditional medicine. However, its role in chronic seizure model and interaction with newer antiepileptic drugs has not been investigated, which will enhance its translational value.

AIM OF THE STUDY

Current study investigated the effect of Ocimum on chronic seizure model and its interaction with levetiracetam (LEV), a newer antiepileptic drug.

MATERIALS AND METHODS

The adjuvant role of Ocimum sanctum hydroalcoholic extracts (OSHE) 1000 mg/kg along with LEV 300 mg/kg was studied in adult male Wistar rats with mean weight of 227.84 ± 21.68 g using pentylenetetrazole (30 mg/kg, i.p.) kindling (K) (with maximum 24 injections on alternate days and challenge on 7th-day). Along with seizure score, neurobehavioral, brain tissue oxidative stress and histopathology status were assessed. Pharmacokinetic interaction was assessed between LEV and OSHE after 14 days of drug treatment.

RESULTS

K-LEV + OSHE had least seizure score during kindling and on the pentylenetetrazole-challenge test (p=0.031) than other kindling groups. Seizure protection was more in K-LEV + OSHE (85.72%) than others (K-LEV-42.86%, K-OSHE-42.86%, and K-Control-28.58%). Ocimum treated groups had better memory retention potential as evident from Morris water maze (MWM), passive avoidance test but not in an elevated plus maze test. Oxidative-stress was lower in Ocimum treated groups than K-Control group. As per histopathology, K-LEV + OSHE group had the least neuronal degeneration among kindling groups. There was no significant pharmacokinetic interaction between LEV and OSHE, except increased T_max in LEV + OSHE group than LEV alone (p=0.009).

CONCLUSIONS

Ocimum per se and combination with levetiracetam treatment exerted better seizure control, memory retention, oxidative stress reduction, and neuronal structure preservation than kindling control group. There was a very minimal drug interaction between Ocimum and LEV. So, Ocimum as an adjuvant to LEV may be shelpful in enhancing the antiepileptic effect and also in minimizing the adverse effects.

Inhibition of USP15 Prevent Glutamate-Induced Oxidative Damage by Activating Nrf2/HO-1 Signaling Pathway in HT22 Cells

Oxidative stress has been identified as the significant mediator in epilepsy, which is a chronic disorder in central nervous system. About 30% of epilepsy patients are refractory to antiepileptic drug treatment. However, the underlying mechanism of oxidative damage in epilepsy needs further investigation. In our study, we first find that ubiquitin-specific peptidase 15 (USP15) expression was upregulated in a pentylenetetrazole (PTZ) kindled rat model of epilepsy. Silencing USP15 protected against glutamate-mediated neuronal cell death, and inhibited the high expression levels of cleaved caspase-3. Knockout of USP15 significantly reduced intracellular reactive oxygen species (ROS) levels and enhanced superoxide dismutase (SOD) activity in HT22 cells under the exposure to glutamate treatment. Furthermore, USP15 inhibition induced nuclear factor erythroid-derived 2-related factor2 (Nrf2) nuclear translocation and promoted protein expression level of heme oxygenase (HO-1). Taken together, our findings first reveal a role of USP15 in the pathogenesis of epilepsy, and silencing USP15 in vitro protects against glutamate-mediated cytotoxicity in HT22 cells. Pharmacological inhibition of USP15 may alleviate epileptic seizures via fighting against oxidative damage, providing a novel antiepileptic target.

Diazepam and electrical stimulation of paleocerebellar cortex inhibits seizures in pentylenetetrazol‑kindled rats

The cerebellum is a potent anti‑epileptic target for deep brain stimulation in patients with drug‑resistant epilepsy. The effects of such stimulation, however, may also favor seizure activity. Our goal was to investigate the effect of cerebellar electrical stimulation (ES) alone and in combination with the anti‑epileptic drug diazepam (DIA) on seizure outcome. We used a rat model of pentylenetetrazol kindling, which is characterized by seizures followed by deteriorations in central benzodiazepine‑GABAA (BDZ‑GABAA) receptors. We tested the effects of ES alone and in combination with DIA (0.1 and 1.0 mg/kg) on seizures. Our data demonstrated: 20 ES trials can prevent the recurrence of clonic‑tonic kindled seizures, administration of either DIA‑0.1 or ES (5 trials) alone is ineffective on seizures, and combining DIA‑0.1 and 5 ES or DIA‑1.0 and 5 ES caused an additive effect, prolonged the latency to seizure onset, and prevented recurrence of clonic‑tonic seizures. We also observed that ES alone produced either facilitation or inhibition of seizures on EEG. In contrast, the same ES inhibited EEG seizures when delivered after a combination of DIA‑1.0 and 5 ES and ultimately prevented the facilitation of the discharges. Lastly, we demonstrated that seizure suppression is intensified when cortical ES is performed after DIA administration. Our data supported the hypothesis that both BDZ‑GABAA receptor activity along with cerebellar output comprise the potential mechanisms underlying the peculiar effects of deep brain stimulation in the cerebellum on seizures.

Mild foot electrical stimulation is comparable with phenytoin in inhibiting pentylenetetrazol-induced kindling in rats

Increasing evidence demonstrates that electric stimulation has anticonvulsant effects. The present study was undertaken to investigate the effects of mild foot electrical stimulation (MFES) on the development of pentylenetetrazol (PTZ) kindling and compare its effectiveness with the more commonly used treatment, phenytoin. Kindling was induced in rats by repeated injections (every 24 h) of PTZ (37.5 mg/kg). The rats were subjected to either MFES (0.2 mA in intensity for a 160 ms duration with a 160 ms interval for 20 min) or phenytoin (30 mg/kg) before PTZ injections. Following this treatment, rats received MFES every other day for 10 days or 26 days after establishment of PTZ kindling. The data showed that MFES significantly inhibited development of chemical kindling induced by PTZ in rats (p = 0.001, as compared to PTZ-treated animals). This inhibitory effect is comparable with the effect of 30 mg/kg doses of phenytoin (P = 0.99, as compared to phenytoin group). However, 10 days or 26 days durations of MFES had no effect on established kindled seizures (P = 0.58 as compared to PTZ-treated animals). Our data demonstrate that although MFES significantly inhibited the development of chemical kindling, this experimental paradigm had no effect on established kindled seizures.

Interaction of sigma-1 receptor modulators with seizure development in pentylenetetrazole-induced kindled mice

This study aimed to investigate the effects of sigma receptor modulators, opipramol and BD-1063, on epileptogenesis in pentylenetetrazole (PTZ)-kindling model of epilepsy. Mice (n = 6/group) were received PTZ (30 mg/kg), PTZ plus opipramol (5 or 10 mg/kg), PTZ plus opipramol (5 mg/kg) plus BD-1063 (5 mg/kg, a selective sigma-1 receptor antagonist), and PTZ plus BD-1063 on alternate days for 15 days. Opipramol (5 and 10 mg/kg) + PTZ groups became fully kindled and had higher seizure scores compared to the PTZ group. In contrast, the PTZ plus BD-1063 and the PTZ plus opipramol (5 mg/kg) plus BD-1063 group did not show full kindling. These findings indicate that opipramol has a pro-convulsant effect, which is possibly mediated through activation of sigma-1 receptors.

