Capsaicin prevents kainic acid-induced epileptogenesis in mice

Epilepsy is a neurodegenerative disease with periodic occurrences of spontaneous seizures as the main symptom. The aim of this study was to investigate the neuroprotective effects of capsaicin, the major ingredient of hot peppers, in a kainic acid (KA)-induced status epilepticus model. After intraperitoneal injections of KA (30mg/kg) in 8-week-old male ICR mice, the animals were treated subcutaneously with capsaicin (0.33mg/kg or 1mg/kg) and then examined for any anti-ictogenic, hypothermic, antioxidative, anti-inflammatory, and anti-apoptotic effects of the capsaicin treatment 3 days after KA treatment. KA injections significantly enhanced neurodegenerative conditions but co-injection with capsaicin reduced the detrimental effects of KA in a dose-dependent manner in mice. The co-administered group that received KA and 1mg/kg of capsaicin showed significantly decreased behavioral seizure activity and body temperature for 3h and also remarkably blocked intense and high-frequency seizure discharges in the parietal cortex for 3 days compared with those that received KA alone. Capsaicin treatment significantly diminished the levels of oxidant activity and malondialdehyde concentration and increased the antioxidant activity in the blood and brain of KA-treated mice. In addition, capsaicin significantly lowered the KA-induced increase in the concentration of the cytokines IL-1β and TNF-α in the brain. Furthermore, co-treatment of KA and capsaicin (1mg/kg) resulted in considerably decreased apoptotic cell death in the cornu ammonis sections of the hippocampus compared with that seen in the KA-alone group. These findings indicate that capsaicin is preventative for the epileptogenesis induced by KA in mice.     

Uncaria rhynchophylla and rhynchophylline improved kainic acid-induced epileptic seizures via IL-1β and brain-derived neurotrophic factor

Uncaria rhynchophylla (UR) has been used for the treatment of convulsions and epilepsy in traditional Chinese medicine. This study reported the major anti-convulsive signaling pathways and effective targets of UR and rhynchophylline (RP) using genomic and immunohistochemical studies. Epileptic seizure model was established by intraperitoneal injection of kainic acid (KA) in rats. Electroencephalogram and electromyogram recordings indicated that UR and RP improved KA-induced epileptic seizures. Toll-like receptor (TLR) and neurotrophin signaling pathways were regulated by UR in both cortex and hippocampus of KA-treated rats. KA upregulated the expression levels of interleukin-1β (IL-1β) and brain-derived neurotrophin factor (BDNF), which were involved in TLR and neurotrophin signaling pathways, respectively. However, UR and RP downregulated the KA-induced IL-1β and BDNF gene expressions. Our findings suggested that UR and RP exhibited anti-convulsive effects in KA-induced rats via the regulation of TLR and neurotrophin signaling pathways, and the subsequent inhibition of IL-1β and BDNF gene expressions.     

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.     

美满霉素对癫痫大鼠海马神经元凋亡的影响

目的探讨美满霉素(minocycline,MC)对癫痫模型大鼠海马神经元的抗凋亡保护作用。方法将大鼠随机分为3组:生理盐水对照组(NS组),海人酸致痫组(KA组)和美满霉素预处理+海人酸组(MC+KA组)。以免疫组化法检测各组大鼠造模后2h、8h和24h海马部位Cytochrome C(CytC)免疫反应性。采用半定量RT-PCR和免疫组化法检测24h、48h caspase-3 mRNA和caspase-3表达情况。结果在KA致痫后2hCytC即开始有表达,8h达到高峰,24h表达减少,而MC预处理明显减弱此效应。caspase-3 mRNA的含量及caspase-3免疫反应性在24h时间点三组之间无明显差异,在48h时间点,KA组明显高于对照组(P0.05),MC预处理则明显拮抗KA诱导的caspase-3高表达。结论 KA致痫能诱导大鼠海马神经元凋亡,而MC能通过抑制凋亡途径对海马神经元发挥神经保护作用。     

