Reduced Seizure Severity Research Articles

Adjuvant quercetin therapy for combined treatment of epilepsy and comorbid depression

Epilepsy is one of the major neurological disorders frequently associated with psychiatric disorders such as depression. The predisposition of tryptophan metabolism towards kynurenine pathway has been reported as one of the plausible reasons for association of depression in epilepsy. Hence, this study was envisaged to evaluate the dose dependent inhibition of indoleamine 2,3-dioxygenase (IDO) enzyme employing quercetin (screened employing in vitro method) with levetiracetam for combined management of epilepsy and comorbid depression. Kindling was induced in male swiss albino mice by administration of pentylenetetrazole subconvulsive doses (35 mg/kg, i.p.) at an interval of 48 ± 2 h. Kindled animals were treated with vehicle, levetiracetam (40 mg/kg/day i.p.) levetiracetam in combination with different doses of quercetin (10 mg/kg; 20 mg/kg; 40 mg/kg)/day/p.o. for 15 days. Except naïve, all the groups were challenged with pentylenetetrazole (35 mg/kg i.p.) on day 5, 10, and 15 to evaluate the seizure severity score. Depression was evaluated in all experimental groups using the tail suspension and sucrose preference test on days 1, 5, 10 and 15, 2 h after pentylenetetrazole challenge. Results suggested that vehicle treated kindled animals were significantly associated with depression. Chronic levetiracetam treatment significantly reduced seizure severity score, but further worsened the associated depression. Quercetin supplementation with levetiracetam dose dependently ameliorated depression associated with epilepsy. Neurochemical and biochemical findings also supported the behavioural findings of the study. Thus, our results suggested that supplementation of quercetin with levetiracetam could be explored further for combined treatment of epilepsy and comorbid depression.

The effects of quercetin on the gene expression of the GABAA receptor α5 subunit gene in a mouse model of kainic acid-induced seizure.

The flavonoid quercetin has recently been reported to have neuroprotective effects, and the role of the gamma-aminobutyric acid A alpha 5 subunit (GABAA α5) receptor has been determined in some nervous system disorders. The aim of this study was to identify the molecular mechanism of the effect of quercetin administered at anticonvulsive doses on the expression of the GABAA α5 receptor gene in kainic acid (KA)-induced seizures in mice. The experimental animals were divided into four groups: control, KA, and KA + quercetin at 50 or 100mg/kg, respectively. The results showed a dose-dependent reduction in the behavioral seizure score with quercetin pre-treatment in the KA mouse model. Two hours after the end of the 7-day treatment regimen, expression of the GABAA α5 receptor gene in the hippocampus was found to be increased in the KA group, but this increase was reduced in the KA + quercetin 50 or 100mg/kg treatment groups. These results suggest that expression of the GABAA α5 receptor could be a mechanism for reducing seizure severity or may be a marker of seizure severity. Further studies are necessary to clarify quercetin's mechanism of action and the relation of GABAA α5 receptor gene expression to seizure severity.

Adjuvant neuronal nitric oxide synthase inhibition for combined treatment of epilepsy and comorbid depression.