The role of UCH-L1, MMP-9, and GFAP as peripheral markers of different susceptibility to seizure development in a preclinical model of epilepsy

In our study, we assessed the potency of the brain-derived proteins ubiquitin carboxy-terminal hydrolase L1 (UCH-L1), matrix metalloproteinase 9 (MMP-9), glial fibrillary acidic protein (GFAP) and the immune activation indicators interleukin 1β (IL-1β) and interleukin 6 (IL-6) as peripheral biomarkers of different susceptibilities to kindling in a preclinical model. We observed increased plasma UCH-L1 levels in kindled vs. control animals. Furthermore, MMP-9 and IL-1β concentrations were the lowest in rats resistant to kindling. In summary, UCH-L1 is an indicator of neuronal loss and BBB disruption after seizure. MMP-9 and IL-1β may indicate resistance to kindling. UCH-L1, MMP-9 and IL-1β may have utility as peripheral biomarkers with translational potency in the clinic.

Evaluation of anticonvulsant and antiepileptogenic activity of Euphorbia nivulia in PTZ-induced kindling model of epilepsy in mice

Epilepsy remains a major chronic neurological disorder with significantly higher refractory seizure rate. Based on the folk medicine literature, we explored the anticonvulsant and antiepileptogenic activity of aqueous ethanolic extracts of Fumaria indica, Euphorbia lactea, Euphorbia helioscopia, Neurada procumbens, and Euphorbia nivulia. The acute anticonvulsant activity of the extracts was determined at different concentrations in different groups of Swiss albino mice. Among all the materials tested, the ethanolic extracts of Euphorbia nivulia (eth-EN) alone was found to exhibit concentration-dependent anticonvulsant effects when evaluated against the acute convulsant dose of Pentylenetetrazole (PTZ, 90mg/kg, s.c.). eth-EN extract at 100mg/kg i.p concentration showed maximum protection against the PTZ induced mortality (P<0.05). eth-EN (100mg/kg) treated animals also showed significant reduction in the progression of epileptogenesis (P<0.05) when tested against the PTZ-induced (50mg/kg s.c.) chemical kindling model of epilepsy. The FT-IR spectra of this extract showed both known and unknown spectral peaks from which the presence of the functional groups; i.e. aromatics, diketones, alkenes, carbonyls, carboxylic acids and amide compounds were confirmed. The unknown peaks strongly suggested the presence of novel compounds that may be responsible for its anticonvulsant and antiepileptogenic activity.

Astrocytic mobilization of glutathione peroxidase-1 contributes to the protective potential against cocaine kindling behaviors in mice via activation of JAK2/STAT3 signaling

Compelling evidence indicates that oxidative stress contributes to cocaine neurotoxicity. The present study was performed to elucidate the role of the glutathione peroxidase-1 (GPx-1) in cocaine-induced kindling (convulsive) behaviors in mice. Cocaine-induced convulsive behaviors significantly increased GPx-1, p-IkB, and p-JAK2/STAT3 expression, and oxidative burdens in the hippocampus of mice. There was no significant difference in cocaine-induced p-IkB expression between non-transgenic (non-TG) and GPx-1 overexpressing transgenic (GPx-1 TG) mice, but significant differences were observed in cocaine-induced p-JAK2/STAT3 expression and oxidative stress between non-TG and GPx-1 TG mice. Cocaine-induced glial fibrillary acidic protein (GFAP)-labeled astrocytic level was significantly higher in the hippocampus of GPx-1 TG mice. Triple-labeling immunocytochemistry indicated that GPx-1-, p-STAT3-, and GFAP-immunoreactivities were co-localized in the same cells. AG490, a JAK2/STAT3 inhibitor, but not pyrrolidone dithiocarbamate, an NFκB inhibitor, significantly counteracted GPx-1-mediated protective potentials (i.e., anticonvulsant-, antioxidant-, antiapoptotic-effects). Genetic overexpression of GPx-1 significantly attenuated proliferation of Iba-1-labeled microglia induced by cocaine in mice. However, AG490 or astrocytic inhibition (by GFAP antisense oligonucleotide and α-aminoadipate) significantly increased Iba-1-labeled microglial activity and M1 phenotype microglial mRNA levels, reflecting that proinflammatory potentials were mediated by AG490 or astrocytic inhibition. This microglial activation was less pronounced in GPx-1 TG than in non-TG mice. Furthermore, either AG490 or astrocytic inhibition significantly counteracted GPx-1-mediated protective potentials. Therefore, our results suggest that astrocytic modulation between GPx-1 and JAK2/STAT3 might be one of the underlying mechanisms for protecting against convulsive neurotoxicity induced by cocaine.

Cannabidiol reduces seizures and associated behavioral comorbidities in a range of animal seizure and epilepsy models

OBJECTIVE

Epilepsy is a progressive neurological disease characterized by recurrent seizures and behavioral comorbidities. We investigated the antiseizure effect of cannabidiol (CBD) in a battery of acute seizure models. Additionally, we defined the disease-modifying potential of chronic oral administration of CBD on associated comorbidities in the reduced intensity status epilepticus-spontaneous recurrent seizures (RISE-SRS) model of temporal lobe epilepsy (TLE).

METHODS

We evaluated the acute antiseizure effect of CBD in the maximal electroshock seizure, 6-Hz psychomotor seizure, and pentylenetetrazol acute seizure tests, as well as the corneal kindling model of chronic seizures in mice following intraperitoneal administration. Median effective or behavioral toxic dose was determined in both mice and rats. Next, we tested an intravenous preparation of CBD (10 mg/kg single dose) in a rat model of pilocarpine-induced status epilepticus. We defined the effect of chronic CBD administration (200 mg/kg orally) on spontaneous seizures, motor control, gait, and memory function in the rat RISE-SRS model of TLE.

RESULTS

CBD was effective in a battery of acute seizure models in both mice and rats following intraperitoneal administration. In the pilocarpine-induced status epilepticus rat model, CBD attenuated maximum seizure severity following intravenous administration, further demonstrating CBD's acute antiseizure efficacy in this rat model. We established that oral CBD attenuated the time-dependent increase in seizure burden and improved TLE-associated motor comorbidities of epileptic rats in the RISE-SRS model without affecting gait. Chronic administration of CBD after the onset of SRS ameliorated reference memory and working memory errors of epileptic animals in a spatial learning and memory task.

SIGNIFICANCE

The present study illustrates that CBD is a well-tolerated and effective antiseizure agent and illustrates a potential disease-modifying effect of CBD on reducing both seizure burden and associated comorbidities well after the onset of symptomatic seizures in a model of TLE.

Effects of Leontice leontopetalum and Bongardia chrysogonum on oxidative stress and neuroprotection in PTZ kindling epilepsy in rats

We investigated the effects of Leontice leontopetalum and Bongardia chrysogonum on apoptosis, gamma-aminobutyric acid (GABAA) receptor positive cell number, cyclin-B1 and bcl-2 levels and oxidative stress in pentylenetetrazol (PTZ) kindling in rats. Kindling was produced by subconvulsant doses of PTZ treatments in rats. Wistar albino rats were divided into 4 groups; Control, PTZ treated (PTZ), PTZ+L. leontopetalum extract treated (PTZ+LLE) and PTZ+B. chrysogonum extract treated (PTZ+BCE) groups. Extracts were given a dose (200 mg/kg) 2h before each PTZ injection. PTZ treatment significantly decreased the glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) activities and bcl-2 levels and increased the total oxidant status (TOS), malondialdehyde (MDA), cyclin B1, oxidative stress index (OSI) and number of neurons that expressed GABAA receptors when compared to the control. LLE and BCE possessed antioxidant activity in the brain and ameliorated PTZ induced oxidative stress, decreased cyclin-B1, increased bcl-2 levels, and kept the GABAA receptor number similar to that of the control despite the PTZ application.

