托吡酯对癫痫大鼠海马细胞外液氨基酸和神经元凋亡的影响

目的研究托吡酯对癫癎大鼠海马区细胞外液氨基酸和神经元凋亡的影响.方法采用戊四氮(PTZ)致癎模型,大鼠癫癎发作后连续给予托吡酯(TPM)80 mg·kg-1·d-1和卡马西平40 mg·kg-1·d-1,共14 d.以TUNEL方法标记DNA片段,原位检测海马凋亡的神经细胞.脑内微透析技术采集大鼠海马细胞外液,反相高效液相色谱技术测定氨基酸类神经递质的含量.结果TPM组、卡马西平组与对照组比较,凋亡细胞数存在显著差异(P＜0.001),TPM组与卡马西平组相比无显著差异(P＞0.05).TPM可明显升高海马细胞外液γ-氨基丁酸(GABA)水平,并降低谷氨酸(Glu)浓度.结论TPM可减轻大鼠癫癎发作后的神经元损伤,这种作用可能是氨基酸变化的结果;但在我们的实验中,没有发现TPM对癫癎后脑损伤比卡马西平有更明显的神经保护作用.     

戊四氮点燃癫癎大鼠空间学习记忆改变及海马NR2B表达

目的观察戊四氮点燃癫癎大鼠空间学习记忆功能变化及海马NMDA2型受体(NR2)B亚单位(NR2B)表达,探讨二者的关系及PTZ致癎大鼠认知障碍发生的分子机制。方法采用戊四氮(PTZ)慢性癫癎(CE)模型,Y-迷宫对两组大鼠进行行为学检测,免疫组织化学方法观察两组大鼠海马CA3区NR2B表达的变化,反转录多聚酶链反应(RT-PCR)方法检测大鼠海马NR2B mRNA的表达。结果癫癎组大鼠空间学习记忆能力受损;其海马CA3区NR2B阳性细胞较对照组明显减少(P<0.01),同时伴有海马NR2B mRNA表达下降(P<0.01)。结论戊四氮点燃癫癎大鼠空间学习记忆受损可能与海马神经元NR2B的表达减少有关。     

拉莫三嗪及丙戊酸钠对锂-匹罗卡品致(癎)大鼠的神经保护作用及其对癫(癎)的治疗作用

目的:观察拉莫三嗪(LTG)及丙戊酸钠(VPA)对锂-匹罗卡品癫(癎)持续状态(SE)大鼠海马锥体细胞、齿状回门区神经元的保护作用及对癫(癎)的治疗作用.方法:用大鼠制作锂-匹罗卡品SE动物模型,分三组:SE对照组,LTG治疗组和VPA治疗组.此三组在SE后2h给予安定阻断(癎)性发作,再分别给予适量生理盐水(NS)、...     

胍丁胺对戊四氮诱导慢性癫癎大鼠的保护作用和海马星形胶质细胞表达的影响

目的:探讨不同剂量胍丁胺对戊四氮诱导的慢性癫癎大鼠模型的保护作用及对海马区星形胶质细胞表达的影响。方法:连续28 d腹腔注射戊四氮35 mg.kg-1建立大鼠慢性癫癎模型。不同剂量胍丁胺(20、40、80 mg.kg-1)进行干预。观察大鼠癫癎发作行为学及海马的形态学变化,检测海马星形胶质细胞的表达。结果:胍丁胺40、80 mg.kg-1可降低癫癎发作的日均等级评分,减少海马神经元丢失及星形胶质细胞增生。结论:胍丁胺40、80 mg.kg-1可抑制慢性癫癎大鼠发作,降低惊厥发作后海马星形胶质细胞的异常增生及神经元损伤。     

