红藻氨酸致痫后大鼠海马ERK、P38 MAPK和JNK的活性变化

目的研究红藻氨酸(KA)诱导大鼠癫痫发作后海马组织细胞外调节蛋白激酶(ERK)、p38MAPK和c-jun氨基末端激酶(JNK)的活性(磷酸化状态)的变化情况。方法立体定向大鼠侧脑室内注射KA引起大鼠癫痫发作,采用Western-blot方法观察KA致痫后大鼠海马中活性ERK、p38MAPK和JNK的变化。结果KA诱导大鼠癫痫发作后,海马组织ERK、p38MAPK和JNK的磷酸化水平开始增高,分别于30min、1h和30min后达高峰,呈对照组的4.76倍、2.16倍和3.95倍,两组比较差异具有显著性(P<0.01),之后逐渐下降。结论KA致痫大鼠癫痫发作后,海马组织MAPKs的活性产生变化,其信号通路可能参与癫痫发作后海马组织的病理生理反应过程。     

GABA受体基因转染对癫痫大鼠海马区病理变化的影响

目的探讨在下丘脑乳头体上核内转染γ-氨基丁酸(GABA)受体基因后对海人藻酸(KA)致痫大鼠海马病理变化的影响,从而为难治性癫痫的治疗开辟新的途径。方法在右侧杏仁核内注射KA制备癫痫动物模型作对照,GABA基因转染组则利用仙台病毒(HVJ)-脂质体转染法预先在下丘脑的乳头体上核内转染被脂质体包被的GABA受体基因,48h后在杏仁核内注射KA,两组大鼠分别进行HE染色观察。结果 GABA基因转染组大鼠海马区病理改变较KA对照组明显减轻。结论下丘脑内转染GABA受体基因后可以抑制癫痫发作的程度。     

苯甲酸雌二醇预处理的去势大鼠致癇前后血清雌二醇和海马组织雌激素β受体的变化

目的：分析不同剂量苯甲酸雌二醇（EB）预处理的去势大鼠以海人藻酸（kainic acid，KA）致痫前后血清雌二醇（E2）和海马组织雌激素β受体（ERβ）的水平，探讨E2、ERβ与KA之间的相关性。方法：将去势大鼠随机分为对照组（O组）、不同剂量EB干预组（O＋E）、致痂组（O＋KA）和不同剂量EB预处理致痫组（O＋E＋KA）。分别利用电化学发光法与免疫印迹法检测E2浓度与海马组织ERβ表达水平的变化。结果：①除小剂量EB（25μg&#183;kg^-1）预处理的去势大鼠血清E2水平（88．8&#177;3．23）pmol&#183;L^-1与O组（88．49&#177;8．31）pmol&#183;L^-1差异无统计学意义外，其余剂量EB预处理（≥EB 1mg&#183;kg^-1）的各组去势大鼠血清E2浓度均明显高于O组，且E2水平随EB的增加而增高，但不影响去势大鼠海马组织ERβ的表达。②癫痫发作的早期（癫瘸发作后2h内）不仅降低了癫痫动物血清雌激素的水平，也降低了海马组织ERβ的表达，但这种降低与癫痫发作的轻重程度无关。结论：去势大鼠海马ERβ蛋白的表达水平主要与癫痫发作有关，雌激素对癫痫发作的影响可能并不体现在其对ERβ表达的影响。     

海人酸致癫痫持续状态后大鼠海马中Caspase-3动态表达变化研究

目的 观察海人酸(kainite acid,KA)致癫痫发作后大鼠海马中Caspase-3的动态变化,以便及时进行干预并控制凋亡的发生.方法 海人酸(KA)致痫急性发作后分别在12 h、24 h、3 d、7 d,采用免疫组化法计算阳性细胞的平均光密度值;Nissle染色法检测神经细胞丢失坏死情况;Westernblot方法检测海马组织中Caspase-3表达情况.结果 致痫后Caspase-3表达趋势在12 h开始表达增高,24 h～3 d达到高峰,3～7 d后明显下降,3 d对神经细胞表现典型的凋亡状态,明显高于对照组(P＜0.05).结论 癫痫持续状态(Status epilepticus,SE)同时上调了Caspase-3的表达,可导致神经细胞发生凋亡,为癫痫的神经保护治疗提供了理论依据.     