Naringin in a combined therapy with phenytoin on pentylenetetrazole-induced kindling in rats

Phenytoin (Dilantin) is an orally active, use-dependent voltage-gated sodium channel inhibitor and is a potent, economical, and widely used anticonvulsant agent. The objective of the present study was to investigate the effect of the combined treatment of naringin (40 mg/kg and 80 mg/kg) and phenytoin on prevention of seizure attacks, development of kindling, oxidative stress, cognitive impairment, and neurochemicals in the frontal cortex, temporal cortex, and hippocampus, and morphological changes in the hippocampus. Treatment with the high dose of naringin (80 mg/kg) along with phenytoin has shown to offer protection against seizures, development of kindling, and cognition enhancement through Y-maze test and improved % conditioned avoidance response (% CAR) through pole climbing test in pentylenetetrazole (PTZ)-induced kindling model. It has also been shown to improve neurochemical balance by elevating levels of Gamma amino butyric acid (GABA) and dopamine, decreasing levels of glutamate, oxidative biomarker (malondialdehyde (MDA)), and increasing levels of antioxidants (glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), and total thiol and offered neuroprotection in the hippocampus. So, coadministration of naringin with phenytoin offers a potential treatment option for drug-resistant epilepsy and associated comorbidities. Interpretable research on flavonoids will support the clinical evidence for the recommendation of flavonoids as supplements with antiepileptic drugs (AEDs) for curtailing pharmacoresistant epilepsy and AED-associated comorbidities.

The anti-seizure effects of IV 5α-dihydroprogesterone on amygdala-kindled seizures in rats

OBJECTIVE

The present study investigated the anti-seizure effects of 5α-dihydroprogesterone (DHP) in an animal model of human drug-resistant focal seizures with impaired awareness. DHP was administered via the intravenous (IV) route.

METHODS

Female Wistar rats were implanted with an electrode in the right basolateral amygdala. They were then kindled to 15 stage 5 seizures, stability tested, and cannulated in the jugular vein. Multiple doses of IV DHP were tested against focal electrographic seizures and secondarily generalized convulsions. The time-course of DHP's action was also examined.

RESULTS

The dose-response study, done at 5 min after injection, showed a dose-dependent suppression of both generalized and focal seizures, with an ED50 of 1.69 mg/kg for the generalized convulsive seizures and an ED50 of 3.48 mg/kg for the focal electrographic seizures. Ataxia, as rated by the Löscher ataxia scale, was also seen, with a TD50 of 3.57 mg/kg. The time-response study, done at the ED75 for focal seizure suppression, showed suppression of both generalized and focal seizures from immediately after injection to about 60 min post-injection.

SIGNIFICANCE

DHP has demonstrated anti-seizure effects in a drug-resistant model of human focal seizures with impaired awareness. Its analogs might be developed as new anti-seizure drugs.

Role of β2/3-specific GABA-A receptor isoforms in the development of hippocampus kindling epileptogenesis

OBJECTIVE

Subunit-specific positive allosteric modulators (PAMs) of gamma-aminobutyric acid-A (GABA-A) receptors are commonly used to uncover the role of GABA-A receptor isoforms in brain function. Recently, we have designed novel PAMs selective for β_2/3-subunit containing GABA-A receptors (β_2/3-selective PAMs) that are nonbenzodiazepine site-mediated and do not show an α-subunit isoform selectivity, yet exhibit anxiolytic efficacy with reduced potential for sedation, cognitive impairment, and tolerance. In this study, we used three novel β_2/3-selective PAMs (2-261, 2-262, and 10029) with differential β_2/3-subunit potency to identify the role of β_2/3-selective receptor isoforms in limbic epileptogenesis.

METHODS

Experimental epileptogenesis was induced in mice by daily hippocampus stimulations until each mouse showed generalized (stage 5) seizures. Patch-clamp electrophysiology was used to record GABA-gated currents. Brain levels of β_2/3-selective PAMs were determined for mechanistic correlations.

RESULTS

Treatment with the β_2/3-selective PAMs 2-261 (30mg/kg), 2-262 (10mg/kg), and 10029 (30mg/kg), 30min prior to stimulations, significantly suppressed the rate of development of kindled seizure activity without affecting the afterdischarge (AD) signal, indicating their disease-modifying activity. The β_2/3-selective agents suppressed chemical epileptogenesis in the pentylenetetrazol model. Test doses of these agents were devoid of acute antiseizure activity in the kindling model.

CONCLUSION

These findings demonstrate that β_2/3-selective PAMs can moderately retard experimental epileptogenesis, indicating the protective role of β_2/3-subunit GABA-A receptor isoforms in the development of epilepsy.

Overexpression of zinc-α2-glycoprotein suppressed seizures and seizure-related neuroflammation in pentylenetetrazol-kindled rats

BACKGROUND

Zinc-α2-glycoprotein (ZAG) is a 42-kDa protein reported as an anti-inflammatory adipocytokine. Evidences from clinical and experimental studies revealed that brain inflammation plays important roles in epileptogenesis and seizure. Interestingly, closely relationship between ZAG and many important inflammatory mediators has been proven. Our previous study identified ZAG in neurons and found that ZAG is decreased in epilepsy and interacts with TGFβ and ERK. This study aimed to investigate the role of ZAG in seizure and explore its effect on seizure-related neuroinflammation.

METHODS

We overexpressed AZGP1 in the hippocampus of rats via adeno-associated virus vector injection and observed their seizure behavior and EEG after pentylenetetrazol (PTZ) kindling. The level of typical inflammation mediators including TNFα, IL-6, TGFβ, ERK, and ERK phosphorylation were determined.

RESULTS

The overexpression of AZGP1 reduced the seizure severity, prolonged the latency of kindling, and alleviated epileptiform discharges in EEG changes induced by PTZ. Overexpression of AZGP1 also suppressed the expression of TNFα, IL-6, TGFβ, and ERK phosphorylaton in PTZ-kindled rats.

CONCLUSIONS

ZAG may inhibit TGFβ-mediated ERK phosphorylation and inhibit neuroinflammation mediated by TNFα and IL-6, suggesting ZAG may suppress seizure via inhibiting neuroinflammation. ZAG may be a potential and novel therapeutic target for epilepsy.

Assessment of luteolin isolated from Eclipta alba leaves in animal models of epilepsy

CONTEXT

Eclipta alba (Linn) Hassk. (Asteraceae) has been reported to be a nerve tonic and has been used to treat epilepsy in folk medicine.

OBJECTIVE

The present study isolates and characterizes luteolin from E. alba and evaluates its antiepileptic potential in chemically induced acute and chronic models in mice.

MATERIALS AND METHODS

The methanol extract (16.85% w/w) of E. alba leaves was subjected to fractionation for isolation of luteolin. In acute pentylenetetrazole (PTZ) model, luteolin (5, 10, 20 mg/kg, i.p.) was administered 30 min prior to PTZ injection (100 mg/kg) in Swiss albino mice. Kindling was induced by chronic administration of PTZ (35 mg/kg) on every alternate day (48 days). Luteolin was investigated on the course of kindling development and oxidative stress markers [reduced glutathione (GSH) and malondialdehyde (MDA)] in kindled mice.

RESULTS

Single-dose pretreatment with luteolin (10 and 20 mg/kg, i.p.) was found to be effective in an acute PTZ model (100% protection from mortality) and it did not exhibit any effect on motor coordination at the same doses. PTZ-induced kindling was significantly (p < 0.001) prevented by luteolin (5, 10, 20 mg/kg, i.p.) in a dose-dependent manner. Luteolin restored levels of reduced GSH (p < 0.001) and decreased the level of MDA (p < 0.001), a marker of lipid peroxidation.

DISCUSSION AND CONCLUSION

The results of the present study demonstrated that luteolin had an anticonvulsant effect in an acute PTZ model. Luteolin exhibited and inhibitory effect on the course of kindling and associated oxidative stress and hence could be a potential molecule in the treatment of epilepsy.

