Animal Models Of Seizures Research Articles

Anticonvulsant activity, crystal structures, and preliminary safety evaluation of N-trans-cinnamoyl derivatives of selected (un)modified aminoalkanols

Adequate control of seizures remains an unmet need in epilepsy. In order to identify new anticonvulsant agents, a series of N-trans-cinnamoyl derivatives of selected aminoalkanols was synthetized. The compounds were obtained in the reaction of N-acylation carried out in a two-phase system. The substances were tested in animal models of seizures induced either electrically (maximal electroshock – MES; 6-Hz test) or chemically, by subcutaneous injection of pentetrazol (scPTZ). Neurotoxicity was determined by the rotarod test. Lipophilicity of the active compounds, expressed as RM0, was determined by reversed-phase thin layer chromatography and it ranged from 1.390 to 2.219. From among the tested series of compounds, R,S-(E)-N-(1-hydroxypropan-2-yl)-3-phenylprop-2-enamide (1) and R,S-(E)-N-(2-hydroxypropyl)-3-phenylprop-2-enamide (3) exhibited the best anticonvulsant activity. Compound 1, when administered to mice by intraperitoneal (i.p.) injection, showed the ED50 values of 86.6, 60.9, and 109.6 mg/kg in the MES, 6-Hz, and scPTZ tests, respectively. For compound 3, the ED50 values were found to be 47.1 mg/kg in MES and 77.1 mg/kg in scPTZ (mice, i.p.). The distances measured in crystals of compound 1 were: 7.99 Å – from the phenyl ring to the hydroxyl group in the amide moiety, 5.729 Å – from the phenyl ring to the amide group, and 3.112 Å – from the amide group to the hydroxyl group in the amide moiety. The reported compounds did not exhibit mutagenic potential when assayed in the Ames test. Compounds 1 and 3 did not affect viability and morphology of human hepatocellular carcinoma cells (HepG2).

Translating Nature to Nurture: Back to the Future for "New" Epilepsy Therapies.

An emerging strategy for finding new epilepsy therapies is focused on botanicals (as illustrated by recent attention to medical marijuana), given their centuries-old traditions of use in treatment of convulsive seizures, contemporary anecdotal reports of efficacy in persons with epilepsy, and identification of underlying mechanisms of action that are relevant to epilepsy. Hundreds of plant extracts have been found to block seizures in acute animal seizure models, with actions that include effects on GABA receptors and voltage-gated ion channels as well as anti-inflammatory and neuroprotective effects. While existing published clinical studies of botanicals and seizure control are generally of inadequate quality to determine safety and efficacy, recent developments at the FDA may encourage sponsors to develop and commercialize botanicals for epilepsy.

Anticonvulsant and behavioral effects observed in mice following treatment with an ester derivative of ferulic acid: Isopentyl ferulate

The objective of this study was to evaluate the potential anticonvulsant effect of isopentyl ferulate, a new ester derived from ferulic acid in mice (Mus musculus) subjected to two models of induced seizures. According to the results obtained, the IF at doses of 25, 50 and 75 mg/kg (i.p.) showed protective effect against induced seizures by pilocarpine (400 mg/kg, i.p.) and pentylenetetrazole (70 mg/kg, i.p.). In the two animal models of seizures, the pretreatment of the IF (25, 50 and 75 mg/kg) with flumazenil blocked the anticonvulsant effect, suggesting that the mechanism of action of this ester derived of ferulic acid may be related to activity in the benzodiazepine-binding site of the GABAA receptor (γ-aminobutyric acid, type A). In addition to the anticonvulsant effect, behavioral changes as neurotoxicity indication were assessed by using the rota rod and open field tests. The results obtained showed that the IF (25, 50 and 75 mg/kg) does not induce significant changes in locomotor activity and motor coordination when compared with the control group, unlike the results presented by diazepam. Thus, these results demonstrate a new pharmacological knowledge of IF with potential application against epileptic seizures. However, further studies are needed to elucidate other neurobiological mechanisms underlying epilepsy.

Protective action of nicotinic acid benzylamide in a variety of chemically-induced seizures in mice.