海马内注射内皮素-1导致大鼠痫性发作和海马硬化的初步研究

目的 观察大鼠海马内注射内皮素(endothelin,ET)-1是否导致大鼠痫性发作和海马硬化.方法 立体定位在成年大鼠海马CA3区内分别注射1 μL ET-1(200 pmol,15只)、海人酸(kainate,KA 5 pmol,15只)或磷酸盐缓冲液(PBS,0.01 mol,8只),观察大鼠行为学、脑电及对侧海马病理学改变.结果 海马注射PBS后大鼠未见痫性发作,脑电图呈10～15 Hz、150-200μV基本节律.注射ET-1或KA 2 h内大鼠出现不同程度的痫性发作和脑电图异常改变(尖波或尖慢波),KA组3-5级发作率高于ET-1组(86.67% vs 16.67%,P<0.05).部分ET-1和KA组大鼠在给药后2～3周可见癫痫样发作行为学改变.与PBS组比较,El-1和KA组给药后48 h对侧海马各区Nissl染色细胞数明显减少,GFAP表达增强(P<0.05);给药后30 d,对侧CA3区和门齿区苔藓纤维出芽评分高于PBS组(P<0.05).结论 海马注射ET-1可以导致大鼠癫痫样行为改变和海马硬化.     

海人酸致痫大鼠海马神经元凋亡研究

目的　研究大鼠癫痫发作后海马神经元凋亡的时空分布。方法　采用海人酸 (KA)诱导大鼠癫痫模型 ,以原位末端标记 (TUNEL)及透射电镜检测癫痫发作后 6h、1d、3d、7d海马神经元凋亡。结果　对照组及KA致痫后 6h组 ,海马区均未发现凋亡细胞。KA致痫后 1d ,海马CA1、CA3及CA4区开始出现凋亡细胞 ,3d时明显增多 ,7d时最多。KA致痫后 1d、3d、7d ,海马CA1锥体层线性长度1mm的TUNEL阳性细胞数分别为 (6 .6 0± 3.6 9)个、(13.5 7± 5 .17)个和 (2 5 .96± 4 .87)个 ;CA3区分别为 (6 .4 8± 2 .4 5 )个、(13.89± 2 .5 2 )个和 (2 8.80± 5 .39)个 ;CA4区分别为 (4 .6 0± 1.4 5 )个、(12 .2 0± 2 .0 4 )个和 (2 5 .2 0± 5 .83)个。 3个时间组相应区域凋亡神经元数比较均存在显著性差异(P <0 .0 0 1)。透射电镜观察可见典型的凋亡细胞形态学改变。结论　凋亡参与KA致痫大鼠癫痫发作后海马神经元迟发性死亡过程。     

雌激素和姜黄素对海人酸杏仁核点燃大鼠行为学、脑电图及海马神经元损伤的影响

目的了解雌激素和姜黄素对海人酸(kainic acid,KA)杏仁核点燃大鼠癫痫发作的影响。方法给去势的雌性大鼠添加雌激素治疗,添加姜黄素治疗,或添加雌激素和姜黄素治疗,比较各组大鼠致痫后癫痫发作的行为学、脑电图和海马神经元损伤的变化。结果给雌激素治疗的大鼠重型发作(Racine 4/5级)评分最高,而雌激素加姜黄素治疗组评分最低(P<0.05)。脑电图的变化与行为学的改变基本一致。致痫后大鼠注射KA侧海马CA3区、CA4区可见到明显的细胞损伤,而该侧海马CA1区、齿状回区(DG)及对侧海马CA3区、CA1区及DG区神经元损害不明显。雌激素组大鼠双侧海马CA3区均出现加重的神经元损害,姜黄素组及雌激素加姜黄素组大鼠海马注射对侧CA3区存活神经元较雌激素组明显增加(P<0.01)。结论高水平的雌激素可以加重癫痫的发作,给姜黄素治疗可以减轻大鼠海马CA3区神经元损害。     