Loss of p53 results in protracted electrographic seizures and development of an aggravated epileptic phenotype following status epilepticus

The p53 tumor suppressor is a multifunctional protein, which regulates cell cycle, differentiation, DNA repair and apoptosis. Experimental seizures up-regulate p53 in the brain, and acute seizure-induced neuronal death can be reduced by genetic deletion or pharmacologic inhibition of p53. However, few long-term functional consequences of p53 deficiency have been explored. Here, we investigated the development of epilepsy triggered by status epilepticus in wild-type and p53-deficient mice. Analysis of electroencephalogram (EEG) recordings during status epilepticus induced by intra-amygdala kainic acid (KA) showed that seizures lasted significantly longer in p53-deficient mice compared with wild-type animals. Nevertheless, neuronal death in the hippocampal CA3 subfield and the neocortex was significantly reduced at 72 h in p53-deficient mice. Long-term continuous EEG telemetry recordings after status epilepticus determined that the sum duration of spontaneous seizures was significantly longer in p53-deficient compared with wild-type mice. Hippocampal damage and neuropeptide Y distribution at the end of chronic recordings was found to be similar between p53-deficient and wild-type mice. The present study identifies protracted KA-induced electrographic status as a novel outcome of p53 deficiency and shows that the absence of p53 leads to an exacerbated epileptic phenotype. Accordingly, targeting p53 to protect against status epilepticus or related neurologic insults may be offset by deleterious consequences of reduced p53 function during epileptogenesis or in chronic epilepsy.     

Antioxidant, Anticonvulsive and Neuroprotective Effects of Dapsone and Phenobarbital Against Kainic Acid-Induced Damage in Rats

Excitotoxicity due to glutamate receptors (GluRs) overactivation is a leading mechanism of oxidative damage and neuronal death in various diseases. We have shown that dapsone (DDS) was able to reduce both neurotoxicity and seizures associated to the administration of kainic acid (KA), an agonist acting on AMPA/KA receptors (GluK1–GluK5). Recently, it has been shown that phenobarbital (PB) is also able to reduce epileptic activity evoked by that receptor. In the present study, we tested the antioxidative, anticonvulsive and neuroprotective effects of DDS and PB administered alone or in combination upon KA toxicity to rats. Results showed that KA increased lipid peroxidation and diminished reduced glutathione (GSH), 24 h after KA administration and both drugs in combination or individually inhibited these events. Likewise, KA promotes mortality and this event was antagonized by effect of both treatments. Additionally, the behavioral evaluation showed that DDS and PB administered alone or in combination decreased the number of limbic seizures and reduced the percentage of animals showing tonic–clonic seizures versus the control group, which was administered only with KA. Finally, our study demonstrated that all of the treatments prevented the neuronal death of the pyramidal cell layer of hippocampal CA-3. In conclusion, the treatment with DDS and PB administrated alone or in combination exerted antioxidant, anticonvulsive and neuroprotective effects against the neurotoxicity induced by KA in rats, but their effects were not additive. Thus, it may be good options of treatment in diseases such as epilepsy and status epilepicus, administered separately.     

局部高频电刺激海马对海人酸致痫大鼠海马细胞外谷氨酸和γ-氨基丁酸释放的影响

目的：通过高频电刺激海人酸癫痫模型大鼠海马,观察海马细胞外谷氨酸（Glu）和γ-氨基丁酸（GABA）的动态变化。方法：将SD大鼠分成4大组（n=10）：①空白组;②海人酸组;③假刺激组：植入刺激电极未予电刺激;④电刺激组：海人酸注射后予130 Hz电刺激。利用微透析技术收集不同时段海马细胞外液,应用高效液相-荧光检测法测定收集液Glu、GABA的浓度。结果：注射海人酸后Glu明显升高,并持续至第14天,电刺激使Glu明显下降;而注射海人酸后GABA呈短暂性升高,后逐渐下降于第4天后保持稍高于正常水平,电刺激并无明显改变GABA的水平。结论：海马细胞外Glu下降在海马电刺激治疗癫痫中起到重要作用;高频电刺激海马选择性地减少谷氨酸能神经元活动,但不影响GABA的释放。     