The study aims to assess the anticonvulsant effects offered by benzylamide nicotinic acid (Nic-BZA) in many animal models of chemically-induced seizures (i.e., pentylenetetrazole [PTZ], pilocarpine [PILO], bicuculline [BIC], α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA], kainic acid [KA], and N-methyl-d-aspartic acid [NMDA]). Additionally, it analyses side effects of administering Nic-BZA in the form of loss of co-ordination and memory impairment as evaluated in the rotarod and passive avoidance tests, respectively. Antiseizure activity of Nic-BZA was reported in numerous models of chemically-induced seizures and its ED50 value was 37.1mg/kg for PTZ, 53.0mg/kg for AMPA, 81.4mg/kg for BIC, 86.3mg/kg for KA, and 182.6mg/kg for PILO. Moreover, Nic-BZA was totally ineffective (in dosages of up to 200mg/kg) in mice challenged with NMDA-induced seizures. The evaluation of the side effects present shortly after dosing in the rotarod test has revealed neurotoxicity of Nic-BZA with experimentally determined TD50 value of 188.5mg/kg. Protective index (PI) assessment analysis for Nic-BZA has disclosed a substantial difference between the dosage resulting in acute impairment of co-ordination and the dosage resulting in anticonvulsant effect in various chemically evoked seizures, remaining practically ineffective (in dosages of up to 200mg/kg) in mice subjected to the NMDA-induced seizure test. Additionally, Nic-BZA (in dosages of up to 100mg/kg) did not impair long-term memory in mice. Summing up, Nic-BZA has a wide anticonvulsant effect in different experimental epilepsy models.

On the anticonvulsant effect of allopregnanolone (a neurosteroid) in neonatal rats.

Allopregnanolone has shown potent anticonvulsant activity in the adult brain. However, none of the studies have shown its effect in neonatal animal models of seizures. The current study explored the effect of allopregnanolone in animal models of neonatal status epilepticus. Allopregnanolone was administered 10min before administration of kainic acid or 4-aminopyridine in postnatal 9 (PN9) day old rats. Various phases of convulsions such as latency to myoclonic jerks, continuous clonic movements with loss of righting reflex (status epilepticus) and mortality were measured; the effect was compared with its effect in pentylenetetrazol (PTZ) -induced generalized tonic-clonic convulsions. Exogenous administration of kainic acid (2mg/kg., i.p.) or 4-aminopyridine (5mg/kg., i.p.) in rat pups (PN9) resulted in continuous clonic movements with loss of righting reflex (status epilepticus). Pre-treatment with allopregnanolone at doses of 5 and 10mg/kg., i.p. dose-dependently delayed the onset of status epilepticus, but not myoclonic jerks. Allopregnanolone did not prevent kainic acid-induced mortality at theses doses. In the kainic acid model, pretreatment of bumetanide before allopregnanolone delayed various phases of convulsions; the effect was significantly higher compared to per se groups. Allopregnanolone only at the higher dose extended the latency of 4-aminopyridine-induced seizures. In contrast, allopregnanolone at a low dose markedly shielded neonatal rats against PTZ convulsions. Allopregnanolone is protective in animal models of neonatal status epilepticus and generalized tonic-clonic convulsions and further clinical studies are required to establish its use in therapeutics.

Effects of Chronic Lamotrigine Administration on Maximal Electroshock- Induced Seizures in Mice.

The aim of the study was to determine anticonvulsant activity of lamotrigine (LTG) after acute and chronic treatment in four different protocols against maximal electroshock-induced seizures in mice. Such a knowledge seems to be valuable in view of the fact that all interactions between LTG and other drugs are evaluated in acute, not chronic, experiments. Electroconvulsions were produced by means of alternating current (50 Hz, 25 mA, 0.2 s) delivered via ear-clip electrodes. Motor impairment and long-term memory deficits in animals were assessed in the chimney test and in passive avoidance task, respectively. Brain and plasma concentrations of LTG were measured by HPLC. Chronic treatment with LTG (2 injections for 14 days) significantly potentiated the anticonvulsant effects of this antiepileptic in the maximal electroshock test in mice, significantly decreasing ED50 value for this antiepileptic. No impairment in motor coordination or long-term memory after acute or chronic treatment with LTG was noted. Nevertheless, prolonged treatment aggravated toxicity of LTG assessed in the chimney test as TD50 value. Repeated administration of LTG significantly increased plasma and brain concentrations of the antiepileptic drug when compared to the control group (single drug application). In conclusion, anticonvulsant action of LTG in the maximal electroshock test in mice may change, depending on the length of therapy. Both acute and chronic protocols are necessary in preclinical assessment of the anticonvulsant effects of drugs and possible interactions between them.