GABA受体基因转染对癫痫大鼠皮层脑电的影响

目的探讨在下丘脑乳头体上核内转染γ-氨基丁酸(GABA)受体基因后对海人藻酸(KA)致痫大鼠皮层脑电产生的影响,从而为难治性癫痫的治疗开辟新的途径。方法在右侧杏仁核内注射KA制备癫痫动物模型作对照,GABA基因转染组则利用仙台病毒(HVJ)-脂质体转染法预先在下丘脑的乳头体上核内转染被脂质体包被的GABA受体基因,48h后在杏仁核内注射KA,两组大鼠分别进行皮层脑电测定。结果KA致痫组大鼠脑电在尖波的背景上出现持续性放电,GABA转基因组大鼠则以散发的尖波、棘波以及阵发性放电为主,出现持续性放电的时间明显缩短。结论下丘脑内转染GABA受体基因后可以抑制癫痫发作的程度。     

红藻氨酸致痫大鼠海马神经元凋亡及其与caspase-3关系的研究

目的　研究大鼠癫痫发作后海马神经元凋亡及其与天冬氨酸特异性半胱氨酸蛋白酶 -3 (cysteinylasparate-specific proteinase,caspase-3 )表达的关系。方法　采用红藻氨酸 (kainic acid,KA)诱导大鼠癫痫模型 ,以原位末端标记 (TUNEL)及透射电镜检测癫痫发作后 6h及 1、3、7d海马神经元凋亡 ;半定量 RT-PCR及免疫组化法检测 caspase-3 m RNA及 caspase-3阳性表达。结果　KA致痫后 1 d,海马 CA1、CA3及 CA4区开始出现凋亡细胞 ,3 d时明显增多 ,7d时最多。 3个时间组相应区域间凋亡神经元数比较差异均有显著性 (P<0 .0 0 1 )。透射电镜观察可见典型的凋亡细胞形态学改变。 RT-PCR结果显示 ,KA致痫后 6h,海马组织 caspase-3 m RNA表达较对照组显著增高 (P <0 .0 5 ) ,1、3、7d caspase-3 m RNA仍持续高水平表达 (P <0 .0 5 )。免疫组化结果显示 ,KA致痫后 1 d,海马 CA1、CA3、CA4区开始出现 caspase-3阳性表达 ,3 d时阳性表达进一步增强 ,7d时表达最强。结论　凋亡参与 KA致痫大鼠癫痫发作后海马神经元迟发性死亡过程 ,caspase-3可能在癫痫后神经元凋亡过程中具重要的作用。     

迷走神经刺激对癫痫大鼠行为及脑电图的影响

目的：观察颈部迷走神经干电刺激对癫痫大鼠行为及额叶、海马、杏仁核脑区放电的影响，为迷走神经刺激（Vagus Nerve Stimulation,VNS)抗痫机制研究提供理论依据。方法：利用脑立体定位手段，将电极埋入大鼠脑部双侧额叶皮质、海马和杏仁核，记录VNS前后由红藻氨酸（KA）诱发复杂部分性癫痫大鼠脑电变化并观察动物行为的改变。结果：VNS后大鼠癫痫强直－阵挛发作次数明显减少，首次发作潜伏期延长，癫痫发作平均持续时间缩短；VNS尤其对杏仁核放电有明显的抑制作用。结论：VNS能有效抑制KA诱发的复杂部分性癫痫发作，并且杏仁核可能是抑痫作用的关键核因。     