Prevention of kainic acid-induced changes in nitric oxide level and neuronal cell damage in the rat hippocampus by manganese complexes of curcumin and diacetylcurcumin

Curcumin is a natural antioxidant isolated from the medicinal plant Curcuma longa Linn. We previously reported that manganese complexes of curcumin (Cp-Mn) and diacetylcurcumin (DiAc-Cp-Mn) exhibited potent superoxide dismutase (SOD)-like activity in an in vitro assay. Nitric oxide (NO) is a free radial playing a multifaceted role in the brain and its excessive production is known to induce neurotoxicity. Here, we examined the in vivo effect of Cp-Mn and DiAc-Cp-Mn on NO levels enhanced by kainic acid (KA) and L-arginine (L-Arg) in the hippocampi of awake rats using a microdialysis technique. Injection of KA (10 mg/kg, i.p.) and L-Arg (1000 mg/kg, i.p.) significantly increased the concentration of NO and Cp-Mn and DiAc-Cp-Mn (50 mg/kg, i.p.) significantly reversed the effects of KA and L-Arg without affecting the basal NO concentration. Following KA-induced seizures, severe neuronal cell damage was observed in the CA1 and CA3 subfields of hippocampal 3 days after KA administration. Pretreatment with Cp-Mn and DiAc-Cp-Mn (50 mg/kg, i.p.) significantly attenuated KA-induced neuronal cell death in both CA1 and CA3 regions of rat hippocampus compared with vehicle control, and Cp-Mn and DiAc-Cp-Mn showed more potent neuroprotective effect than their parent compounds, curcumin and diacetylcurcumin. These results suggest that Cp-Mn and DiAc-Cp-Mn protect against KA-induced neuronal cell death by suppression of KA-induced increase in NO levels probably by their NO scavenging activity and antioxidative activity. Cp-Mn and DiAc-Cp-Mn have an advantage to be neuroprotective agents in the treatment of acute brain pathologies associated with NO-induced neurotoxicity and oxidative stress-induced neuronal damage such as epilepsy, stroke and traumatic brain injury.     

Anti-epileptic effect of the new calcium channel blocker IOS-1.1212]

In experiments on freely moving male Wistar rats it was shown that IOS-1.1212 (1,4-dihydropyridine) in a dose 2 and 10 mg/kg (i. p.) suppressed the penicillin-induced focal epileptic activity in cerebral cortex. Similar suppressing effect of IOS-1.1212 was shown on acute generalized tonic-clonic pentylenetetrazol (PTZ) seizures (75 mg/kg i. p.) and on chronic PTZ administration (PTZ-kindling, 30 mg/kg i. p. during 30 days): when injected 30 min before each PTZ administration it delayed the development of kindling-induced seizures susceptibility in randomized animals (series 1) and attenuated the severity of seizures in PTZ-sensitive animals (series 2). However, IOS-1.1212 had no effect on the strychnine-induced focal epileptic activity. In male Icr:Icl mice IOS-1.1212 in a dose 1.5 and 5 mg/kg also influenced the PTZ convulsions (i. v. titration of 1% solution at a rate of 0.01 ml/s) and had no effect on the strychnine convulsions (i. v. titration of 0.01% solution at a rate of 0.01 ml/s) and on maximal electroshock. In addition, IOS-1.1212 significantly increased antiepileptic effect of phenobarbital on maximal electroshock.     