Long-term Continuous EEG Monitoring in Small Rodent Models of Human Disease Using the Epoch Wireless Transmitter System

Many progressive neurologic diseases in humans, such as epilepsy, require pre-clinical animal models that slowly develop the disease in order to test interventions at various stages of the disease process. These animal models are particularly difficult to implement in immature rodents, a classic model organism for laboratory study of these disorders. Recording continuous EEG in young animal models of seizures and other neurological disorders presents a technical challenge due to the small physical size of young rodents and their dependence on the dam prior to weaning. Therefore, there is not only a clear need for improving pre-clinical research that will better identify those therapies suitable for translation to the clinic but also a need for new devices capable of recording continuous EEG in immature rodents. Here, we describe the technology behind and demonstrate the use of a novel miniature telemetry system, specifically engineered for use in immature rats or mice, which is also effective for use in adult animals.

Long-term Continuous EEG Monitoring in Small Rodent Models of Human Disease Using the Epoch Wireless Transmitter System.

Many progressive neurologic diseases in humans, such as epilepsy, require pre-clinical animal models that slowly develop the disease in order to test interventions at various stages of the disease process. These animal models are particularly difficult to implement in immature rodents, a classic model organism for laboratory study of these disorders. Recording continuous EEG in young animal models of seizures and other neurological disorders presents a technical challenge due to the small physical size of young rodents and their dependence on the dam prior to weaning. Therefore, there is not only a clear need for improving pre-clinical research that will better identify those therapies suitable for translation to the clinic but also a need for new devices capable of recording continuous EEG in immature rodents. Here, we describe the technology behind and demonstrate the use of a novel miniature telemetry system, specifically engineered for use in immature rats or mice, which is also effective for use in adult animals.

Activation of CB2 receptor is required for the therapeutic effect of ABHD6 inhibition in experimental autoimmune encephalomyelitis

Alpha/beta-hydrolase domain 6 (ABHD6) is a novel 2-arachidonoylglycerol (2-AG) hydrolytic enzyme, that can fine-tune the endocannabinoid signaling in the central nervous system. Recently we and others have demonstrated the protective effect of ABHD6 inhibition in the animal models of traumatic brain injury and epileptic seizures. In this study, we investigated the role of targeting ABHD6 in experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). Post-symptom treatment with an ABHD6 inhibitor WWL70 increased the brain levels of 2-AG and ameliorated the clinical signs of EAE, T cells infiltration, microglia activation and the expression of activated leukocyte cell adhesion molecules. The production of iNOS, COX-2, TNF-α and IL-1β and the phosphorylation of NF-κB were also significantly reduced by WWL70 treatment. The neuroprotective effect of WWL70 was demonstrated by increased survival of mature oligodendrocytes, reduced demyelination and axonal loss in WWL70 treated EAE mouse spinal cord. The therapeutic effect of WWL70 on EAE was absent by co-administration of CB2 receptor antagonist, but not CB1 receptor antagonist. Consistently, WWL70 did not afford any protection in CB2 receptor knockout mice after EAE induction. Given the increased expression of ABHD6 in microglia/macrophages, but not in T cells, we speculated that inhibition of ABHD6 might enhance 2-AG signaling particularly in microglia/macrophages to exert anti-inflammatory effects via activation of CB2 receptors. These results suggest that inhibition of ABHD6 might be used as an ideal strategy for the treatment of MS and other neurodegenerative diseases.