雌激素影响海人酸杏仁核点燃大鼠癫(癎)发作机制的初步探讨

目的:探讨雌激素(E)和姜黄素(C)影响癫发作的机制。方法:用E和C单独及联用连续处理去势雌性大鼠5d,第6天以海人酸(KA)杏仁核点燃法制备癫大鼠模型,观察大鼠癫发作的行为学表现,用免疫组化方法检测海马组织c-Jun蛋白的表达。结果:E加C组(EC KA组)大鼠癫重度发作的严重程度较E组(E KA组)明显减轻(P<0.05)。E KA组海马中c-Jun蛋白表达最多,C组(C KA组)及对照组(KA组)均表达较少且没有任何差异;EC KA组海马的CA1区c-Jun蛋白表达较E KA组明显减少(P<0.05)。结论:C能一定程度上减轻E引起的癫发作加重,它可能通过抑制c-Jun/核转录因子激活蛋白-1(activate-protein1,AP-1)活性,使E作用的AP-1通路受阻,从而减轻了E的促神经元兴奋作用。     

红藻氨酸诱导癫痫发作大鼠海马EphA5受体及其配体ephrinA3基因表达变化的研究

目的研究在红藻氨酸(Kainic acid,KA)诱导的损伤型颞叶癫痫(Mesial temporal lobe epilepsy,MTLE)的大鼠海马中,轴突导向因子EphA5受体及其配体ephrinA3基因表达的变化,探讨EphA5/ephrinA3与癫痫后海马兴奋性神经网络形成的作用和关系。方法侧脑室内微量注射KA,建立KA诱导的成年大鼠MTLE模型,用原位杂交法检测癫痫发作1d、1周、2周、3周、4周大鼠海马内EphA5/ephrinA3 mRNA的表达,定量分析表达的动态变化。结果EphA5/ephrinA3 mRNA于癫痫发作后1周,在海马齿状回颗粒细胞层和CA_3区锥体细胞层开始增强,2周达到高峰,4周恢复接近对照组水平。结论在KA所致的癫痫持续状态(Status epilepsy,SE)中,海马神经元通过增强EphA5/ephrinA3 mRNA的表达。调控MTLE大鼠海马内苔藓纤维和突触的重建,是癫痫后海马新的稳定的异常兴奋性神经网络形成的可能机制。     

戊四氮致痫对大鼠海马星形胶质细胞的影响

目的　探讨戊四氮（ＰＴＺ）致痫对大鼠海马星形胶质细胞的影响。方法　应用免疫组织化学方法观察ＰＴＺ致痫后大鼠海马内胶原纤维酸性蛋白（ＧＦＡＰ）变化的特点,同时观察了不同强度的痫性发作与ＧＦＡＰ改变的关系。结果　ＧＦＡＰ改变于ＰＴＺ致痫后１２ｈ 开始,２４ｈ 达到高峰,７２ｈ 已开始回落,并且痫性发作的强度与ＧＦＡＰ改变有一定的联系。结论　癫痫与星形细胞之间确有一定联系。     

颞叶癫(癎)大鼠(癎)性发作后神经元特异性烯醇化酶、髓鞘碱性蛋白的变化及其意义

目的观察神经元特异性烯醇化酶(NSE)、髓鞘碱性蛋白(MBP)在海人酸(KA)颞叶癫癎大鼠癎性发作后各时间点血液中的动态变化,探讨颞叶癫癎发作后脑神经元和神经髓鞘损伤程度。方法KA注射大鼠海马部位建立颞叶癫癎模型,在癎性发作后3h、6h、12h、24h、48h、72h抽取血液,测定其血清中NSE、MBP含量。结果癫癎发作后NSE和MBP含量逐渐增高,24hNSE含量最高,72hMBP含量最高。结论癫癎发作后存在神经元损伤和坏死,继之出现脑白质神经髓鞘损伤。     

Effects of topiramate on seizure susceptibility in kainate-kindled rats: involvement of peripheral-type benzodiazepine receptors.