Elevated nitric oxide (NO) levels in the brain have been apparently associated with depression in kindled animals. Owing to the major role of neuronal nitric oxide synthase (nNOS) in brain and ineffectiveness of antiepileptic drugs (AEDs) in restoring nitrosative stress, the present study was envisaged to evaluate the adjuvant nNOS inhibitor, 7-nitroindazole (7-NI) with valproic acid for combined treatment of epilepsy and associated depression. Pentylenetetrazole kindled animals associated with depression were treated with vehicle, valproate (300mg/kg/day ip), valproate with 7-NI (10mg/kg; 20mg/kg; 40mg/kg)/day ip and 7-NI (40mg/kg/day ip) for 15days. Except naïve, all groups were challenged with pentylenetetrazole (35mg/kg ip) on days 5, 10, and 15 to evaluate seizure severity. Depression was evaluated in all experimental groups using the tail suspension and forced swim test on days 1, 5, 10 and 15. On day 15, biochemical (corticosterone levels) and neurochemical (serotonin, kynurenine, tryptophan, glutamate, GABA, nitrite levels) estimations were carried out in cortical and hippocampal area of mice brain. Vehicle treated kindled animals were significantly associated with depression. Chronic valproate treatment in kindled animals significantly reduced seizure severity, but could not reverse associated depression. 7-NI per se treatment in kindled animals was also reported unable to restore the associated depression completely. However, 7-NI supplementation with valproate significantly reduced seizure severity score and completely ameliorated depression with restoration of altered biochemical and neurochemical milieu. Adjuvant nNOS inhibition can be previewed as safe therapy with AEDs for the combined management of epilepsy and associated depression.

Quantifying antiepileptic drug effects using intrinsic excitability measures.

Pathologic increases in excitability levels of cortical tissue commonly underlie the initiation and spread of seizure activity in patients with epilepsy. By reducing the excitability levels in neural tissue, antiepileptic drug (AED) pharmacotherapy aims to reduce seizure severity and frequency. However, AEDs may also bring about adverse effects, which have been reported to increase with higher AED load. Measures that monitor the dose-dependent effects of AEDs on cortical tissue and quantify its excitability level are therefore of prime importance for efficient clinical care and treatment but have been difficult to identify. Here, we systematically analyze continuous multiday electrocorticography (ECoG) data from 10 patients under different levels of AED load and derive the recently proposed intrinsic excitability measures (IEMs) from different brain regions and across different frequency bands. We find that IEMs are significantly negatively correlated with AED load (prescribed daily dose/defined daily dose). Furthermore, we demonstrate that IEMs derived from different brain regions can robustly capture global changes in the degree of excitability. These results provide a step toward the ultimate goal of developing a reliable quantitative measure of central physiologic effects of AEDs in patients with epilepsy.

Evidence in support of using a neurochemistry approach to identify therapy for both epilepsy and associated depression.

The present study aimed to develop a neurochemistry-based single or adjuvant therapy approach for comprehensive management of epilepsy and associated depression employing pentylenetetrazole-kindled animals. Kindling was induced in two-month-old male Swiss albino mice by administering a subconvulsant pentylenetetrazole dose (35mg/kg, i.p.) at an interval of 48±2h. These kindled animals were treated with saline and sodium valproate (300mg/kg/day, i.p.) for 15days. Except for the naïve group, all other groups were challenged with pentylenetetrazole (35mg/kg, i.p.) on days 5, 10, and 15 to evaluate the seizure severity. Depression was evaluated in all experimental groups after normalization of locomotor activity, using tail suspension and forced swim test on days 1, 5, 10, and 15. Four hours after behavioral evaluations on day 15, all animals were euthanized to collect their serum and discrete brain parts. Corticosterone levels were estimated in all the experimental groups as a marker of a dysregulated hypothalamus pituitary adrenal axis. Neurochemical alterations (norepinephrine, dopamine, tryptophan, kynurenine, serotonin, glutamate, GABA, and total nitrate levels) were also estimated in the cortical and hippocampal areas of the mouse brain. Results revealed that saline-treated kindled animals were associated with significant depression and altered neurochemical milieu in comparison with naïve animals. Chronic valproate treatment in kindled animals significantly reduced seizure severity score bud did not ameliorate associated depression or completely restore altered biochemical and neurochemical milieu. Based on the observation of neurochemical changes in all the groups, we propose that restoration of altered neurochemical milieu, elevated indoleamine 2,3-dioxygenase enzyme activity, and corticosterone levels using pharmacological tools with/out valproic acid may be explored for management of both epilepsy and comorbid depression.

The Role of Gastrodin on Hippocampal Neurons after N-Methyl-D-Aspartate Excitotoxicity and Experimental Temporal Lobe Seizures.