GABAA currents are decreased by IL-1β in epileptogenic tissue of patients with temporal lobe epilepsy: implications for ictogenesis

Temporal lobe epilepsy (TLE) is the most prevalent form of adult focal onset epilepsy often associated with drug-resistant seizures. Numerous studies suggest that neuroinflammatory processes are pathologic hallmarks of both experimental and human epilepsy. In particular, the interleukin (IL)-1β/IL-1 receptor type 1 (R1) axis is activated in epileptogenic tissue, where it contributes significantly to the generation and recurrence of seizures in animal models. In this study, we investigated whether IL-1β affects the GABA-evoked currents (IGABA) in TLE tissue from humans. Given the limited availability of fresh human brain specimens, we used the “microtransplantation” method of injecting Xenopus oocytes with membranes from surgically resected hippocampal and cortical tissue from 21 patients with TLE and hippocampal sclerosis (HS), hippocampal tissue from five patients with TLE without HS, and autoptic and surgical brain specimens from 15 controls without epilepsy. We report the novel finding that pathophysiological concentrations of IL-1β decreased the IGABA amplitude by up to 30% in specimens from patients with TLE with or without HS, but not in control tissues. This effect was reproduced by patch-clamp recordings on neurons in entorhinal cortex slices from rats with chronic epilepsy, and was not observed in control slices. In TLE specimens from humans, the IL-1β effect was mediated by IL-1R1 and PKC. We also showed that IL-1R1 and IRAK1, the proximal kinase mediating the IL-1R1 signaling, are both up-regulated in the TLE compared with control specimens, thus supporting the idea that the IL-1β/IL-R1 axis is activated in human epilepsy. Our findings suggest a novel mechanism possibly underlying the ictogenic action of IL-1β, thus suggesting that this cytokine contributes to seizure generation in human TLE by reducing GABA-mediated neurotransmission.

Initiation, Propagation, and Termination of Partial (Focal) Seizures

The neurophysiological patterns that correlate with partial (focal) seizures are well defined in humans by standard electroencephalogram (EEG) and presurgical depth electrode recordings. Seizure patterns with similar features are reproduced in animal models of partial seizures and epilepsy. However, the network determinants that support interictal spikes, as well as the initiation, progression, and termination of seizures, are still elusive. Recent findings show that inhibitory networks are prominently involved at the onset of these seizures, and that extracellular changes in potassium contribute to initiate and sustain seizure progression. The end of a partial seizure correlates with an increase in network synchronization, which possibly involves both excitatory and inhibitory mechanisms.

Computer-Aided Identification of Anticonvulsant Effect of Natural Nonnutritive Sweeteners Stevioside and Rebaudioside A.

Steviol glycosides are natural constituents of Stevia rebaudiana (Bert.) Bert. (Asteraceae) that have recently gained worldwide approval as nonnutritive sweeteners by the Joint Food and Agriculture Organization/World Organization Expert Committee on Food Additives. Cheminformatic tools suggested that the aglycone steviol and several of its phase I metabolites were predicted as potential anticonvulsant agents effective in the seizure animal model maximal electroshock seizure (MES) test. Thus, aqueous infusion from S. rebaudiana was tested in the MES test (mice, intraperitoneal administration), confirming dose-dependent anticonvulsant effect. Afterward, isolated stevioside and rebaudioside A were tested in the MES test, with positive results. Though drug repositioning most often focuses on known therapeutics, this article illustrates the possibilities of this strategy to find new functionalities and therapeutic indications for food constituents and natural products.

A pharmacological basis of herbal medicines for epilepsy.