甘珀酸对癫痫大鼠前脑connexin-32和GFAP表达研究

目的研究大鼠在脑室埋管注射甘珀酸(CBX)预处理后戊四氮导致癫痫发作时前脑内胶质纤维酸性蛋白(GFAP)和连接蛋白-32(Cx32)表达及其相互关系. 方法动物分为生理盐水(NS)对照组(NS组)、CBX预处理对照组(CBX组)、戊四氮(PTZ)致痫组(PTZ组)、CBX预处理后再PTZ致痫组(CBX PTZ组),应用免疫荧光组织化学双重标记显示GFAP和Cx32在前脑的表达及其相互关系.结果 CBX PTZ组的大鼠癫痫发作的行为表现比PTZ组显著加重,星形胶质细胞GFAP的表达也比PTZ组明显升高,值得注意的是CBX组的星形胶质细胞GFAP的表达比NS组明显升高.Cx32在PTZ引起的癫痫大鼠的大脑皮层、海马和杏仁核内是增加的,而CBX预处理后的癫痫模型中Cx32却降低了.在Cx32与GFAP双标的切片上发现,Cx32与GFAP阳性的星形胶质细胞非常接近,在CBX预处理后的癫痫模型中GFAP阳性的星形胶质细胞显著增加的同时Cx32却明显降低. 结论在整体动物CBX预处理可以导致癫痫发作增强,这可能与星形胶质细胞增生及其Cx32表达降低有关.     

丙戊酸钠对戊四氮致癎大鼠海马Bax和Bcl-2表达的影响

目的探讨丙戊酸钠(VAP)对戊四氮(PTZ)致癎大鼠海马Bax和Bcl-2表达的影响.方法将24只成年Wistar大鼠随机分为正常对照(NC)组、PTZ组和VAP组,PTZ组和VAP组大鼠腹腔注射阈下剂量的PTZ 35 mg/(kg·d),直至达到点燃标准.点燃后,VAP组大鼠经腹腔注入VAP 15 mg/(kg·d),PTZ组大鼠经腹腔注入生理盐水,30 min后,再腹腔注射PTZ诱发癫癎发作.应用免疫组化法检测大鼠海马神经元Bax和Bcl-2蛋白的表达.结果大鼠海马神经元Bax阳性细胞数和光密度,PTZ组均明显高于VAP组和NC组(均P<0.01),VAP组明显高于NC组(P<0.05);大鼠海马神经元Bcl-2阳性细胞数和光密度,PTZ组明显高于NC组(P<0.05),VAP组均明显高于PTZ组和NC组(均P<0.01).结论 VAP可以增强癫癎大鼠海马神经元Bcl-2的表达和降低Bax的表达,有对抗癫癎发作导致细胞凋亡的作用.     

丙戊酸对癫癎大鼠海马兴奋性氨基酸类神经递质动态释放的影响

目的:观察丙戊酸(valproate,VPA)对戊四氮(pentylenetetrazol,PTZ)点燃的自由活动大鼠海马胞外兴奋性氨基酸类神经递质动态释放过程的影响。方法:建立大鼠慢性癫癎模型及自由活动的清醒动物脑内在体微透析(microdialysis,MD)模型,用高效液相色谱测定急性腹腔注射VPA 200 mg·kg-1对大鼠海马胞外兴奋性氨基酸类神经递质释放的影响。结果:在惊厥发作期及发作间期,自由活动大鼠海马胞外谷氨酸及天冬氨酸水平显著上升,给予VPA 200 mg·kg-1后,两者浓度明显下降。结论:①VPA对海马胞外主要的兴奋性氨基酸类神经递质释放的调控为其发挥抗癎作用的重要机制之一;②在VPA对CNS兴奋性氨基酸类神经化学递质调控机制的研究中,PTZ点燃的大鼠癫癎模型较为理想。     

抗癫痫药物对大鼠记忆和学习功能影响的研究

目的探讨抗癫痫药物对大鼠认知功能的影响。方法健康雄性性成熟SD大鼠70只,随机分为正常对照组(NS组)、癫痫对照组(PTZ组)、卡马西平(CBZ)组、苯妥英钠(PHT)组、丙戊酸钠(VPA)组、妥泰(TPM)组及拉莫三嗪(LTG)组,每组10只。除NS组外其他6组用PTZ点燃。抗癫痫治疗2周后用Morris水迷宫测试认知功能。采用方差分析进行统计学处理。结果PTZ组学习成绩提高快(P<0.05,P<0.01)。卡马西平组、丙戊酸钠组、拉莫三嗪组测试成绩捉高很快(P<0.01),优于NS组。苯妥英钠组测试成绩提高较慢(P<0.05),与NS组比较无明显差异。妥泰组测试成绩提高慢,各次、各天之间差异无显著性(P>0.05),较NS组差。在寻找平台象限和在平台象限逗留时间的测试中,妥泰寻找时间最长,逗留时间最短,两项成绩均低于其他组(P<0.05,P<0.01);其他各组之间差异无显著性。结论PHT可能损害大鼠的学习、判断功能,TPM还可损害大鼠的记忆功能。     