Tian ma (Gastrodia elata, GE) is an ancient Chinese herbal medicine that has been suggested to be effective as an anticonvulsant and analgesic, and to have sedative effects against vertigo, general paralysis, epilepsy and tetanus. The primary active ingredient isolated from GE is termed gastrodin, which is the glucoside of 4-hydroxybenzyl alcohol (4-HBA). Gastrodin can abolish hypoxia-, glutamate- and N-methyl-D-aspartate (NMDA) receptor-induced toxicity in primary culture of rat cortical neurons, and reduces seizure severity in seizure-sensitive gerbils. We evaluated the effect of gastrodin on NMDA excitotoxicity in hippocampal slice cultures (HSCs) with propidium iodide (PI) fluorescence measurement. We also evaluated the effects of gastrodin for treating active in vivo temporal lobe seizures induced by lithium/pilocarpine. Seizure severity, time span to seizure onset, mortality rate and hippocampal histology for survivors were compared. The effect of gastrodin was evaluated for treating in vitro seizures induced by Mg²⁺-free medium in hippocampal slices. Frequencies and amplitudes of epileptiform discharges were compared. The effect of gastrodin on synaptic transmission was evaluated on hippocampal CA1 Schaffer collaterals. Application of 25 μM gastrodin significantly suppressed NMDA excitotoxicity in CA3 but not in CA1 hippocampus and dentate gyrus. Intraventricular gastrodin accelerated seizure onset for 12 min after intraperitoneal pilocarpine injection (P = 0.051). Three of five rats (60%) in the gastrodin group, and three of four (75%) in the dimethyl sulfoxide (DMSO) group died within 3 days after status epilepticus (SE). Gastrodin also failed to inhibit epileptiform discharges in hippocampal slices induced by Mg²⁺-free medium, believed to be NMDA receptor-mediated spontaneous activity. The frequencies of the spontaneous epileptiform discharges were similar under treatments with 25 μM gastrodin, 200 μM gastrodin and DMSO. For the evaluation of gastrodin on synaptic transmission, application of DMSO, 25 μM or 200 μM gastrodin had no significant effect on excitatory postsynaptic potential (EPSP) slopes. Gastrodin at 200 μM decreased paired-pulse facilitation (PPF) from 1.23 ± 0.04 to 1.12 ± 0.04 (P = 0.002). In conclusion, gastrodin failed to suppress in vivo and in vitro seizures in our study. Gastrodin showed no effect on hippocampal Schaffer collateral EPSP. These findings suggest that gastrodin does not interact with ionotropic glutamate receptors to inhibit NMDA receptor-facilitated seizures. However, gastrodin showed protective effects against NMDA toxicity on cultured hippocampal slices. Nevertheless, gastrodin is still a potential neuroprotective agent against NMDA excitotoxicity, with potential benefits for stroke and patients with epilepsy.

Involvement of the neuronal phosphotyrosine signal adaptor N-Shc in kainic acid-induced epileptiform activity.

BDNF-TrkB signaling is implicated in experimental seizures and epilepsy. However, the downstream signaling involved in the epileptiform activity caused by TrkB receptor activation is still unknown. The aim of the present study was to determine whether TrkB-mediated N-Shc signal transduction was involved in kainic acid (KA)-induced epileptiform activity. We investigated KA-induced behavioral seizures, epileptiform activities and neuronal cell loss in hippocampus between N-Shc deficient and control mice. There was a significant reduction in seizure severity and the frequency of epileptiform discharges in N-Shc deficient mice, as compared with wild-type and C57BL/6 mice. KA-induced neuronal cell loss in the CA3 of hippocampus was also inhibited in N-Shc deficient mice. This study demonstrates that the activation of N-Shc signaling pathway contributes to an acute KA-induced epileptiform activity and neuronal cell loss in the hippocampus. We propose that the N-Shc-mediated signaling pathway could provide a potential target for the novel therapeutic approaches of epilepsy.