Regulation of kindling epileptogenesis by hippocampal Toll-like receptors 2

This study examined whether Toll-like receptors 2 (TLR2) contribute to rapid kindling epileptogenesis. A TLR2 agonist, lipoteichoic acid (LTA), LTA antibody (LTA-A), or normal saline (control) was administered daily over 3 consecutive days, unilaterally into ventral hippocampus of adult male Wistar rats. Thirty minutes after the last injection, the animals were subjected to a rapid kindling procedure. The ictogenesis was gauged by comparing afterdischarge threshold (ADT) and afterdischarge duration (ADD) before the treatments, after the treatments prior to kindling, and 24 h after kindling. Kindling progression and retention were analyzed using video recording. The results showed that before kindling, LTA produced an ADT reduction. Neither LTA nor LTA-A affected baseline ADD. On kindling progression, LTA accelerated occurrence of generalized seizures, whereas LTA-A delayed this effect. Treatment with LTA-A reduced the number of secondary generalized complex partial seizures. Twenty-four hours after kindling, the rats of both the saline and LTA groups showed increased hippocampal excitability as compared with prekindling parameters. Administration of LTA-A prevented kindling-induced increase of hippocampal excitability. Immunostaining revealed that LTA-A attenuated the inflammatory response produced by seizures. These findings suggest that the activation of TLR2 in the hippocampus may facilitate limbic epileptogenesis.

Comparative studies on the effects of clinically used anticonvulsants on the oxidative stress biomarkers in pentylenetetrazole-induced kindling model of epileptogenesis in mice

BACKGROUND

Oxidative stress plays a key role in the pathogenesis of epilepsy and contributes in underlying epileptogenesis process. Anticonvulsant drugs targeting the oxidative stress domain of epileptogenesis may provide better control of seizure. The present study was carried out to investigate the effect of clinically used anti-epileptic drugs (AEDs) on the course of pentylenetetrazole (PTZ)-induced kindling and oxidative stress markers in mice.

METHODS

Six mechanistically heterogeneous anticonvulsants: phenobarbital, phenytoin, levetiracetam, pregabalin, topiramate, and felbamate were selected and their redox profiles were determined. Diazepam was used as a drug control for comparison. Kindling was induced by repeated injections of a sub-convulsive dose of PTZ (50 mg/kg, s.c.) on alternate days until seizure score 5 was evoked in the control kindled group. Anticonvulsants were administered daily. Following PTZ kindling, oxidative stress biomarkers were assessed in homogenized whole brain samples and estimated for the levels of nitric oxide, peroxide, malondialdehyde, protein carbonyl, reduced glutathione, and activities of nitric oxide synthase and superoxide dismutase.

RESULTS

Biochemical analysis revealed a significant increase in the levels of reactive oxygen species with a parallel decrease in endogenous anti-oxidants in PTZ-kindled control animals. Daily treatment with levetiracetam and felbamate significantly decreased the PTZ-induced seizure score as well as the levels of nitric oxide (p<0.001), nitric oxide synthase activity (p<0.05), peroxide levels (p<0.05), and malondialdehyde (p<0.05). Levetiracetam and felbamate significantly decreased lipid and protein peroxidation whereas topiramate was found to reduce lipid peroxidation only.

CONCLUSIONS

An AED that produces anticonvulsant effect by the diversified mechanism of action such as levetiracetam, felbamate, and topiramate exhibited superior anti-oxidative stress activity in addition to their anticonvulsant activity.

[COMPARISON OF CHRONIC ANTICONVULSANT ACTIVITY AND SAFETY OF IEM-2062, SODIUM VALPROATE AND ME-MANTINE IN THE PENTYLENETETRAZOL KINDLING MODEL IN RATS]

IEM-2062 [1-(6-aminohexylamino)-1-phenylcyclohexyl dihydrochloride], causing a combined block NMDA and AMPA receptors, after chronic oral administration in doses, respectively, 0.3 and 3 mg/kg, induce maximal anticonvulsant effect in the pentylenetetrazol kindling rats because decrease the number of completely kindling rats by 100 %, and also decrease in 2.5-3.3 times the average severity of clonic-tonic kindling seizures. IEM-2062 causes significant anticon- 299 vulsant effects in the widest range of doses, 1-48 mg/kg, which is 24-22 times more than that of memantine (12-20 mg/kg) and sodium valproate (100-200 mg/kg). Sodium valproate and memantine cause significant disturbances of locomotor activity in the «open field» test in doses causing maximal anticonvulsant effect in the kindling rats. At the same time IEM-2062 cause disturbance of locomotor activity only in very high dose of 92 mg/kg, which exceeds in 30.7 times the dose causing the maximum anticonvulsive effect in the kindling rats. Thus, IEM-2062 reduces the severity of kindling seizures in 1.7-1.9 times stronger than sodium valproate and memantine and also by 30.7 times is safer than sodium valproate and memantine.

Anticonvulsant activity of an active fraction extracted from Crinum jagus L. (Amaryllidaceae), and its possible effects on fully kindled seizures, depression-like behaviour and oxidative stress in experimental rodent models

ETHNOPHARMACOLOGICAL RELEVANCE

The leaf extract of Crinum jagus L. (Amaryllidaceae) is widely used in traditional Cameroonian medicine as antiepileptic remedy and for the treatment of convulsion, depression and mood disorders associated with epilepsy.

AIM OF THE STUDY

Hence, this study was conducted to evaluate the effects of an active fraction extracted from the leaves of Crinum jagus against seizures, depression-like behaviour and oxidative stress in pentylenetetrazole (PTZ)-induced kindling in mice.

MATERIALS AND METHODS

Bioactive-guided fractionation of the leaf extract of Crinum jagus by using 70mg/kg PTZ-induced convulsions in mice, afforded a potent anticonvulsant fraction (flavonol kaempferol; C4.4). The effects of C4.4 on 30mg/kg PTZ-induced kindling, kindling-induced depression like-behaviour and oxidative stress was evaluated. Mice were injected PTZ (30mg/kg, i.p.) once every alternate day (48±1h) until the development of kindling. Depression was assessed using tail suspension test and forced swim test while the oxidative stress parameters were estimated in the whole brain at the end of experiments. Mice were submitted to the rota-rod task and open-field test in order to assess any non-specific muscle-relaxant or sedative effects of C4.4. Acute toxicity of C4.4 was also assessed in mice.

RESULTS

Convulsions-induced by 70mg/kg PTZ were strongly antagonized by C4.4. Oral administration of C4.4 significantly increased the latency to myoclonic jerks, clonic seizures as well as generalized tonic-clonic seizures, improved the seizure mean stage and decreased the number of myoclonic jerks in PTZ-kindled mice. The data indicated also that C4.4 significantly reduced the immobility times in the tail suspension test and the forced swim test. This active fraction has also antioxidant properties by decreasing the lipid peroxidation, and augmenting endogenous antioxidant enzymes in brain. C4.4 administered (12.5-50mg/kg) did not alter the locomotion of animals in the open-field or rotarod tests, which suggest a lack of a central depressant effect. The animals did not exhibit any acute toxicity to C4.4 at the therapeutic doses.

CONCLUSION

These results suggest that pretreatment with C4.4 ameliorates convulsions-induced by PTZ, protects mice against kindling development, depression-like behaviour and oxidative stress in PTZ-kindled mice. These finding provides scientific rationale for the use of Crinum jagus extracts for the amelioration of epilepsy observed in traditional medicine in Cameroon.

Pro-epileptogenic effects of viral-like inflammation in both mature and immature brains

BACKGROUND

Infectious 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.

METHODS

To 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.