Kainate-induced mitochondrial oxidative stress contributes to hippocampal degeneration in senescence-accelerated mice

We have demonstrated that kainate (KA) induces a reduction in mitochondrial Mn-superoxide dismutase (Mn-SOD) expression in the rat hippocampus and that KA-induced oxidative damage is more prominent in senile-prone (SAM-P8) than senile-resistant (SAM-R1) mice. To extend this, we examined whether KA seizure sensitivity contributed to mitochondrial degeneration in these mouse strains. KA-induced seizure susceptibility in SAM-P8 mice paralleled prominent increases in lipid peroxidation and protein oxidation and was accompanied by significant impairment in glutathione homeostasis in the hippocampus. These findings were more pronounced in the mitochondrial fraction than in the hippocampal homogenate. Consistently, KA-induced decreases in Mn-SOD protein expression, mitochondrial transmembrane potential, and uncoupling protein (UCP)-2 expression were more prominent in SAM-P8 than SAM-R1 mice. Marked release of cytochrome c from mitochondria into the cytosol and a higher level of caspase-3 cleavage were observed in KA-treated SAM-P8 mice. Additionally, electron microscopic evaluation indicated that KA-induced increases in mitochondrial damage and lipofuscin-like substances were more pronounced in SAM-P8 than SAM-R1 animals. These results suggest that KA-mediated mitochondrial oxidative stress contributed to hippocampal degeneration in the senile-prone mouse.     

Choline acetyltransferase, glutamic acid decarboxylase and somatostatin in the kainic acid model for chronic temporal lobe epilepsy

The aim of the study was to investigate neurochemical changes in a kainic acid (KA; 10 mg/kg, s.c.)-induced spontaneous recurrent seizure model of epilepsy, 6 months after the initial KA-induced seizures. The neuronal markers of cholinergic and gamma-aminobutyric acid (GABA)ergic systems, i.e. choline acetyltransferase (ChAT) and glutamic acid decarboxylase (GAD) activities, and a marker for neuropeptide, i.e. level of somatostatin, have been investigated. The brain regions investigated were the hippocampus, amygdala/piriform cortex, caudate nucleus, substantia nigra and the frontal, parietal, temporal and occipital cortices. Six months after KA injection, reduced ChAT activity was observed in the amygdala/piriform cortex (47% of control; p<0.001), increased ChAT activity in the hippocampus (119% of control; p<0.01) and normal ChAT activity in the other brain regions. The activity of GAD was significantly increased in all analysed cortical regions (between 146 and 171% of control), in the caudate nucleus (144% of control; p<0.01) and in the substantia nigra (126% of control; p<0.01), whereas in the amygdala/piriform cortex, the GAD activity was moderately lowered. The somatostatin level was significantly increased in all cortical regions (between 162 and 221% of control) as well as in the hippocampus (119% of control), but reduced in the amygdala/piriform cortex (45% of control; p<0.01). Six months after KA injection, the somatostatin:GAD ratio was lowered in the amygdala/piriform cortex (49% of control) and in the caudate nucleus (41% of control), whereas it was normal in the hippocampus and moderately increased in the cortical brain regions. A positive correlation was found between seizure severity and the reduction of both ChAT activities and somatostatin levels in the amygdala/piriform cortex. The results show a specific pattern of changes for cholinergic, GABAergic and somatostatinergic activities in the chronic KA model for epilepsy. The revealed data suggest a functional role for them in the new network that follows spontaneous repetitive seizures.     

Anticonvulsive and free radical scavenging actions of two herbs, Uncaria rhynchophylla (MIQ) Jack and Gastrodia elata Bl., in kainic acid-treated rats