Adjuvant indoleamine 2,3-dioxygenase enzyme inhibition for comprehensive management of epilepsy and comorbid depression

Epilepsy is one of the major neurological disorders frequently associated with psychiatric disorders such as depression. Alteration of tryptophan metabolism towards kynurenine pathway may be one of the plausible reasons for association of depression in epilepsy. Hence, this study was envisaged to evaluate the dose dependent inhibition of indoleamine 2,3-dioxygenase (IDO) enzyme (responsible for shifting tryptophan metabolism) employing minocycline with valproic acid for comprehensive management of epilepsy and comorbid depression. Kindling was induced in male swiss albino mice by administration of pentylenetetrazole subconvulsive dose (35mg/kg, i.p.) at an interval of 48±2h. Kindled animals were treated with saline, valproate (300mg/kg/day i.p.), valproate in combination with different doses of minocycline (10mg/kg; 20mg/kg; 40mg/kg)/day i.p. and minocycline per se (40mg/kg/day i.p.) for 15 days. Except naïve, all the groups were challenged with pentylenetetrazole (35mg/kg i.p.) on day 5, 10, and 15 to evaluate the seizure severity score. Depression was evaluated in all experimental groups using tail suspension and forced swim test on days 1, 5, 10 and 15, 2h after pentylenetetrazole challenge. Results suggested that saline treated kindled animals were significantly associated with depression. Chronic valproate treatment significantly reduced seizure severity score but unable to ameliorate the associated depression. Minocycline supplementation with valproic acid dose dependently ameliorated depression associated with epilepsy. Neurochemical and biochemical findings also supported the behavioural findings of the study. Thus, our results suggested that supplementation of IDO enzyme inhibitors with valproic acid could be explored further for comprehensive management of epilepsy and associated depression.

Saikosaponin a functions as anti-epileptic effect in pentylenetetrazol induced rats through inhibiting mTOR signaling pathway.

Saikosaponin a (SSa), which is one major bioactive compound isolated from radix bupleuri, has been demonstrated to exhibit the properties of anticonvulsant and antiepileptic in few reports. This study aims to clarify the molecular mechanism by which SSa protects against pentylenetetrazol (PTZ) induced epileptic seizure. PTZ induced rat and hippocampal neuron were established. Treated rats or hippocampal neuron with SSa, and mTOR, P70S6K, IL-1β and TNF-α were then determined. In PTZ induced rat, SSa significantly reduced seizure severity and duration while markedly elevated seizure latency, and it also down-regulated hippocampal p-mTOR, p-70S6K, L-1β and TNF-α expression. In hippocampal neurons exposed to PTZ, p-mTOR and p-70S6K expression levels were also decreased by SSa. Pre-incubated hippocampal neurons with leucine, an mTOR agonist, reversed the effects of SSa on decreasing cytokines expression and inhibiting cell apoptosis. The treatment of mTOR inhibitor rapamycin prevented against the increase of cytokines expression and hippocampal neuron apoptosis induced by PTZ. Leucine also canceled the alleviation of seizures and induction of hippocampal caspase-3 activity in PTZ induced rat with the treatment of SSa. SSa protects against PTZ induced epileptic seizure and hippocampal neuron apoptosis through inhibiting mTOR signaling pathway.