RESULTS

PIC 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.

CONCLUSIONS

Hippocampal 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.

The Role of Inducible-Nitric Oxide in Cocaine-Induced Kindling

Experimentally naive male Sprague Dawley rats (weighing 85–110 g) were used to examine the role of inducible nitric oxide synthase (iNOS) in cocaine-induced kindling. Repeated administration of cocaine (45 mg/kg, ip) to Sprague Dawley male rats for 7 consecutive days produced a progressive increase in the Convulsive responsiveness and death. Pretreatment with iNOS inhibitors, L-N6-(1-iminoethyl)lysine (NIL; 10 mg/kg, ip) and (–)-ePigalloocatechin gallate (EGCG; 10 mg/kg, ip) 30 min before cocaine (45 mg/kg, ip) administration for 7 days attenuated the development of cocaine kindling and blocked cocaine-induced death. Results of NMDA receptor binding assay in the hippocampus showed a significant increase in the affinity without changes in the density in animals treated with cocaine, but there were no changes in these parameters in the cortex. Pretreatment with NIL or EGCG prior to cocaine administration abolished the cocaine-induced effect in the NMDA receptor affinity in the hippocampus. These results suggest that iNOS induction followed by an increase of NMDA receptor affinity in the hippocampus after repeated exposure to cocaine may participate in the process of the development of cocaine kindling.

Facilitation of Hippocampal Kindling and Exacerbation of Kindled Seizures by Intra-CA1 Injection of Quinine: A Possible Role of Cx36 Gap Junctions

BACKGROUND

GABAergic interneurons in the hippocampal CA1 area are mutually communicated by gap junctions (GJs) composed of connexin36 (Cx36). We examined the role of Cx36 in CA1 in manifestation of kindled seizures and hippocampal kindling in rats.

METHODS

Quinine, as the specific blocker of Cx36, was injected into CA1, and kindled seizures severity was examined 10 min afterward. Moreover, quinine was injected into CA1 once daily, and the rate of CA1 kindling was recorded.

RESULTS

Quinine 0.5 and 1 mM caused 2- and 3.5-fold increase in the duration of total seizure behavior and generalized the seizures. Primary and secondary afterdischarges (AD) were also significantly increased. Quinine 0.1 mM augmented the rate of kindling and the growth of secondary AD.

CONCLUSION

Cx36 GJs in CA1 are the main components of hippocampal inhibitory circuit. Any interruption in this path by pathologic or physical damages can trigger hippocampal hyperexcitability and facilitate epileptogenesis.

Anticonvulsant properties of methanol leaf extract of Laggera Aurita Linn. F. (Asteraceae) in laboratory animals

ETHNOPHARMACOLOGICAL RELEVANCE

Preparation of Laggera aurita Linn. (Asteraceae) is widely used in traditional medicine to treat various kinds of diseases such as epilepsy, malaria, fever, pain and asthma. Its efficacy is widely acclaimed among communities in Northern Nigeria.

AIM OF THE STUDY

The present study is aimed at establishing the possible anticonvulsant effects of the methanol leaf extract of Laggera aurita using acute and chronic anticonvulsant models.

MATERIALS AND METHOD

Median lethal dose (LD50) was determined in mice and rats via oral and intraperitoneal routes. Anticonvulsant screening of the extract was performed using maximal electroshock-induced seizure test in day-old chicks; pentylenetetrazole-, strychnine- and picrotoxin- induced seizure models in mice. Similarly; its effects on pentylenetetrazole-induce kindling in rats as well as when co-administered with fluphenamic and cyproheptadine in mice, were evaluated.

RESULTS

Median lethal dose (LD50) values were found to be >5000mg/kg, p.o. and 2154mg/kg, i.p., each for both rats and mice. The extract showed dose dependent protection against tonic hind limb extension (THLE) and significantly (p<0.05) decreased the mean recovery from seizure in the maximal electroshock-induced seizure. In the pentylenetetrazole-induced seizure model, the extract offered 50% protection at 600mg/kg and also increased the mean onset of seizure at all doses with significant (p<0.05) increase at the highest dose (600mg/kg). Similarly the extract produced significant (p<0.05) increase in the onset of seizures in both strychnine- and picrotoxin- induced seizure models, at all the doses except at 150mg/kg for the picrotoxin model. Co-administration of fluphenamic acid (FFA) (5mg/kg) and the extract (600mg/kg) showed an enhanced effect with percentage protection of 70% while co-administration of FFA (5mg/kg) and phenytoin (5mg/kg) as well phenytoin (5mg/kg) and the extract (600mg/kg) produced an additive effect. Administration of the extract (600mg/kg), phenytoin (20mg/kg) and cyproheptadine (4mg/kg) offered 40%, 100% and 0% protection against THLE, each respectively, while co-administration of cyproheptadine (4mg/kg) and the extract (600mg/kg) as well as co-administration of cyproheptadine (4mg/kg) and phenytoin (20mg/kg) offered reduced protection of 20% and 50% each respectively. The extract at all doses reduced the severity of seizure episodes induced by PTZ-induced kindling.

CONCLUSION

The results suggest that the methanol leaf extract of Laggera aurita possesses anticonvulsant and antiepileptogenic properties.

Critical Evaluation of P2X7 Receptor Antagonists in Selected Seizure Models

The ATP-gated P2X7 receptor (P2X7R) is a non-selective cation channel which senses high extracellular ATP concentrations and has been suggested as a target for the treatment of neuroinflammation and neurodegenerative diseases. The use of P2X7R antagonists may therefore be a viable approach for treating CNS pathologies, including epileptic disorders. Recent studies showed anticonvulsant potential of P2X7R antagonists in certain animal models. To extend this work, we tested three CNS-permeable P2X7R blocker (Brilliant Blue G, AFC-5128, JNJ-47965567) and a natural compound derivative (tanshinone IIA sulfonate) in four well-characterized animal seizure models. In the maximal electroshock seizure threshold test and the pentylenetetrazol (PTZ) seizure threshold test in mice, none of the four compounds demonstrated anticonvulsant effects when given alone. Notably, in combination with carbamazepine, both AFC-5128 and JNJ-47965567 increased the threshold in the maximal electroshock seizure test. In the PTZ-kindling model in rats, useful for testing antiepileptogenic activities, Brilliant Blue G and tanshinone exhibited a moderate retarding effect, whereas the potent P2X7R blocker AFC-5128 and JNJ-47965567 showed a significant and long-lasting delay in kindling development. In fully kindled rats, the investigated compounds revealed modest effects to reduce the mean seizure stage. Furthermore, AFC-5128- and JNJ-47965567-treated animals displayed strongly reduced Iba 1 and GFAP immunoreactivity in the hippocampal CA3 region. In summary, our results show that P2X7R antagonists possess no remarkable anticonvulsant effects in the used acute screening tests, but can attenuate chemically-induced kindling. Further studies would be of interest to support the concept that P2X7R signalling plays a crucial role in the pathogenesis of epileptic disorders.