Uncaria rhynchophylla (Miq.) Jack (UR) and Gastrodia elata BI. (GE) are traditional Chinese herbs that are usually used in combination to treat convulsive disorders, such as epilepsy, in China. The aim of this study was to compare the anticonvulsive and free radical scavenging activities of UR alone and UR in combination with GE in rats. For the in vitro studies, brain tissues from 6 male Sprague-Dawley (SD) rats were treated with 120 microg/ml kainic acid (KA), with or without varied concentrations of UR or UR plus GE. For the in vivo studies, male SD rats (6 per group) received intraperitoneal (i.p.) injection of KA 12 mg/kg to induce epileptic seizures and generation of free radicals, with or without oral administration of UR 1 g/kg alone or UR 1 g/kg plus GE 1 g/kg. Epileptic seizures were verified by behavioral observations, and electroencephalography (EEG) and electromyography (EMG) recordings. These results showed that UR alone decreased KA-induced lipid peroxide levels in vitro, whereas UR plus GE did not produce a greater effect than UR alone. UR significantly reduced counts of wet dog shakes (WDS), paw tremor (PT) and facial myoclonia (FM) in KA-treated rats and significantly delayed the onset time of WDS, from 27 min in the control group to 40 min in the UR group. UR plus GE did not inhibit seizures more effectively than UR alone, but did further prolong the onset time of WDS to 63 min (P < 0.05 vs. UR alone). UR alone reduced the levels of free radicals in vivo, as measured by lipid peroxidation in the brain and luminol-chemiluminescence (CL) counts and lucigenin-CL counts in the peripheral whole blood, but the combination of GE and UR did not reduce free radical levels more markedly than UR alone. In conclusion, our results indicate that UR has anticonvulsive and free radical scavenging activities, and UR combined with GE exhibit greater inhibition on the onset time of WDS than UR alone. These findings suggest that the anticonvulsive effects of UR and GE may be synergistic. However, the mechanism of interaction between UR and GE remains unknown.     

Proteolytic fragments of laminin promote excitotoxic neurodegeneration by up-regulation of the KA1 subunit of the kainate receptor

Degradation of the extracellular matrix (ECM) protein laminin contributes to excitotoxic cell death in the hippocampus, but the mechanism of this effect is unknown. To study this process, we disrupted laminin γ1 (lamγ1) expression in the hippocampus. Lamγ1 knockout (KO) and control mice had similar basal expression of kainate (KA) receptors, but the lamγ1 KO mice were resistant to KA-induced neuronal death. After KA injection, KA1 subunit levels increased in control mice but were unchanged in lamγ1 KO mice. KA1 levels in tissue plasminogen activator (tPA)–KO mice were also unchanged after KA, indicating that both tPA and laminin were necessary for KA1 up-regulation after KA injection. Infusion of plasmin-digested laminin-1 into the hippocampus of lamγ1 or tPA KO mice restored KA1 up-regulation and KA-induced neuronal degeneration. Interfering with KA1 function with a specific anti-KA1 antibody protected against KA-induced neuronal death both in vitro and in vivo. These results demonstrate a novel pathway for neurodegeneration involving proteolysis of the ECM and KA1 KA receptor subunit up-regulation.     

Epileptogenesis following Kainic Acid-Induced Status Epilepticus in Cyclin D2 Knock-Out Mice with Diminished Adult Neurogenesis

The goal of this study was to determine whether a substantial decrease in adult neurogenesis influences epileptogenesis evoked by the intra-amygdala injection of kainic acid (KA). Cyclin D2 knockout (cD2 KO) mice, which lack adult neurogenesis almost entirely, were used as a model. First, we examined whether status epilepticus (SE) evoked by an intra-amygdala injection of KA induces cell proliferation in cD2 KO mice. On the day after SE, we injected BrdU into mice for 5 days and evaluated the number of DCX- and DCX/BrdU-immunopositive cells 3 days later. In cD2 KO control animals, only a small number of DCX+ cells was observed. The number of DCX+ and DCX/BrdU+ cells/mm of subgranular layer in cD2 KO mice increased significantly following SE (p<0.05). However, the number of newly born cells was very low and was significantly lower than in KA-treated wild type (wt) mice. To evaluate the impact of diminished neurogenesis on epileptogenesis and early epilepsy, we performed video-EEG monitoring of wt and cD2 KO mice for 16 days following SE. The number of animals with seizures did not differ between wt (11 out of 15) and cD2 KO (9 out of 12) mice. The median latency to the first spontaneous seizure was 4 days (range 2 – 10 days) in wt mice and 8 days (range 2 – 16 days) in cD2 KO mice and did not differ significantly between groups. Similarly, no differences were observed in median seizure frequency (wt: 1.23, range 0.1 – 3.4; cD2 KO: 0.57, range 0.1 – 2.0 seizures/day) or median seizure duration (wt: 51 s, range 23 – 103; cD2 KO: 51 s, range 23 – 103). Our results indicate that SE-induced epileptogenesis is not disrupted in mice with markedly reduced adult neurogenesis. However, we cannot exclude the contribution of reduced neurogenesis to the chronic epileptic state.     