法舒地尔对戊四氮点燃大鼠海马丝切蛋白及苔藓纤维出芽的影响

目的 探讨法舒地尔对戊四氮(PTZ)点燃大鼠海马组织中丝切蛋白(cofilin,非磷酸化形式)表达与苔藓纤维出芽程度关系的影响.方法 210只SD雄性大鼠分成戊四氮组、法舒地尔干预组和生理盐水对照组,采用PTZ慢性点燃癫癎模型,应用SABC法检测cofilin表达,用Timm染色检测苔鲜纤维出芽情况.结果 PTZ组大鼠点燃率、病死率与法舒地尔组比较差异无统计学意义.PTZ组和法舒地尔组CA3区苔藓纤维出芽评分差异无统计学意义,与对照组相比差异均有统计学意义(P＜0.05).PTZ组和法舒地尔组海马非磷酸化cofilin表达差异无统计学意义.结论 丝切蛋白可能通过苔藓纤维出芽与癫癎的发生相关.     

戊四氮点燃癫癎大鼠海马5-羟色胺能神经递质的动态研究

目的：观察戊四氮（PTZ）点燃癫癎形成过程中大鼠海马5-羟色胺（5-HT）能神经递质的变化。方法：用PTZ制作癫癎大鼠模型,将造模成功大鼠分为戊四氮急性发作组（PTZ 1组）和戊四氮慢性点燃组（PTZ 2组）,同时设立对照组（腹腔注射生理盐水）。在体微透析取样,观察大鼠行为、脑电图（EEG）和海马5-HT能神经递质的变化。结果：PTZ 1组癫癎发作时EEG自发放电逐级加重;癫癎发作时海马5-HT水平与对照组、发作前和发作后比较显著升高（P〈0.05）;海马5-羟吲哚乙酸（5-HIAA）水平差异无统计学意义;5-HT转化率（5-HIAA/5-HT）降低,差异有统计学意义（P〈0.05）。PTZ 2组点燃后大鼠出现自发癫癎发作,EEG在发作间期出现自发放电;5-HT和5-HIAA水平在点燃期、维持点燃期、对照组间比较差异有统计学意义（P〈0.05）。结论：大鼠癫癎发作时海马5-HT水平显著升高,发作后恢复正常;在癫癎形成过程中,早期5-HT水平一过性升高、PTZ点燃后和发作间期海马5-HT水平逐渐降低。     

单胺类递质在迷走神经刺激抗癫痫中的作用研究

目的探讨迷走神经刺激（ｖａｇｕｓｎｅｒｖｅｓｔｉｍｕｌａｔｉｏｎ,ＶＮＳ）抗癫痫的作用机制。方法成年健康Ｗｉｓｔａｒ大鼠３０只,随机分为正常对照组（ＮＣ组）、戊四氮（ｐｅｎｔｙｌｅｎｅｔｅｔｒａｚｏｌ,ＰＴＺ）致癫痫组（ＰＴＺ组）及ＶＮＳ后ＰＴＺ致癫痫组（ＶＮＳ组）。ＰＴＺ腹腔注射致癫痫后（６０ｍｇ／ｋｇ体重）,行左侧颈部迷走神经刺激。采用荧光光度法测定各组动物大脑顶叶皮层及海马的去甲肾上腺素（ＮＡ）、肾上腺素（Ａ）及五羟色胺（５ＨＴ）的含量。结果顶叶皮层Ａ及５ＨＴ的含量ＰＴＺ组明显高于ＮＣ组,而ＶＮＳ组则明显低于ＰＴＺ组;海马内ＮＡ、Ａ及５ＨＴ的含量ＰＴＺ组明显低于ＮＣ组,而ＶＮＳ组ＮＡ及５ＨＴ含量明显高于ＰＴＺ组。行为和ＥＥＧ结果显示,ＶＮＳ有明显的抗癫痫作用。结论单胺类递质ＮＡ、Ａ及５ＨＴ在ＶＮＳ抗癫痫中起重要作用。     