Eslicarbazepine Acetate Associated with Reduced Seizure Severity in Addition to Reduced Seizure Frequency (P2.031)

Eslicarbazepine Acetate Associated with Reduced Seizure Severity in Addition to Reduced Seizure Frequency (P2.031)

Lectin-mediated delivery of α-L-iduronidase: A novel approach for MPS I enzyme replacement therapy

Epilepsy with periodic and unpredictable seizures is associated with hippocampal glutamate toxicity and tissue reorganization. Astrocytes play an important role in mediating the neuroprotective effects of estradiol and reducing seizure severity. Accordingly, the protective effects of low and high doses of estradiol on behavioral, astrocytic involvement and neuronal survival aspects of Pilocarpine-induced epilepsy were investigated. Lithium- Pilocarpine (30 mg/kg) model was used to provoke epilepsy. Βeta-estradiol (2,40 μg/µl) was injected subcutaneously from 48 before to 48 h after seizure induction. Behavioral convulsions were then monitored and recorded on the day of induction. Four weeks later, glutamine synthetase (GS) activity and the astrocyte transporter GLT-1 expression of the hippocampus were measured. Moreover, hippocampal glutamate and GABA were evaluated to study excitability changes. Finally, neuronal counting in the hippocampus was also performed using Nissl staining. The latency for generalized clonic (GC) convulsions significantly increased while the rate of GC and death significantly reduced due to β-estradiol treatment. GS activity and GLT-1 expression increased in the groups receiving the high dose of β-estradiol and Pilocarpine. Furthermore, the amount of both GABA and glutamate content decreased due to high dose of estradiol, while only GABA increased in Pilocarpine treated rats. Finally, administration of β-estradiol with low and high doses increased and improved the density of nerve cells. It is concluded that chronic administration β-estradiol has anticonvulsant and neuroprotective properties which are plausibly linked to astrocytic activity.

Bromocriptine Mesylate Protects against Status Epilepticus and Temporal Lobe Epilepsy: Neurobehavioral, Histopathological and Neurochemical Evidences

Background: Dopamine (DA) plays a major role in the control of epileptic seizures arising in the limbic system, through D1/D2 receptor-mediated signaling. Objective: The study was intended to investigate whether bromocriptine mesylate (BRC), a dopamine (D2) receptor agonist, has an anti-seizure property, attenuates oxidative stress and neuronal morphological alterations against pilocarpine induced status epilepticus (SE) in mice, using sodium valproate (SVP) as comparator AED. Materials and Methods: SVP (300 mg/kg) and BRC (6 &10 mg/kg) were administered orally once daily for a period of 4 weeks followed by pilocarpine (300 mg/kg, i.p) to induce SE. The convulsions Original Research Article Pottoo et al.; INDJ, 6(4): 1-13, 2016; Article no.INDJ.24401 2 were monitored for 2 hrs post pilocarpine injection. At 2 hrs post pilocarpine injection hippocampal malondialdehyde, glutathione reduced, glutathione peroxidase, glutathione reductase and catalase activities were measured. While hippocampal histopathological assessment of neuronal injury was performed 24 hrs post pilocarpine injection. Results: We report that SVP (300 mg/kg) and BRC (6 &10 mg/kg) were able to reduce seizure severity score (P<0.001, P<0.01, P<0.05), attenuate oxidative damage in lipids and proteins, restore depletion in hippocampal glutathione reduced, glutathione peroxidase and glutathione reductase activities compared to toxic/pilocarpine control. Contrary catalase levels were strengthened as like pilocarpine control. In addition SVP (300 mg/kg) and BRC (6 & 10 mg/kg) protected against degeneration in hippocampal CA1, CA2, CA3 & DG regions (P<0.001, P<0.01, P<0.05) compared to pilocarpine control. Conclusions: The present study highlights the prominent dysregulation of dopaminergic system in seizures and perspectives for the development of novel therapeutic approaches acompassing dopaminergic drugs in amelioration of epileptic seizures especially status-epilepticus and temporal lobe epilepsy.