Anticonvulsant properties of the cerebrospinal fluid during activation of the antiepileptic system of the brain

Cerebrospinal fluid (CSF) was obtained after 30-40 sessions of daily electrical stimulation of the cat cerebellum vermis. The intraventricular injection of CSF (10 microliters) to Wistar rats increased the latent period of initial seizure manifestations, significantly reduced the number of animals with seizures and reduced the severity of seizures induced by korazol injection (40 mg/kg). Analogous seizure changes were observed in rats after intraventricular injection of CSF (10 microliters) from cats subject to 3-10 electroshock seizure fits. Intraventricular injection of CSF (250 microliters) obtained from cats after electroshock to cats with strychnine-induced epileptic foci in the brain cortex led to the suppression of the epileptic activity. The conclusion was made that different ways of antiepileptic system activation cause the accumulation of endogenous antiepileptic substances in CSF.     

MST3在颞叶癫痫模型小鼠海马的表达变化

目的观察海人酸(kainic acid,KA)所致癫痫(epilepsy,EP)小鼠海马Ste20蛋白激酵素(MST3)表达水平的变化,探讨MST3在癫痫发病过程中的可能作用。方法选用成年雄性小鼠,并随机分成模型组和对照组。模型组小鼠侧脑室注射2μL(100 ng/μL)KA,分别于术后3、8、24 h收集动物标本以进行检测。使用RT-PCR和Western Blot测定MST3 mRNA含量和MST3蛋白动态表达变化,应用免疫组化观察MST3在海马的表达分布与特点。结果与正常对照组相比,模型组海马组织内MST3mRNA的表达随时间持续升高,24 h达到高峰;MST3的蛋白表达也表现出同样的动态升高趋势;术后3～24 h的模型组海马免疫组化检测显示,模型组MST3主要以海马齿状回、门回区、CA3区域表达增加为主,并且这些区域表达逐渐递增。结论随着时间的推移,MST3表达水平呈现逐渐增加趋势,可能与神经元损伤造成的凋亡之间有密切的关系,提示MST3可能在癫痫发病过程中起重要作用。     

Retigabine,a Kv7.2/Kv7.3-Channel Opener,Attenuates Drug-Induced Seizures in Knock-In Mice Harboring Kcnq2 Mutations

The hetero-tetrameric voltage-gated potassium channel K_v7.2/K_v7.3, which is encoded by KCNQ2 and KCNQ3, plays an important role in limiting network excitability in the neonatal brain. K_v7.2/K_v7.3 dysfunction resulting from KCNQ2 mutations predominantly causes self-limited or benign epilepsy in neonates, but also causes early onset epileptic encephalopathy. Retigabine (RTG), a K_v7.2/ K_v7.3-channel opener, seems to be a rational antiepileptic drug for epilepsies caused by KCNQ2 mutations. We therefore evaluated the effects of RTG on seizures in two strains of knock-in mice harboring different Kcnq2 mutations, in comparison to the effects of phenobarbital (PB), which is the first-line antiepileptic drug for seizures in neonates. The subjects were heterozygous knock-in mice (Kcnq2^Y284C/+ and Kcnq2^A306T/+) bearing the Y284C or A306T Kcnq2 mutation, respectively, and their wild-type (WT) littermates, at 63–100 days of age. Seizures induced by intraperitoneal injection of kainic acid (KA, 12mg/kg) were recorded using a video-electroencephalography (EEG) monitoring system. Effects of RTG on KA-induced seizures of both strains of knock-in mice were assessed using seizure scores from a modified Racine’s scale and compared with those of PB. The number and total duration of spike bursts on EEG and behaviors monitored by video recording were also used to evaluate the effects of RTG and PB. Both Kcnq2^Y284C/+ and Kcnq2^A306T/+ mice showed significantly more KA-induced seizures than WT mice. RTG significantly attenuated KA-induced seizure activities in both Kcnq2^Y284C/+ and Kcnq2^A306T/+ mice, and more markedly than PB. This is the first reported evidence of RTG ameliorating KA-induced seizures in knock-in mice bearing mutations of Kcnq2, with more marked effects than those observed with PB. RTG or other K_v7.2-channel openers may be considered as first-line antiepileptic treatments for epilepsies resulting from KCNQ2 mutations.     