Epilepsy is the most common chronic neurological disease, affecting about 1% of the world's population during their lifetime. Most people with epilepsy can attain a seizure-free life upon treatment with antiepileptic drugs (AEDs). Unfortunately, seizures in up to 30% do not respond to treatment. It is estimated that 90% of people with epilepsy live in developing countries, and most of them receive no drug treatment for the disease. This treatment gap has motivated investigations into the effects of plants that have been used by traditional healers all over the world to treat seizures. Extracts of hundreds of plants have been shown to exhibit anticonvulsant activity in phenotypic screens performed in experimental animals. Some of those extracts appear to exhibit anticonvulsant efficacy similar to that of synthetic AEDs. Dozens of plant-derived chemical compounds have similarly been shown to act as anticonvulsants in various in vivo and in vitro assays. To a significant degree, anticonvulsant effects of plant extracts can be attributed to widely distributed flavonoids, (furano)coumarins, phenylpropanoids, and terpenoids. Flavonoids and coumarins have been shown to interact with the benzodiazepine site of the GABAA receptor and various voltage-gated ion channels, which are targets of synthetic AEDs. Modulation of the activity of ligand-gated and voltage-gated ion channels provides an explanatory basis of the anticonvulsant effects of plant secondary metabolites. Many complex extracts and single plant-derived compounds exhibit antiinflammatory, neuroprotective, and cognition-enhancing activities that may be beneficial in the treatment of epilepsy. Thus, botanicals provide a base for target-oriented antiepileptic drug discovery and development. In the future, preclinical work should focus on the characterization of the effects of plant extracts and plant-derived compounds on well-defined targets rather than on phenotypic screening using in vivo animal models of acute seizures. At the same time, available data provide ample justification for clinical studies with selected standardized botanical extracts and plant-derived compounds. This article is part of a Special Issue entitled "Botanicals for Epilepsy".

Synergistic effect of docosahexaenoic acid on anticonvulsant activity of valproic acid and lamotrigine in animal seizure models.

Add-on therapy is a common strategy to improve efficacy and tolerability of antiepileptic drugs (AEDs). Anticonvulsant potential and appropriate safety of docosahexaenoic acid (DHA) makes it a promising candidate for combination therapy. We evaluated influence of DHA on anticonvulsant activity of AEDs phenytoin, valproate, and lamotrigine in maximal electroshock (MES), pentylenetetrazole (PTZ), and kindling models of epilepsy. The dose-response to DHA was obtained 15min after intracerebroventricular (i.c.v.) injection in PTZ model of clonic seizures in mice, MES model of tonic seizures in mice, and kindling model of complex partial seizures in rats. The dose-response curve of valproate (30min after i.p. injection to mice) in PTZ, phenytoin (60min after i.p. injection to mice) in MES, and lamotrigine (60min after i.p. injection to rats) in kindling models were obtained. Dose-response curves of the AEDs were then achieved in the presence of ED25 of DHA. DHA had no anticonvulsant effect in the MES model. However, it showed a dose-dependent protective effect against PTZ (ED50=0.13μM) and kindled seizures (ED50=1.08mM). DHA at ED25 caused a 3.6-fold increase in potency of valproate as its ED50 value from 117.5 (98.3-135.3) decreased to 32.5(21.6-44.1)mg/kg. Moreover, a 4.9-fold increase in potency of lamotrigine occurred, as its ED50 value from 13.10 (11.50-14.9) decreased to 2.65(0.8-5.6)mg/kg. CompuSyn analysis indicated synergistic anticonvulsant interaction between DHA and both valproate and lamotrigine. Co-administration strategy of the safe and inexpensive anticonvulsant compound DHA with AEDs should be favorably regarded in clinical studies of epilepsy treatment.

Hyperthermia-induced seizures alter adenosine A1 and A2A receptors and 5'-nucleotidase activity in rat cerebral cortex.

Febrile seizure is one of the most common convulsive disorders in children. The neuromodulator adenosine exerts anticonvulsant actions through binding adenosine receptors. Here, the impact of hyperthermia-induced seizures on adenosine A1 and A2A receptors and 5'-nucleotidase activity has been studied at different periods in the cerebral cortical area by using radioligand binding, real-time PCR, and 5'-nucleotidase activity assays. Hyperthermic seizures were induced in 13-day-old rats using a warmed air stream from a hair dryer. Neonates exhibited rearing and falling over associated with hindlimb clonus seizures (stage 5 on Racine scale criteria) after hyperthermic induction. A significant increase in A1 receptor density was observed using [(3) H]DPCPX as radioligand, and mRNA coding A1 was observed 48h after hyperthermia-induced seizures. In contrast, a significant decrease in A2A receptor density was detected, using [(3) H]ZM241385 as radioligand, 48h after hyperthermia-evoked convulsions. These short-term changes in A1 and A2A receptors were also accompanied by a loss of 5'-nucleotidase activity. No significant variations either in A1 or A2A receptor density or 5'-nucleotidase were observed 5 and 20days after hyperthermic seizures. Taken together, both regulation of A1 and A2A receptors and loss of 5'-nucleotidase in the cerebral cortex suggest the existence of a neuroprotective mechanism against seizures. Febrile seizure is one of the most common convulsive disorders in children. The consequences of hyperthermia-induced seizures (animal model of febrile seizures) on adenosine A1 and A2A receptors and 5'-nucleotidase activity have been studied at different periods in cerebral cortical area. A significant increase in A1 receptor density and mRNA coding A1 was observed 48h after hyperthermia-induced seizures. In contrast, a significant decrease in A2A receptor density and 5'-nucleotidase activity was detected 48h after convulsions evoked by hyperthermia. These changes suggest the possible existence of a neuroprotective mechanism against seizures.