NADPH oxidase activation is required for pentylenetetrazole kindling-induced hippocampal autophagy

Growing evidence indicates that alterations in autophagy are present in a variety of neurological disorders, ranging from neurodegenerative diseases to acute neurological insults. Only recently has the role of autophagy in epilepsy started to be recognized. In this study, we used pentylenetetrazole (PTZ) kindling, which provides a model of chronic epilepsy, to investigate the involvement of autophagy in the hippocampus and the possible mechanisms involved. Our western blot results showed that autophagy-related proteins were significantly increased after the mice were fully kindled. In addition, immunofluorescence studies revealed a significant increase in the punctate accumulation of LC3 in the hippocampal CA1 region of fully PTZ-kindled mice. Consistent with the upregulation of ATG proteins and punctate accumulation of LC3 in the hippocampal CA1 region, autophagosomal vacuole formation was observed by an ultrastructural analysis, verifying the presence of a hippocampal autophagic response in PTZ-kindled mice. Increased oxidative stress has been postulated to play an important role in the pathogenesis of a number of neurological diseases, including epilepsy. In this study, we demonstrate that PTZ kindling induced reactive oxygen species (ROS) production and lipid peroxidation, which were accompanied by mitochondrial ultrastructural damage due to the activation of NADPH oxidase. Pharmacological inhibition of NADPH oxidase by apocynin significantly suppressed the oxidative stress and ameliorated the hippocampal autophagy in PTZ-kindled mice. Interestingly, pharmacological induction of autophagy suppressed PTZ-kindling progress and reduced PTZ-kindling-induced oxidative stress while inhibition of autophagy accelerated PTZ kindling progress and increased PTZ-kindling-induced oxidative stress. These results suggest that the oxidative stress induced by NADPH oxidase activation may play a pivotal role in PTZ-kindling process as well as in PTZ kindling-induced hippocampal CA1 autophagy.

Effect of Liraglutide on Corneal Kindling Epilepsy Induced Depression and Cognitive Impairment in Mice

GLP-1 play important role in neuroprotection and GLP-1 receptor deficit mice showed decreased seizure threshold and increased cognitive impairment. Therefore, study was premeditated to investigate the effect of liraglutide (GLP-1 analogue) on cornel kindling epilepsy induced co-morbidities in mice. Corneal kindling was induced by electrical stimulation (6 mA, 50 Hz, 3 s); twice daily for 13 days. Liraglutide (75 and 150 µg/kg) and phenytoin (20 mg/kg) were administered in corneal kindled groups. On day 14, elevated plus maze, passive shock avoidance paradigms were performed, and on day 15, retention was taken. On day 16 tail suspension test were performed. On 20th day challenge test was performed with same electrical stimulation and retention was observed on elevated plus maze and passive avoidance paradigm. Animal were sacrificed on 21st day for biochemical (LPO, GSH, and nitrite) and neurochemical (GABA, glutamate, DA, NE, 5-HT and their metabolites) estimation. Electrical stimulation by corneal electrode for 13 days developed generalized clonic seizures, increased cognitive impairment, oxidative stress and neurochemical alteration in mice brain. Co-treatment with liraglutide (75 and 150 μg/kg) significantly prevented the seizure severity, restored behavioural activity, oxidative stress and restored the altered level of neurotransmitters observed in corneal kindled mouse.

Neurochemical modulation involved in the beneficial effect of liraglutide, GLP-1 agonist on PTZ kindling epilepsy-induced comorbidities in mice

Epilepsy is a neurological disorder which occurs due to excessive firing of excitatory neurons in specific region of brain and associated with cognitive impairment and depression. GLP-1 has been reported to maintain hyperexcitability of neurons. Therefore, this study was designed to investigate the neuroprotective effect of liraglutide, GLP-1 analogue in PTZ kindling epilepsy-induced comorbidities and neurochemical alteration in mice. Male albino mice were administered PTZ (35 mg/kg) on every alternate day up to 29th days and challenge test was performed on 33rd day. From 1st day liraglutide (75 and 150 µg/kg) and diazepam (3 mg/kg) were administered up to 33rd day, 30 min prior to PTZ treatment. On 30th day animals were trained on elevated plus maze and passive shock avoidance paradigm and retention was recorded on 31st and 33rd day. On 32nd day tail suspension test was performed. Animals were sacrificed on 34th day for biochemical (LPO, GSH, and nitrite) and neurotransmitters (GABA, glutamate, DA, NE, 5-HT and their metabolites) estimation. Chronic treatment with PTZ developed generalized tonic-clonic seizures, reduced cognitive skills, increased oxidative stress and alteration in the level of neurotransmitters. Pre-treatment with liraglutide (75 and 150 μg/kg) significantly prevented the seizure severity, restored behavioural activity, oxidative defence enzymes, and altered level of neurochemicals in mice brain. The protective effect of liraglutide is attributed to restoration of altered level of GABA, glutamate, DA, NE, and 5-HT by the up-regulation of GLP-1Rs in mice brain.

Antiapoptotic and neuroprotective role of Curcumin in Pentylenetetrazole (PTZ) induced kindling model in rat

Kindling, a sub threshold chemical or electrical stimulation, increases seizure duration and enhances accompanied behavior until it reaches a sort of equilibrium state. The present study aimed to explore the effect of curcumin on the development of kindling in PTZ kindled rats and its role in apoptosis and neuronal damage. In a PTZ kindled Wistar rat model, different doses of curcumin (100, 200 and 300 mg/kg) were administrated orally one hour before the PTZ injections on alternate day during the whole kindling days. The following parameters were compared between control and experimental groups: the course of kindling, stages of seizures, Histopathological scoring of hippocampus, antioxidant parameters in the hippocampus, DNA fragmentation and caspase-3 expression in hippocampus, and neuron-specific enolase in the blood. One way ANOVA followed by Bonferroni post hoc analysis and Fischer's Exact test were used for statistical analyses. PTZ, 30 mg/kg, induced kindling in rats after 32.0 ± 1.4 days. Curcumin showed dose-dependent anti-seizure effect. Curcumin (300 mg/kg) significantly increased the latency to myoclonic jerks, clonic seizures as well as generalized tonic-clonic seizures, improved the seizure score and decreased the number of myoclonic jerks. PTZ kindling induced a significant neuronal injury, oxidative stress and apoptosis which were reversed by pretreatment with curcumin in a dose-dependent manner. Our study suggests that curcumin has a potential antiepileptogenic effect on kindling-induced epileptogenesis.

Comparison of the after discharges induced by electrical stimulation of the prefrontal cortex in urethane- and ketamine-anesthetized mice

OBJECTIVE

The study aims to compare the effects of urethane and ketamine anesthesia on kindling-induced after discharges (AD).

MATERIALS AND METHODS

We divided forty 4-6 week old female C57BL/6J mice into two groups: one group was anesthetized with urethane (n = 20) and the other with ketamine (n = 20). Kindling was with an electrical stimulation (ES) consisting of a 1-s pulse train of 60 1-ms biphasic pulses at an initial intensity of 700 µA, delivered to the pre-frontal cortex every minute. Ten to fifteen minutes after the first AD was induced, identical electrical stimuli were delivered every 10 minutes for 200 minutes. EEG was continuously recorded from 15 minutes before the first ES until 10 minutes after the last ES. The EEG wave spectrum was analyzed by Fast Fourier Transform and the power spectrum densities (PSDs) of the δ, θ, α, β and γ bands were calculated. EEG wave amplitude was assessed using the root mean square value (RMS).

RESULTS

In the urethane group, an initial AD was induced in 70% of mice following 39 ES. In the ketamine group, an initial AD was induced in 60% of mice following 74 ES. The changes in EEG spectra were similar in both groups. Pre-AD, EEG waves predominantly consisted of δ and θ components. During AD, γ and β components increased significantly (p < 0.05). Post-AD, β and γ components decreased and the δ: θ ratio increased to pre-AD levels.

CONCLUSIONS

Our data suggest that AD can be induced by kindling stimulation of the pre-frontal cortex in mice under either urethane or ketamine anesthesia.