Intranasal delivery of obidoxime to the brain prevents mortality and CNS damage from organophosphate poisoning

Intranasal delivery is an emerging method for bypassing the blood brain barrier (BBB) and targeting therapeutics to the CNS. Oximes are used to counteract the effects of organophosphate poisoning, but they do not readily cross the BBB. Therefore, they cannot effectively counteract the central neuropathologies caused by cholinergic over-activation when administered peripherally. For these reasons we examined intranasal administration of oximes in an animal model of severe organophosphate poisoning to determine their effectiveness in reducing mortality and seizure-induced neuronal degeneration. Using the paraoxon model of organophosphate poisoning, we administered the standard treatment (intramuscular pralidoxime plus atropine sulphate) to all animals and then compared the effectiveness of intranasal application of obidoxime (OBD) to saline in the control groups. Intranasally administered OBD was effective in partially reducing paraoxon-induced acetylcholinesterase inhibition in the brain and substantially reduced seizure severity and duration. Further, intranasal OBD completely prevented mortality, which was 41% in the animals given standard treatment plus intranasal saline. Fluoro-Jade-B staining revealed extensive neuronal degeneration in the surviving saline-treated animals 24h after paraoxon administration, whereas no detectable degenerating neurons were observed in any of the animals given intranasal OBD 30min before or 5min after paraoxon administration. These findings demonstrate that intranasally administered oximes bypass the BBB more effectively than those administered peripherally and provide an effective method for protecting the brain from organophosphates. The addition of intranasally administered oximes to the current treatment regimen for organophosphate poisoning would improve efficacy, reducing both brain damage and mortality.

Reduced estradiol synthesis by letrozole, an aromatase inhibitor, is protective against development of pentylenetetrazole-induced kindling in mice

Neurosteroids, such as testosterone and their metabolites, are known to modulate neuronal excitability. The enzymes regulating the metabolism of these neurosteroids, thus, may be targeted as a noval strategy for the development of new antiepileptic drugs. The present work targeted two such enzymes i,e aromatase and 5α-reductase in order to explore the potential of letrozole (an aromatase inhibitor) on pentylenetetrazole (PTZ)-induced kindling in mice and the ability of finasteride (a 5α-reductase inhibitor) to modulate any such effects. PTZ (30 mg/kg, i.p.), when administered once every two days (for a total of 24 doses) induced kindling in Swiss albino mice. Letrozole (1 mg/kg, p.o.), administered prior to PTZ, significantly reduced the % incidence of kindling, delayed mean onset time of seizures and reduced seizure severity score. Letrozole reduced the levels of plasma 17β-estradiol after induction of kindling. The concurrent administration of finasteride and letrozole produced effects similar to letrozole on PTZ-kindling and on estradiol levels. This implies that the ability of letrozole to redirect the synthesis of dihydrotestosterone (DHT) and 5α-androstanediol from testosterone doesn't appear to play a significant role in the protective effects of letrozole against PTZ kindling. Letrozole, however, increased the levels of 5α-DHT in mice plasma. The aromatase inhibitors, thus, may be exploited for inhibiting the synthesis of proconvulsant (17β-estradiol) and/or redirecting the synthesis of anticonvulsant (DHT and 5α-androstanediol) neurosteroids.

The MCT-ketogenic diet as a treatment option in refractory childhood epilepsy: A prospective study with 2-year follow-up.

The present study assessed the long-term (i.e., 24months) efficacy of the ketogenic diet (KD) as an add-on therapy in children with refractory epilepsy, with focus on seizure frequency, seizure severity, and tolerability. Most patients were treated with the MCT-diet. At one and two years, 33% and 23%, respectively, of the 48 included patients were still on the KD. After three months, one year, and two years of treatment, 16.7% of the patients were responders. The highest responder rate (i.e., 22.9%) was seen at six and nine months of treatment. Of the fifteen patients with seizure clusters during baseline, 60% were responders after three months when looking at cluster reduction and most of them were not responders for the total seizure frequency. From three months of treatment onwards, most of the patients had a relevant decrease in seizure severity which was mainly related to the most severe seizure type. Gastrointestinal dysfunction was often reported, especially in the first six weeks of treatment. Growth deceleration was present in 30% of the patients, and weight reduction in 15%. Improved arousal was mentioned in 30% of patients. No patients developed ECG abnormalities or kidney stones. Increase in lipid profile was rare. The KD is an effective therapy for children with therapy-resistant epilepsy. Effectiveness is reflected in the reduction of seizure frequency as well as in the reduction of seizure severity. After 6months of treatment, it is obvious which patients are responders and tolerate the treatment well. Most of these patients will continue to benefit from the KD for a longer time. Long-term use of the diet was well tolerated.