Is there a relationship between sweet taste and seizures? Anticonvulsant and proconvulsant effects of non-nutritive sweeteners.

From a virtual screening campaign, a number of artificial and natural sweeteners were predicted as potential anticonvulsant agents with protective effects in the seizure animal model Maximal Electroshock Seizure (MES) test. In all cases, the predictions were experimentally confirmed in the aforementioned preclinical seizure model. The article reviews and expands previous reports from our group on anticonvulsant activity of those non-nutritive sweeteners, illustrating the potential of virtual screening approaches to propose new medical uses of food additives. This constitutes a particular case of knowledge-based drug repositioning, which may greatly shorten the development time and investment required to introduce novel medications to the pharmaceutical market. We also briefly overview evidence on possible molecular explanations on the anticonvulsant and proconvulsant effects of different non-nutritive sweeteners. Our analysis -based on Swanson's ABC model- suggests that group I metabotropic glutamate receptors and carbonic anhydrase isoform VII (both proposed or validated molecular targets of antiepileptic drugs) might be involved in the anticonvulsant effect of artificial sweeteners. The first hypothesis is in line with recent advances on development of selective modulators of group I metabotropic glutamate receptors as potential antiepileptic agents.

Chimeric derivatives of functionalized amino acids and α-aminoamides: Compounds with anticonvulsant activity in seizure models and inhibitory actions on central, peripheral, and cardiac isoforms of voltage-gated sodium channels

Six novel 3″-substituted (R)-N-(phenoxybenzyl) 2-N-acetamido-3-methoxypropionamides were prepared and then assessed using whole-cell, patch-clamp electrophysiology for their anticonvulsant activities in animal seizure models and for their sodium channel activities. We found compounds with various substituents at the terminal aromatic ring that had excellent anticonvulsant activity. Of these compounds, (R)-N-4′-((3″-chloro)phenoxy)benzyl 2-N-acetamido-3-methoxypropionamide ((R)-5) and (R)-N-4′-((3″-trifluoromethoxy)phenoxy)benzyl 2-N-acetamido-3-methoxypropionamide ((R)-9) exhibited high protective indices (PI=TD50/ED50) comparable with many antiseizure drugs when tested in the maximal electroshock seizure test to mice (intraperitoneally) and rats (intraperitoneally, orally). Most compounds potently transitioned sodium channels to the slow-inactivated state when evaluated in rat embryonic cortical neurons. Treating HEK293 recombinant cells that expressed hNaV1.1, rNaV1.3, hNaV1.5, or hNaV1.7 with (R)-9 recapitulated the high levels of sodium channel slow inactivation.