Increased sensitivity to kindling in mice lacking TSP1

The development of a hyperexcitable neuronal network is thought to be a critical event in epilepsy. Thrombospondins (TSPs) regulate synaptogenesis by binding the neuronal α2δ subunit of the voltage-gated calcium channel. TSPs regulate synapse formation during development and in the mature brain following injury. It is unclear if TSPs are involved in hyperexcitability that contributes to the development of epilepsy. Here we explore the development of epilepsy using a pentylenetetrazole (PTZ) kindling model in mice lacking TSP1 and TSP2. Unexpectedly, we found increased sensitivity to PTZ kindling in mice lacking TSP1, while mice lacking TSP2 kindled similar to wild-type. We found that the increased seizure susceptibility in the TSP1 knockout (KO) mice was not due to a compensatory increase in TSP2 mRNA as TSP1/2 KO mice were sensitive to PTZ, similar to the TSP1 KO mice. Furthermore, there were similar levels of TGF-B signal activation during kindling in the TSP1 KO mice compared to wild-type. We observed decreased expression of voltage-dependent calcium channel subunit CACNA2D1 mRNA in TSP1, TSP2, and TSP1/2 KO mice. Decreased CACNA2D2 mRNA was only detected in mice that lacked TSP1 and α2δ-1/2 protein levels in the cortex were lower in the TSP 1/2 KO mice. CACNA2D2 knockout mice have spontaneous seizures and increased PTZ seizure susceptibility. Here we report similar findings, TSP1, and TSP1/2 KO mice have low levels of CACNA2D2 mRNA expression and α2δ-1/2 receptor level in the cortex, and are more susceptible to seizures. CACNA2D2 mutations in mice and humans can cause epilepsy. Our data suggest TSP1 in particular may control CACNA2D2 levels and could be a modifier of seizure susceptibility.

Palmitoylethanolamide attenuates PTZ-induced seizures through CB1 and CB2 receptors

Epilepsy is one of the most common neurologic disorders. Though there are effective medications available to reduce the symptoms of the disease, their side effects have limited their usage. Palmitoylethanolamide (PEA) has been shown to attenuate seizure in different animal models. The objective of the current study was to evaluate the role of CB1 and CB2 receptors in this attenuation. Male wistar rats were used for the current experiment. PTZ was injected to induce chemical kindling in animals. After verification of kindling in animals, treatment was performed with PEA, AM251 and AM630 in different groups. Latency to induce seizure, seizure stages and latency and duration of fifth stage of seizure was recorded for each animal. Injection of PTZ led to seizure in the animals. Pretreatment with PEA increased the latency to initiate seizures and reduced the duration of seizure. Pretreatment with different dosages of AM251 had contrary effects so that at lower doses they increased the seizure in animals but at higher doses led to the attenuation of seizure. AM630 increased seizures in a dose dependent manner. Combination of the antagonists increased the seizure parameters and attenuated the effect of PEA on seizure. PEA attenuated the PTZ-induced seizures and pretreatment with CB1 and CB2 antagonists diminished this effect of PEA, but still PEA was effective, which might be attributed to the contribution of other receptors in PEA anti-epileptic properties. Findings of the current study implied that endocannabinoid signaling pathway might have an important role in the effects of PEA.

Z944, a Novel Selective T-Type Calcium Channel Antagonist Delays the Progression of Seizures in the Amygdala Kindling Model

Temporal lobe epilepsy (TLE) is the most common form of drug resistant epilepsy. Current treatment is symptomatic, suppressing seizures, but has no disease modifying effect on epileptogenesis. We examined the effects of Z944, a potent T-type calcium channel antagonist, as an anti-seizure agent and against the progression of kindling in the amygdala kindling model of TLE. The anti-seizure efficacy of Z944 (5mg/kg, 10mg/kg, 30mg/kg and 100mg/kg) was assessed in fully kindled rats (5 class V seizures) as compared to vehicle, ethosuximide (ETX, 100mg/kg) and carbamazepine (30mg/kg). Each animal received the seven treatments in a randomised manner. Seizure class and duration elicited by six post-drug stimulations was determined. To investigate for effects in delaying the progression of kindling, naive animals received Z944 (30mg/kg), ETX (100mg/kg) or vehicle 30-minutes prior to each kindling stimulation up to a maximum of 30 stimulations, with seizure class and duration recorded after each stimulation. At the completion of drug treatment, Ca_V3.1, Ca_V3.2 and Ca_V3.3 mRNA expression levels were assessed in the hippocampus and amygdala using qPCR. Z944 was not effective at suppressing seizures in fully kindled rats compared to vehicle. Animals receiving Z944 required significantly more stimulations to evoke a class III (p<0.05), IV (p<0.01) or V (p<0.0001) seizure, and to reach a fully kindled state (p<0.01), than animals receiving vehicle. There was no significant difference in the mRNA expression of the T-type Ca²⁺ channels in the hippocampus or amygdala. Our results show that selectively targeting T-type Ca²⁺ channels with Z944 inhibits the progression of amygdala kindling. This could be a potential for a new therapeutic intervention to mitigate the development and progression of epilepsy.

Antiepileptogenic, antioxidant and genotoxic evaluation of rosmarinic acid and its metabolite caffeic acid in mice

AIMS

Antioxidant compounds have been extensively investigated as a pharmacological alternatives to prevent epileptogenesis. Rosmarinic acid (RA) and caffeic acid (CA) are compounds with antioxidant properties, and RA has been shown to inhibit GABA transaminase activity (in vitro). Our aim was to evaluate the effect of RA and CA on seizures induced by pentylenotetrazole (PTZ) using the kindling model in mice.

MAIN METHODS

Male CF-1 mice were treated once every three days during 16days with RA (1, 2 or 4mg/kg; i.p.), or CA (1, 4 or 8mg/kg; i.p.), or positive controls diazepam (1mg/kg; i.p.) or vigabatrin (600mg/kg; p.o.), 30min before PTZ administration (50mg/kg; s.c.). After the last treatment, animals were sacrificed and the cortex was collected to evaluate free radicals (determined by 2',7'-dichlorofluorescein diacetate probe), superoxide dismutase (SOD) and genotoxic activity (Alkaline Comet Assay).

KEY FINDINGS

Rosmarinic acid 2mg/kg increased latency and decreased percentage of seizures, only on the 4th day of observation. The other tested doses of RA and CA did not show any effect. Rosmarinic acid 1mg/kg, CA 4mg/kg and CA 8mg/kg decreased free radicals, but no dose altered the levels of enzyme SOD. In the comet assay, RA 4mg/kg and CA 4mg/kg reduced the DNA damage index.

SIGNIFICANCE

Some doses of rosmarinic acid and CA tested showed neuroprotective action against oxidative and DNA damage produced in the kindling epilepsy model, although they did not produce antiepileptogenic effect in vivo.

Methanol extract of Ficus platyphylla ameliorates seizure severity, cognitive deficit and neuronal cell loss in pentylenetetrazole-kindled mice

Decoctions of Ficus plathyphylla are used in Nigeria's folk medicine to manage epilepsy for many years and their efficacies are widely acclaimed among the rural communities of Northern Nigeria. In this study, we examined the ameliorative effects of the standardized methanol extract of Ficus platyphylla (FP) stem bark on seizure severity, cognitive deficit and neuronal cell loss in pentylenetetrazole-kindled mice. The (35)S-GTPγS, glutamate and γ-aminobutyric acid receptors binding properties of the extract were also evaluated. Male CD-1 mice were kindled with an initial subeffective dose of pentylenetetrazole (PTZ, 37.5mg/kg, i.p.) for a total of 13 convulsant injections and the treatment groups concurrently received FP (100 and 200mg/kg). Control animals received the same number of saline injections. Twenty-four h after kindling completion the animals' learning performance was tested in a two-way shuttle-box. The animals were challenged with another subeffective dose of PTZ (32.5mg/kg, i.p.) on day 7 after kindling completion. Animals were sacrificed a day after the challenged experiment and the brains were processed for histological investigation. FP ameliorates seizure severity, cognitive deficits and neuronal cell loss in PTZ kindled mice. Components of the extract showed affinity for GABAergic and glutamatergic receptors. Glutamate release was diminished and the (35)S-GTPγS binding assay revealed no intrinsic activity at glutamatergic receptors. Our results revealed that FP contains psychoactive secondary metabolites with anticonvulsant properties, thus supporting the isolation and development of the biologically active components of this medicinal plant as antiepileptic agents.