Effects of Antiepileptic Drugs on GABA Responses and on Reduction of GABA Responses by PTZ and DMCM on Mouse Neurons in Cell Culture

The mechanisms of action of antiepileptic drugs effective against generalized absence seizures (antiabsence AEDs) remain uncertain. Antiabsence AEDs are generally effective against seizures induced in experimental animals by pentylenetetrazol (PTZ) and methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), drugs which reduce GABAergic inhibition. Thus, antiabsence AEDs have been suggested to enhance GABAergic inhibition. We studied the effects of several AEDs on GABA responses recorded from mouse spinal cord neurons grown in primary dissociated cell culture. Four antiabsence AEDs were included: ethosuximide (ESM), dimethadione (DMO), sodium valproate (VPA), and diazepam (DZP). Two experimental AEDs, CGS 9896 and ZK 91296, with anticonvulsant action against PTZ- or DMCM-induced seizures were also included. Possible effects of the antiabsence and experimental AEDS on PTZ- and DMCM-induced inhibition of GABA responses were also evaluated. PTZ and DMCM reversibly reduced GABA responses in a concentration-dependent manner. PTZ completely inhibited GABA responses at 10 mM (IC50 of 1.1 mM), whereas DMCM-induced inhibition of GABA responses reached a plateau level of 39% of control values at 1 microM (IC50 of 33 nM). ESM (1,200 microM), DMO (6 mM), VPA (200 microM), CGS 9896 (2 microM), and ZK 9896 (2 microM) did not alter GABA responses. DZP enhanced GABA responses in a concentration-dependent manner. The inhibition of GABA responses produced by PTZ 1 mM was unaltered by ESM (600 microM), DMO (6 mM), CGS 9896 (1 microM), or ZK 9896 (1 microM). Coapplication of VPA (200 microM) and PTZ (1 mM) slightly enhanced the PTZ effect. DZP (greater than 10 nM), however, reversed the PTZ-induced reduction of GABA responses.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of seizure susceptibility in pilocarpine epileptic and nonepileptic Wistar rats and of seizure reinduction with pentylenetetrazole and electroshock models

Purpose:   Pentylenetetrazole (PTZ) and maximal electroshock (MES) models are often used to induce seizures in nonepileptic control animals or naive animals. Despite being widely used to screen antiepileptic drugs (AEDs), both models have so far failed to detect potentially useful AEDs for treating drug-resistant epilepsies. Here we investigated whether the acute induction of MES and PTZ seizures in epileptic rats might yield a distinct screening profile for AEDs.
Methods:   Status epilepticus (SE) was induced in adult male Wistar rats by intraperitoneal pilocarpine injection (Pilo, 320 mg/kg, i.p.). One month later, controls or naive animals (Cont) that did not develop SE postpilocarpine (N-Epi) and pilocarpine-epileptic rats (Epi) received one of the following: phenobarbital (PB, 40 mg/kg), phenytoin (PHT, 50 mg/kg), or valproic acid (VPA, 400 mg/kg). Thirty min later the animals were challenged with either subcutaneous MES or PTZ (50 mg/kg, s.c.).
Results:   VPA, PB, and PHT were able to prevent MES in all groups tested (Cont, N-Epi, and Epi groups), whereas for the PTZ model, only the Cont group (naive animals) had seizure control with the same AEDs. In addition, Epi and N-Epi groups when challenged with PTZ exhibited a higher incidence of severe seizures (scores IV-IX) and SE (p   <   0.05, Fisher's exact test).
Conclusions:   Our findings suggest that the induction of acute seizures with PTZ, but not with MES, in animals pretreated with pilocarpine (regardless of SE induction) might constitute an effective and valuable method to screen AEDs and to study mechanisms involved in pharmacoresistant temporal lobe epilepsy (TLE).     