Ceruloplasmin is an endogenous protectant against kainate neurotoxicity

To determine the role of ceruloplasmin (Cp) in epileptic seizures, we used a kainate (KA) seizure animal model and examined hippocampal samples from epileptic patients. Treatment with KA resulted in a time-dependent decrease in Cp protein expression in the hippocampus of rats. Cp-positive cells were colocalized with neurons or reactive astrocytes in KA-treated rats and epileptic patient samples. KA-induced seizures, initial oxidative stress (i.e., hydroxyl radical formation, lipid peroxidation, protein oxidation, and synaptosomal reactive oxygen species), altered iron status (increasing Fe2+ accumulation and L-ferritin-positive reactive microglial cells and decreasing H-ferritin-positive neurons), and impaired glutathione homeostasis and neurodegeneration (i.e., Fluoro-Nissl and Fluoro-Jade B staining analyses) were more pronounced in Cp antisense oligonucleotide (ASO)- than in Cp sense oligonucleotide-treated rats. Consistently, Cp ASO facilitated KA-induced lactate dehydrogenase (LDH) release, Fe2+ accumulation, and glutathione loss in neuron-rich and mixed cultures. However, Cp ASO did not alter KA-induced LDH release or Fe2+ accumulation in the astroglial culture, but did facilitate impairment in glutathione homeostasis in the same culture. Importantly, treatment with human Cp protein resulted in a significant attenuation against these neurotoxicities induced by Cp ASO. Our results suggest that Cp-mediated neuroprotection occurs via the inhibition of seizure-associated oxidative damage (including impairment in glutathione homeostasis), Fe2+ accumulation, and alterations in ferritin immunoreactivity. Moreover, interactive modulation between neurons and glia was found to be important for Cp upregulation in the attenuation of epileptic damage in both animals and humans.

Astrocyte-neuronal interactions in epileptogenesis.

Pentylenetetrazol, kainic acid, or pilocarpine can be used to induce seizures in animal models of epilepsy. The present Review describes disturbances in astrocyte-neuron interactions in the acute, latent, and chronic phases analyzed by magnetic resonance spectroscopy of brain tissue extracts from rats injected with [1-(13)C]glucose and [1,2-(13)C]acetate. The most consistent change after onset of seizures was the decrease in (13)C labeling of glutamate (GLU) from [1-(13) C]glucose regardless of brain area, severity, or duration of the period with seizures and toxin used. In most cases this decrease was accompanied by a reduction in glutamine (GLN) labeling from [1-(13)C]glucose, presumably as a direct consequence of the reduction in labeling of GLU and the GLU-GLN cycle. Amounts of GLN were never changed. Reduction in the content of N-acetyl aspartate (NAA) was first detectable some time after status epilepticus but before the occurrence of spontaneous seizures. This decrease can be an indication of neuronal death and/or mitochondrial impairment and might indicate beginning gliosis. It is known that gliosis occurs in the chronic phase of temporal lobe epilepsy in hippocampus, but astrocyte metabolism appears normal in this phase, indicating that the gliotic astrocytes have a somewhat reduced metabolism per volume. A decrease in (13)C labeling of GLU from [1-(13)C]glucose is a very sensitive measure for the onset of epileptogenesis, whereas reduction of NAA is first detectable later. In the chronic phases of the hippocampal formation, astrocyte metabolism is upregulated given that the number of neurons is reduced.

α-Spinasterol, a TRPV1 receptor antagonist, elevates the seizure threshold in three acute seizure tests in mice.

α-Spinasterol is a plant-derived compound which was reported to act as a selective antagonist for the transient receptor potential vanilloid 1 (TRPV1) receptor. Several studies revealed that the TRPV1 receptors might modulate seizure activity in animal models of seizures and epilepsy. The aim of the present study was to investigate the effect of α-spinasterol on the seizure threshold in three acute models of seizures, i.e., in the intravenous (i.v.) pentylenetetrazole (PTZ) seizure test, in the maximal electroshock seizure threshold (MEST) test and in the model of psychomotor seizures induced by 6 Hz stimulation in mice. Our results revealed significant anticonvulsant effect of α-spinasterol in all the used seizure tests. In the i.v. PTZ test, statistically significant elevation was noted in case of the threshold for myoclonic twitches (doses of 0.1–1 mg/kg) and generalized clonus seizures (doses of 0.5 and 1 mg/kg) but not for tonic seizures. The studied TRPV1 antagonist also increased the threshold for tonic hindlimb extension in the MEST (doses of 0.5 and 1 mg/kg) and 6 Hz psychomotor seizure (doses of 0.1 and 0.5 mg/kg) tests in mice. Furthermore, α-spinasterol did not produce any significant impairment of motor coordination (assessed in the chimney test) and muscular strength (investigated in the grip-strength test) and it did not provoke significant changes in body temperature in mice. Based on the results of our study and the fact that α-spinasterol is characterized by good blood–brain permeability, we postulate further investigation of this compound to precisely evaluate mechanism of its anticonvulsant action and opportunity of its usage in clinical practice.