Protective effect on phenytoin-induced cognition deficit in pentylenetetrazol kindled mice: A repertoire of Glycyrrhiza glabra flavonoid antioxidants

Context: Glycyrrhiza glabra L. (Febaceae) has been widely used in traditional medicine and scientifically explored for its anticonvulsant and memory improving potential.Objective: The objective of this study is to investigate the effect of flavonoid rich fraction of G. glabra root extract against phenytoin-induced cognition deficit in pentylenetetrazol (PTZ) kindled mice.Materials and methods: The ethyl acetate fraction was initially screened in different in vitro free radical scavenging assays. For in vivo studies, the kindled mice in different groups were given 15 d post-treatment with phenytoin (25 mg/kg; p.o.) per se or in combination with varying doses of the fraction (5, 10, and 15 mg/kg; p.o.). Seizure severity score and cognitive functions were accessed using Racine's scale and passive shock avoidance paradigm, respectively on every 5th d after a PTZ challenge dose (35 mg/kg; i.p.). At the end of study, the animals were scarified for cerebral biochemistry.Results: The fraction showed marked antioxidant activity indicated by low IC50 values in DPPH (20.9 µg/mL), nitric oxide radical scavenging (195.2 µg/mL), and capacity of hydrogen peroxide scavenging (3.4 µg/mL) assays. Treatment with phenytoin per se and along with the flavonoid rich fraction showed significant reduction in seizure severity score as compared to vehicle control. The combined-treated groups also showed improved cognitive functions indicated by reduced number of mistakes and increased step-down latency in passive shock avoidance paradigm.Conclusion: From the results, it can be concluded that the flavonoid rich fraction in combination with phenytoin reduces seizure severity and improve cognitive functions in PTZ-kindled mice.

Ethosuximide Reduces Mortality and Seizure Severity in Response to Pentylenetetrazole Treatment During Ethanol Withdrawal.

We recently demonstrated that T-type calcium channels are affected by alcohol abuse and withdrawal. Treatment with ethosuximide, an antiepileptic drug that blocks T-type calcium channels, reduces seizure activity induced by intermittent ethanol exposures and withdrawals. Here, we expand on these findings to test whether ethosuximide can reduce the sensitivity to pentylenetetrazole-induced seizures during ethanol withdrawal. We used an intermittent ethanol exposure model to produce withdrawal-induced hyperexcitability in DBA/2J mice. Ethosuximide (250 mg/kg) reduced seizure severity in mice undergoing ethanol withdrawal with concurrent PTZ treatment (20 mg/kg). Importantly, ethosuximide did not produce rebound excitability and protected against ethanol withdrawal-induced mortality produced by concurrent PTZ treatment (40 mg/kg). These results, in addition to previous preclinical findings, suggest that ethosuximide should be further evaluated as a safe, effective alternative to benzodiazepines for the treatment of alcohol withdrawal.

P2X purinoceptors as a link between hyperexcitability and neuroinflammation in status epilepticus.