Impact of Corticosterone Treatment on Spontaneous Seizure Frequency and Epileptiform Activity in Mice with Chronic Epilepsy

Stress is the most commonly reported precipitating factor for seizures in patients with epilepsy. Despite compelling anecdotal evidence for stress-induced seizures, animal models of the phenomena are sparse and possible mechanisms are unclear. Here, we tested the hypothesis that increased levels of the stress-associated hormone corticosterone (CORT) would increase epileptiform activity and spontaneous seizure frequency in mice rendered epileptic following pilocarpine-induced status epilepticus. We monitored video-EEG activity in pilocarpine-treated mice 24/7 for a period of four or more weeks, during which animals were serially treated with CORT or vehicle. CORT increased the frequency and duration of epileptiform events within the first 24 hours of treatment, and this effect persisted for up to two weeks following termination of CORT injections. Interestingly, vehicle injection produced a transient spike in CORT levels – presumably due to the stress of injection – and a modest but significant increase in epileptiform activity. Neither CORT nor vehicle treatment significantly altered seizure frequency; although a small subset of animals did appear responsive. Taken together, our findings indicate that treatment of epileptic animals with exogenous CORT designed to mimic chronic stress can induce a persistent increase in interictal epileptiform activity.     

海马mu型阿片肽受体介导大鼠癫痫发作敏感性形成

为探讨海马mu型阿片肽受体介导癫痫发作敏感性形成的作用,实验采用微渗透泵技术,观察大鼠腹侧海马注射mu型阿片肽受体激动剂PL017(2.09、2.59、3.29μg/μ1)、拮抗剂β-funaltrexamine hydrochloride(β-FNA、0.88、1.10、1.35μg/μl)对红藻氨酸(kainic acid,KA)诱导癫痫发作的干预作用.PL017能够明显缩短癫痫发作潜伏期、增加癫痫发作级别(P＜0.05),β-FNA则可显著延长癫痫发作潜伏期、降低发作级别(P＜0.01);PL017和β-FNA的干预作用均表现出剂量依赖效应.结果表明,海马mu型阿片肽受体具有促进KA诱导的癫痫发作敏感性形成作用.     

Antiepileptic effects of nifedipine]

In experiments on freely moving male Wistar rats it was shown that nifedipine in a dose 10 mg/kg (i.p.) suppressed the penicillin-induced focal epileptic activity in cerebral cortex. A similar suppressing effect of nifedipine was shown on acute generalized tonic-clonic pentylenetetrazol (PTZ) seizures (75 mg/kg, i.p.). Nifedipine in the same dose was not effective on chronic PTZ administration (PTZ-kindling, 30 mg/kg i.p. during 28 days): when injected 30 min before each PTZ administration it didn't delay the development of kindling induced seizure susceptibility and had no effect on the severity of seizures. The administration of nifedipine in a dose of 10 or 30 mg/kg to control kindled animals which had not been treated with nifedipine had no influence on the severity of seizures provoked by a testing dose of PTZ (30 mg/kg i.p.): its intensity was similar to that of caused by PTZ injection along.