Behavioral characterization of pentylenetetrazol-induced seizures in the marmoset

This study was designed to characterize seizures induced with pentylenetetrazol (PTZ) in marmosets. Thirteen adult marmosets (Callithrix sp.) received 20, 30, or 40 mg/kg of PTZ intraperitoneally. PTZ caused all animals to switch their natural behavioral repertoire to early convulsive behavior. Seizure scores were low at lower PTZ doses, whereas the highest dose of PTZ led to seizure scores IV and V (according to Racine's scale) in 69% of animals. To further characterize the model we performed a preliminary evaluation of the efficacy of three antiepileptic drugs: phenobarbital, phenytoin, and carbamazepine. Phenobarbital prevented PTZ-induced seizures in 100% of trials. As expected, phenytoin and carbamazepine were not effective against PTZ-induced seizures. The present study describes the PTZ model of seizures in marmosets with a drug-response profile similar to that of the rodent model, thus bringing to a well-known model (PTZ in rodents) the complexity of a nonhuman primate brain.     

雷帕霉素对未成年癫痫模型大鼠的毒性作用

目的利用戊四氮(pentylenetetrazol,PTZ)慢性点燃Sprague Dawley大鼠(SD大鼠)模型观察在点燃初期腹腔注射雷帕霉素(rapamycin,RAPA)能否抑制癫痫发生以及雷帕霉素在治疗中的安全性。方法将6~8周龄SD雄性大鼠随机分为雷帕霉素干预组PTZ+RAPA及其对照组PTZ+NS(normal saline)及NS组,观察1周(w)、2周(w)、4周(w)、6周(w)共4个时间点,每亚组12只,观察实验动物体质量的变化、死亡率及癫痫发作情况。结果各组实验大鼠的死亡率:PTZ+RAPA组为22.9%,PTZ+NS组为10.4%,NS组为0%。PTZ+RAPA组与PTZ+NS组各个相对应的时间点(1 w,2 w,4 w,6 w)体质量差均有统计学差异(P0.001)。6周时PTZ+RAPA组的点燃率为66.7%,PTZ+NS组的点燃率为58.3%,二者无统计学差异(P0.05)。PTZ+RAPA组与PTZ+NS组相对应时间点(1 w,2 w,4 w,6 w)发作分值的两两比较差异无统计学意义(P0.05)。结论雷帕霉素未能减少或抑制未成年大鼠的癫痫发作,但能明显降低未成年SD大鼠的体质量,可能有一定的毒副作用。     

Timed pentylenetetrazol infusion test: a comparative analysis with s.c.PTZ and MES models of anticonvulsant screening in mice.

The intravenous pentylenetetrazol (i.v.PTZ) seizure test provides threshold dose for induction of seizures in individual animals. In the present study, the i.v. and s.c.PTZ seizure models in mice were compared for seizure pattern, intra- and interanimal variability. Anticonvulsant activities of several antiepileptic drugs (AEDs) at non-ataxic dose levels were evaluated in the PTZ and maximal electroshock (MES) seizure tests. In the i.v.PTZ test, at 0.5 ml/min rate of administration, the mean threshold PTZ doses for induction of clonus and tonic extensor were 44.17 and 99.59 mg/kg, respectively. The intra- and interanimal variabilities in the seizure response were low in the i.v.PTZ as compared to the s.c.PTZ model. Phenobarbital sodium, ethosuximide, sodium valproate, diazepam, tiagabine, oxcarbazepine and zonisamide enhanced threshold or onset latency for clonus in the i.v. and s.c.PTZ tests, respectively. Levetiracetam and pregabalin were active in the i.v.PTZ test, but had no effect in the s.c.PTZ test. Ability of AEDs to protect from tonic extensor was compared in the MES and i.v.PTZ tests. For this effect, phenobarbital sodium, phenytoin, carbamazepine, sodium valproate, gabapentin, oxcarbazepine, zonisamide and pregabalin were effective in the i.v.PTZ and MES tests. Ethosuximide, diazepam and levetiracetam were effective in the i.v.PTZ test, but not the MES test. On the contrary, lamotrigine and topiramate were active in the MES, but not the i.v.PTZ test. These results indicate that it is advantageous to use i.v.PTZ test as an acute seizure model for screening of antiepileptic drugs. This model can identify molecules with varied mechanism of action and broad clinical utility in the treatment of epilepsy.     