This study was aimed to quantitatively evaluate the effects of topiramate (TPM) on seizure susceptibility and hippocampal peripheral-type benzodiazepine receptors (PBRs) in the kainic acid (KA) model of temporal lobe epilepsy. Male rats were randomized into saline control group, KA group, KA/TPM low dose group and KA/TPM high dose group. Three weeks after single injection of KA (10 mg kg(-1), sc), the effects of TPM were tested at two doses (10 and 30 mg kg(-1), sc) once a day for 1 week in KA/TPM low dose group or KA/TPM high dose group, respectively. Rats in KA group received comparable injections of saline. Four weeks after initial KA injection, a subconvulsant dose KA (5 mg kg(-1), sc) was administered in rats in these three groups. Rats in saline control group received equal volume of saline. All animals were decapitated and hippocampus synaptosomes were purified 180 min after behavioral observation. PBRs specific binding sites were assessed by an in vitro binding technique utilizing the highly selective ligand [(3)H]PK11195. Seizure threshold was elevated and specific PBRs binding in hippocampus was decreased by TPM in dose-dependent manner. Specific PBRs binding in hippocampus was significantly related to seizure latency and seizure intensity. These results suggest that TPM can reduce the susceptibility to seizures in KA-kindled rats and its anticonvulsant effect seems resulting from, at least in part, the reduced PBRs binding after treatment. These results also support the hypothesis that PBRs represent a novel target for antiepileptic drug development.     

Long‐lasting pro‐ictogenic effects induced in vivo by rat brain exposure to serum albumin in the absence of concomitant pathology

Purpose: Dysfunction of the blood–brain barrier (BBB) is a common finding during seizures or following epileptogenic brain injuries, and experimentally induced BBB opening promotes seizures both in naive and epileptic animals. Brain albumin extravasation was reported to promote hyperexcitability by inducing astrocytes dysfunction. To provide in vivo evidence for a direct role of extravasated serum albumin in seizures independently on the pathologic context, we did the following: (1) quantified the amount of serum albumin extravasated in the rat brain parenchyma during status epilepticus (SE); (2) reproduced a similar concentration in the hippocampus by intracerebroventricular (i.c.v.) albumin injection in naive rats; (3) measured electroencephalography (EEG) activity in these rats, their susceptibility to kainic acid (KA)–induced seizures, and their hippocampal afterdischarge threshold (ADT). Methods: Brain albumin concentration was measured in the rat hippocampus and other forebrain regions 2 and 24 h after SE by western blot analysis. Brain distribution of serum albumin or fluorescein isothiocyanate (FITC)‐albumin was studied by immunohistochemistry and immunofluorescence, respectively. Naive rats were injected with rat albumin or FITC‐albumin, i.c.v., to mimic the brain concentration attained after SE, or with dextran used as control. Inflammation was evaluated by immunohistochemistry by measuring glial induction of interleukin (IL)‐1β. Western blot analysis was used to measure inward rectifying potassium channel subunit Kir4.1 protein levels in the hippocampus. Seizures were induced in rats by intrahippocampal injection of 80 ng KA and quantified by EEG analysis, 2 or 24 h after rat albumin or dextran administration. ADT was measured by electrical stimulation of the hippocampus 3 months after albumin injection. In these rats, EEG was continuously monitored for 2 weeks to search for spontaneous seizures. Key Findings: The hippocampal serum albumin concentration 24 h post‐SE was 0.76 ± 0.21 μm . Similar concentrations were measured in other forebrain regions, whereas no changes were found in cerebellum. The hippocampal albumin concentration was similarly reproduced in naive rats by i.c.v. administration of 500 μg/4 μl rat albumin: albumin was predominantly detected extracellularly 2 h after injection, whereas at 24 h it was visible inside pyramidal neurons and in only a few scattered chondroitin sulphate proteoglycan (NG2)‐positive cells, but not in glial fibrillary acidic protein (GFAP)‐positive astrocytes or CR‐3 complement receptor (OX‐42)‐positive microglia. The presence of albumin in naive rat hippocampus was associated with induced IL‐1β in GFAP‐positive astrocytes and a concomitant tissue down‐regulation of Kir4.1. Spiking activity was evoked by albumin in the hippocampus lasting for 2 h. When KA was intrahippocampally applied either 2 or 24 h after albumin injection, the number of total interictal spikes in 3 h EEG recording was significantly increased by twofold on average. Three months after albumin injection, neither albumin nor inflammation was detected in brain tissue; at this time, the ADT was reduced by 50% but no spontaneous seizures were observed. Significance: Transient hippocampal exposure to albumin levels similar to those attained after prominent BBB breakdown resulted in increased seizure susceptibility and long‐term reduction in seizure threshold, but it did not evoke spontaneous seizures. These effects may be mediated by albumin‐induced astrocytes dysfunction and the associated induction of proinflammatory molecules.     