[Effect of citicoline on the development of chronic epileptization of the brain (pentylenetetrazole kindling) and acute seizures reaction of kindled mice C57Bl/6]

In experiments on mice C57Bl/6 was studied effects of citicoline (500 mg/kg, i.p.) on development of chronically epileptization of the brain--pentylenetetrazole (PTZ) kindling (30 mg/kg PTZ, i.p. during 24 days) and on acute generalized seizures (i.v., 1% solution of PTZ with the speed of 0.01 ml/s). It was shown that daily injection of citicoline an hour before the introduction of PTZ had no effect on development of chronically epileptization of the brain --PTZ-kindling (the latency of seizures appearance and their severity). However, citicoIine posses anticonvulsive effects on acute seizures in kindled mice. In animals with increased seizure susceptibility of the brain caused by kindling and severity of seizures 2-3 points injection citicoline after 14 days of kindling had anticonvulsive effect, increasing the threshold clonic seizures. Injection of citicoline during 24 days of kindled animals and severity of seizures 3-5 points caused the increase of thresholds as clonic and tonic phase of seizures with lethal outcome. Thus, the anticonvulsant effect of citicoline more pronounced in the long-term use.

Effect of edaravone on apoptosis of hippocampus neuron in seizures rats kindled by pentylenetetrazole

OBJECTIVES

To explore the effect of edaravone (ED) on apoptosis of hippocampus neurons in seizures rats induced by pentylenetetrazole (PTZ).

MATERIALS AND METHODS

Forty-eight adult Wistar rats were randomly divided into normal control (NC) group, PTZ group, and ED group. A dose of PTZ [35 mg/(kg·day)] was intraperitoneally (i.p.) injected into the rats of PTZ group and ED group until the kindling criterion was reached. After kindling, the rats of ED group were administered i.p. with ED [0.8 mg/(kg·day)]; the rats of PTZ group were administered i.p. with normal saline. After 30 min, seizures were induced by administering PTZ i.p. The influence of ED on Fas, Caspase-3, and Survivin protein immunoreactivity on hippocampus neurons was studied by immunohistochemistry method.

RESULTS

Fas and Caspase-3 positive cells and optical density in hippocampus in PTZ group were more than that of ED group and NC group (all p < 0.01), but Survivin-positive cells and optical density in hippocampus in PTZ group were less than that of ED group (p < 0.01) and were more than that of NC group (p < 0.05); Fas- and Caspase-3-positive cells and optical density in hippocampus in ED group were more than that of NC group (all p < 0.05), but Survivin-positive cells and optical density in hippocampus in ED group were more than that of NC group (p < 0.01).

CONCLUSIONS

Seizure can induce apoptosis of hippocampus neurons on seizures rats, but ED can resist the apoptosis of hippocampus neurons by increased expression of Survivin and decreased expression of Fas and Caspase-3.

[Stimulation of gastric mucosa afferents by phenylephrine potentiates anticonvulsive and eliminates sedative action of sodium valproate in the pentylenetetrazol kindling model in rats]

Sodium valproate after chronic intragastric administration in the high dose of 100-200 mg/kg eliminates generalized clonic-tonic pentylenetetrazol seizures in 100 % of rats, but only in 33-57 % of rats it prevents local clonic kindling seizures. Strong sedation is induced by the specified doses of sodium valproate. The combined oral chronic administration of phenylephrine in threshold, noneffective alone dose of 0.2 mg/kg and sodium valproate in high doses of 100 mg/kg and 200 mg/kg potentiates anticonvulsive action of sodium valproate, because prevents both clonic-tonic kindling. seizures in 100 % of rats and clonic kindling seizures in 86-100 % of rats, and also it increases in 1.7-1.9 times anticonvulsive activity of valproate. The specified combinations of sodium valproate with phenylephrine do not produce the sedative side effect. The basis of the mechanism of potentiation of anticonvulsive action and elimination of sedative action of sodium valproate in high doses is the stimulation of gastric mucosa afferents by phenylephrine.

Anxiolytic and antidepressive effects of electric stimulation of the paleocerebellar cortex in pentylenetetrazol kindled rats

Anxiety and depression are component of interictal behavioral deteriorations that occur as a consequence of kindling, a procedure to induce chronic epilepsy. The aim of this study was to evaluate the possible effects of electrical stimulation (ES) of paleocerebellar cortex on anxiety and depressive-like behavior in a PTZ kindled epilepsy model. Kindling was induced via pentylenetetrazol (PTZ) (25.0 mg/kg IP daily) during three weeks. Locomotion in open field, elevated plus-maze (EPM) and Porsolt forced swimming test have been used for the assessment of anxiety and depression-like behavior. ES (100 Hz) has been delivered to V-VII lobules of vermal cortex of kindled rats. ES of paleocerebellum reversed kindling-induced reduction of crossings of central squares, increased rearings, and decreased the number of defecations in open field. The duration that kindled animals spent in the open arms of the EPM increased in post- ES period, and the number of enterings into the closed arms of the EPM decreased. The duration of the immobility response in the swimming test in kindled rats was reduced after ESs of paleocerebellum. In all: ES of paleocerebellar structures suppressed anxious and depressive-like behavior in PTZ-kindled rats.

A novel kindling model of temporal lobe epilepsy in rhesus monkeys induced by Coriaria lactone

One of the major challenges in developing novel therapeutics for human epileptic disorders derives from the limitation of knowledge of the processes by which epilepsy is generated (epileptogenesis). Furthermore, the inability to obtain human samples at the early stage of epilepsy hinders studies designed to further understand epileptogenesis. Thus, an effective animal model is critical for studies investigating this process. The purpose of this study was to establish a new primate kindling model of temporal lobe epilepsy (TLE) as an animal model of epileptogenesis. Here, repeated injections of Coriaria lactone (CL) at a subthreshold dose elicited partial seizures that culminated in secondarily generalized tonic-clonic seizures. The sequence of events and features of the behaviors observed in this model simulated those observed in human TLE. Electroencephalogram monitoring revealed the temporal lobe origins of the epileptiform potentials, which were consistent with the behavioral changes observed. A total of 7 rhesus monkeys (78%) were kindled with a median of 48 (41 to 60) CL injections. Both the seizure-induction and mortality rates were dose-dependent. A CL injection at 1.50mg/kg showed the lowest animal mortality rate (0%) and the highest seizure-induction rate (100%). Extensive kindling by CL injections with a median of 97 injections (overkindling) subsequently resulted in the recurrence of spontaneous seizures in rhesus monkeys with frequency patterns that were similar to those observed in human TLE. In addition, rhesus monkeys subjected to large numbers of kindling stimuli displayed mitochondrial damage and astrocyte activation in a pattern that was similar to the neuropathological changes characteristic of human TLE. Thus, a kindling TLE model in rhesus monkeys representing a primate animal model of epileptogenesis was established for the first time using repeated intramuscular injections of Coriaria lactone. This model was easily and efficiently performed and resulted in behavioral, electrographical, and anatomical characteristics of human TLE. Thus, this model might be used in future investigations of the mechanisms involved in the epileptogenesis of TLE and in the development of new antiepileptic drugs.