The role of technical, biological and pharmacological factors in the laboratory evaluation of anticonvulsant drugs. III. Pentylenetetrazole seizure models

Although seizure models using systemic administration of the chemoconvulsant pentylenetetrazol (PTZ) for induction of generalized clonic seizures in rodents are widely employed to identify potential anticonvulsants, the important role of diverse technical, biological and pharmacological factors in interpretation of results obtained with these models is often not recognized. The aim of this study was to delineate factors other than sex, age, diet, climate, and circadian rhythms, which are generally known. For this purpose, experiments with 8 clinically established antiepileptic drugs were undertaken in the following PTZ models: (1) the threshold for different types of PTZ seizures, i.e., initial myoclonic twitch, generalized clonus with loss of righting reflexes, and tonic backward extension of forelimbs (forelimb tonus), in mice; (2) the traditional PTZ seizure test with s.c. injection of the CD97 for generalized clonic seizures in mice; and (3) the s.c. PTZ seizure test in rats. In rats, in addition to evaluating drug effects on generalized clonic seizures, a ranking system was used to determine drug effects on other seizure types. When drugs were dissolved in vehicles which themselves did not exert effects on seizure susceptibility, the most important factors which influenced drug potencies were: (1) bishaped dose-response curves, i.e., a decline in anticonvulsant dose-response at high doses of some drugs, leading to misinterpretations of drug efficacy if only a single high drug dosage is tested; (2) effects of route of PTZ administration (i.v. infusion vs. s.c. injection) on estimation of anticonvulsant potency; (3) species differences in drug metabolism; (4) differences in drug potencies calculated on the basis of administered doses compared to potency calculations based on 'active' drug concentrations in plasma; (5) qualitative and quantitative species differences in drug actions; (6) endpoints used for PTZ tests; (7) misleading predictions from PTZ seizure models. Analysis of anticonvulsant drug actions indicated that myoclonic or clonic seizures induced by i.v. or s.c. PTZ might be suitable for predicting efficacy against myoclonic petit mal seizures in humans, but certainly not to predict efficacy against absence seizures. Tonic seizures induced by PTZ were blocked by drugs, such as ethosuximide, which exert no effect on tonic seizures in humans. In order to reduce the variability among estimates of anticonvulsant activity in PTZ seizure models, the various factors delineated in this study should be rigidly controlled in experimental situations involving assay of anticonvulsant agents.     

Anticonvulsant effect of retigabine during postnatal development in rats

Retigabine is a new-generation antiepileptic drug that exerts therapeutic action through the activation of KCNQ channel dependent M-type potassium currents. While retigabine has been extensively studied in adult animals using a wide variety of seizure models, its effects in developing animals have not been examined. There has only been one previous report of retigabine efficacy in juvenile rats (Mazarati et al., 2008), which examined efficacy against kindled seizures and did not examine ages younger than postnatal day (P) 14. To determine the efficacy of retigabine during brain development we pretreated rats with retigabine (0-30 mg/kg) at three ages corresponding to the neonatal period through late childhood/early adolescence (i.e., P7, P14, or P25). Seizures were induced 30 min later using a chemoconvulsant (pentylenetetrazol, PTZ) model, which has been widely used to determine anticonvulsant efficacy of many other antiepileptic drugs in neonatal animals. In a dose and age-dependent manner, retigabine reduced the severity of PTZ evoked seizures, increased the latency to seizure onset, and decreased the incidence of full maximal seizures. The minimum effective dose was found to be 5mg/kg for P7 animals, 2.5mg/kg for P14 animals, and 1mg/kg for P25 animals. These findings allow a direct comparison between retigabine and previously studied antiepileptic drugs against PTZ seizures during development, and provide the first report of the effective dose range of retigabine in neonatal animals.