Ovarian steroid modulation of seizure severity and hippocampal cell death after kainic acid treatment

To determine whether maintained estrogen or progesterone levels affect kainic acid (KA) seizure patterns or the susceptibility of hippocampal neurons to death from seizures, ovariectomized Sprague-Dawley rats were implanted with estrogen pellets, 0.1 or 0.5 mg, that generated serum levels of 42.4 +/- 6.6 (mean +/- SEM) and 242.4 +/- 32.6 pg/ml or one to six capsules of progesterone that generated serum levels of 11.00 +/-.72 to 48.62 +/- 9.4 ng/ml. Seven days later, the rats were administered KA (8.5mg/kg, ip) and scored for seizure activity; 96 h later, the rats were killed and their brains processed for localization of neuron nuclear antigen (NeuN), a general neuronal marker. The hippocampus was scored for spread (the number of separate regions showing cell loss), and the area within the CA fields occupied by NeuN immunoreactivity was measured (indicating surviving neurons). Administration of estrogen or progesterone (independent of dose) significantly reduced mortality from KA seizures. Progesterone reduced seizure severity in animals that received one to four implants; compared with controls, no difference in seizure severity was noted for animals with six progesterone implants. The reduced seizures in progesterone-treated animals were accompanied by a reduction in the spread of hippocampal damage (r(2) = 0.87; P < 0.05). Likewise, in progesterone-treated rats, neuron survival and reduction in seizure scores were correlated (r(2) = 0.76; P < 0.0001). Estrogen had no effect on seizure severity (P > 0.05), but reduced both the spread (P < 0.05) and degree of neuronal loss (P < 0.05). Indeed, in the estrogen-treated rats, neuronal death was significantly lower than that observed in progesterone-treated animals with equally severe seizures (P < 0.05). These data are consistent with the hypothesis that progesterone produces its effects by reducing seizures, whereas estrogen has little beneficial effect on seizure behavior but protects the hippocampus from the damage seizures produce.     

Seizures in the intrahippocampal kainic acid epilepsy model: characterization using long‐term video‐EEG monitoring in the rat

Objective – Intrahippocampal injection of kainic acid (KA) in rats evokes a status epilepticus (SE) and leads to spontaneous seizures. However to date, precise electroencephalographic (EEG) and clinical characterization of spontaneous seizures in this epilepsy model using long‐term video‐EEG monitoring has not been performed. Materials and Methods – Rats were implanted with bipolar hippocampal depth electrodes and a cannula for the injection of KA (0.4 μg/0.2 μl) in the right hippocampus. Video‐EEG monitoring was used to determine habitual parameters of spontaneous seizures such as seizure frequency, severity, progression and day–night rhythms. Results – Spontaneous seizures were detected in all rats with 13 out of 15 animals displaying seizures during the first eight weeks after SE. A considerable fraction (35%) of the spontaneous seizures did not generalize secondarily. Seizure frequency was quite variable and the majority of the KA‐treated animals had less than one seizure per day. A circadian rhythm was observed in all rats that showed sufficient seizures per day. Conclusions – This study shows that the characteristics of spontaneous seizures in the intrahippocampal KA model display many similarities to other SE models and human temporal lobe epilepsy.