There remains a need for more efficacious treatments for status epilepticus. Prolonged seizures result in the release of ATP from cells which activates the P2 class of ionotropic and metabotropic purinoceptors. The P2X receptors gate depolarizing sodium and calcium entry and are expressed by both neurons and glia throughout the brain, and a number of subtypes are upregulated after status epilepticus. Recent studies have explored the in vivo effects of targeting ATP-gated P2X receptors in preclinical models of status epilepticus, with particular focus on the P2X7 receptor (P2X7R). The P2X7R mediates microglial activation and the release of the proepileptogenic inflammatory cytokine interleukin 1β. The receptor may also directly modulate neurotransmission and gliotransmission and promote the recruitment of immune cells into brain parenchyma. Data from our group and collaborators show that status epilepticus produced by intraamygdala microinjection of kainic acid increases P2X7R expression in the hippocampus and neocortex of mice. Antagonism of the P2X7R in the model reduced seizure severity, microglial activation and interleukin 1β release, and neuronal injury. Coadministration of a P2X7R antagonist with a benzodiazepine also provided seizure suppression in a model of drug-refractory status epilepticus when either treatment alone was minimally effective. More recently, we showed that status epilepticus in immature rats is also reduced by P2X7R antagonism. Together, these findings suggest that P2X receptors may be novel targets for seizure control and interruption of neuroinflammation after status epilepticus. This article is part of a Special Issue entitled "Status Epilepticus".

Inhibition of the small GTPase Cdc42 in regulation of epileptic-seizure in rats

Altered expression of neuronal cytoskeletal proteins are known to play an important role in hyper-excitability of neurons in patients and animal models of epilepsy. Our previous work showed that cell division cycle 42 GTP-binding protein (Cdc42), a small GTPase of the Rho-subfamily, is significantly increased in the brain tissue of patients with temporal lobe epilepsy (TLE) and in the brain tissues of the epileptic model of rats. However, whether inhibition of Cdc42 can modify epileptic seizures has not been investigated. In this study, using a pilocarpine-induced epileptic model, we found that pretreatment with ML141, a specific inhibitor of Cdc42, reduces seizure severity. Whole-cell patch-clamp recording on CA1 pyramidal neurons in hippocampal slices from pilocarpine-induced epileptic model demonstrated that ML141 significantly inhibits the frequency of action potentials (APs), increases the amplitude and frequency of miniature inhibitory postsynaptic currents (mIPSCs), and increases the amplitude of evoked inhibitory postsynaptic currents (eIPSCs). However, ML141 did not have an impact on the miniature excitatory postsynaptic currents (mEPSCs). Our results are the first to indicate that Cdc42 plays an important role in the onset and progression of epileptic-seizures by regulating synaptic inhibition.

Neuroligin-1 Knockdown Suppresses Seizure Activity by Regulating Neuronal Hyperexcitability.

Abnormally synchronized synaptic transmission in the brain leads to epilepsy. Neuroligin-1 (NL1) is a synaptic cell adhesion molecule localized at excitatory synapses. NL1 modulates synaptic transmission and determines the properties of neuronal networks in the mammalian central nervous system. We showed that the expression of NL1 and its binding partner neurexin-1β was increased in temporal lobe epileptic foci in patients and lithium-pilocarpine-treated epileptic rats. We investigated electrophysiological and behavioral changes in epileptic rats after lentivirally mediated NL1 knockdown in the hippocampus to determine whether NL1 suppression prevented seizures and, if so, to explore the probable underlying mechanisms. Our behavioral studies revealed that NL1 knockdown in epileptic rats reduced seizure severity and increased seizure latency. Whole-cell patch-clamp recordings of CA1 pyramidal neurons in hippocampal slices from NL1 knockdown epileptic rats revealed a decrease in spontaneous action potential frequency and a decrease in miniature excitatory postsynaptic current (mEPSC) frequency but not amplitude. The amplitude of N-methyl-D-aspartate receptor (NMDAR)-dependent EPSCs was also selectively decreased. Notably, NL1 knockdown reduced total NMDAR1 expression and the surface/total ratio in the hippocampus of epileptic rats. Taken together, these data indicate that NL1 knockdown in epileptic rats may reduce the frequency and severity of seizures and suppress neuronal hyperexcitability via changes in postsynaptic NMDARs.