银杏叶提取物对癫癎大鼠海马结构胶质原纤维酸性蛋白免疫反应的影响

目的研究银杏叶提取物(GBE)对癫癎的干预作用及其对癫癎大鼠海马结构胶质原纤维酸性蛋白(GFAP)免疫反应 的影响。方法采用锂-匹罗卡品癫癎(LPS)大鼠模型。观察动物行为改变,应用免疫组化方法观察海马结构GFAP免疫反应活性 的变化。结果GBE对该模型癫癎发作的预防有效率和治疗有效率分别为94．44％和35．48％。GBE预处理组和GBE急性给药组 各时间点海马结构各亚区GFAP免疫反应阳性细胞数明显减少;GFAP-IR阳性细胞胞浆平均光密度明显增高。结论GBE预处理和 急性给药两种给药模式均有一定的抗LPS作用,前者明显优于后者。GBE抗LPS作用的机制可能与GBE能降低其星形胶质细胞反 应性有关。     

N-乙酰半胱氨酸通过介导m Calpain/TRPC6蛋白表达对癫痫大鼠学习认知功能的影响

目的探讨N-乙酰半胱氨酸对癫痫发作大鼠治疗后学习认知功能的影响及其机制。方法48只SD大鼠,随机分为对照组,癫痫组,N-乙酰半胱氨酸组(150mg·kg~(-1))和瞬时受体电位阳离子通道6 (TRPC6)抑制剂SKF96365组(0.06mg·kg~(-1)),每组12只。以匹罗卡品(300mg·kg~(-1))点燃大鼠癫痫发作,造模前7d,各组给对应剂量药物。观察匹罗卡品腹腔注射后0～180 min大鼠癫痫发作情况,癫痫发作3h后,给予7.5mg·kg~(-1)地西泮缓解癫痫发作。各组大鼠再继续给药观察7d,进行水迷宫测试,检测大鼠学习认知功能。水迷宫测试结束后取脑组织用于Nissl染色和Western Blot实验。结果行为学结果显示,匹罗卡品成功点燃大鼠癫痫发作,并造成大鼠认知功能损伤,而N-乙酰半胱氨酸与SKF96365能够缓解大鼠癫痫发作并改善大鼠认知功能损伤。与对照组相比,癫痫组中钙蛋白酶(mCalpain)蛋白和TRPC6蛋白表达显著升高,Nissl染色显示海马区神经元损伤。此外,癫痫组中,磷酸化的细胞外调节蛋白激酶(p-ERK)、磷酸化的环腺苷酸应答元件结合蛋白(p-CREB)和脑源性神经营养因子(BDNF)表达水平显著降低。然而,N-乙酰半胱氨酸的预给药和治疗能够降低mCalpain蛋白表达,抑制TRPC6蛋白表达,减少神经元凋亡,并增加p-ERK、p-CREB和BDNF蛋白表达。结论匹罗卡品能够点燃大鼠癫痫症状,并造成大鼠学习认知功能损伤,N-乙酰半胱氨酸通过抑制mCalpain蛋白表达,减少TRPC6激动,改善大鼠癫痫发作,此外,ERK/CREB/BDNF通路的激动与大鼠学习认知功能改善相关。     

己酮可可碱预处理对癫痫发作大鼠海马损伤的影响

目的观察己酮可可碱(Ptx)预处理对癫痫发作大鼠海马损伤的影响。方法健康、成年雄性Wistar大鼠分为3组:对照组、癫痫组和Ptx预处理组。对照组腹腔注射生理盐水(127mg·kg~(-1));癫痫组和Ptx组大鼠用氯化锂-匹罗卡品(Li-Pc)诱发癫痫发作,先腹腔注射氯化锂(127mg·kg~(-1)),20h后背部皮下注射匹罗卡品(15mg·kg~(-1));Ptx组大鼠在匹罗卡品注射前30min通过腹腔给予Ptx(60mg·kg~(-1))。观察大鼠癫痫发作情况,利用Timm和Thionin染色分别观察海马苔藓纤维发芽(MSF)和神经元损伤情况。结果癫痫组大鼠在海马苔藓纤维发芽明显增多,并伴有海马神经元的损伤和脱失,Ptx预处理降低了Li-Pc诱发大鼠的癫痫发作率和癫痫发作程度,延长了其癫痫发作潜伏期,减轻了Li-Pc诱发大鼠海马的苔藓纤维出芽及神经元的损伤。结论 Ptx预处理缓解了Li-Pc诱发大鼠的癫痫发作和海马损伤,可能成为治疗癫痫的一种方法。     

Nectin-1在锂-匹罗卡品癫痫大鼠海马中的表达

目的为探讨Nectin-1在癫痫形成中的作用,我们采用经典的氯化锂-匹罗卡品大鼠癫痫模型,在点燃持续状态后不同时间点观察Nectin-1蛋白在大鼠脑海马的表达变化规律。方法①选用正常成年雄性SD大鼠,随机分为正常对照组(n=10)与模型组(n=50),模型组采用氯化锂-匹罗卡品腹腔注射法,对照组用等量生理盐水腹腔注射。成功点燃后存活的大鼠以(3 d、1周、2周、4周、6周)为研究时间点随机分为5个亚组,每组10只。②用Western-blot、免疫组化等经典方法观察Nectin-1蛋白在癫痫大鼠模型中的表达变化及规律。结果实验组大鼠腹腔注射匹罗卡品后,经过急性发作期及潜伏期、慢性期,出现癫痫反复的自发性发作,对照组未见急性及慢性发作。免疫组化染色对照组Nectin-1蛋白主要在胞膜及胞浆表达,在海马CA3区深染区域集中于透明层(SL)。癫痫组2周、4周时Nectin-1在齿状回有较多的阳性细胞,主要表现为胞浆和核膜棕色,并向内分子层分布。Western-blot与对照组相比,在匹罗卡品诱导的SE之后2周表达升高,一直持续到慢性期4周、6周。结论Nectin-1蛋白在癫痫大鼠模型SE后慢性期海马组织中表达较正常增高,可能与癫痫的形成机制有关。     

代谢型谷氨酸受体亚型1基因在锂—匹罗卡品致痫大鼠齿状回中的长期高表达

目的:观察锂-匹罗卡品诱导的癫痫大鼠模型海马结构中代谢型谷氨酸受体亚型1(mGluRl)mRNA的动态表达变化。方法:用地高辛标记的多相寡核苷酸探针通过原位杂交方法检测海马各个区域在7d、14d和28d时mGluRlmRNA的表达。结果:在上述3个时间点齿状回mGluRlmRNA的表达明显上调,而在海马CA1区仅7d时可见mGluRl mRNA的相对上调,其余时间点无明显变化。结论:本研究提示锂-匹罗卡品癫痫模型齿状回mGluRl mRNA表达长期上调可能与海马结构的重塑和癫痫易感性形成有关。     

N-myc在大鼠急性痫性发作模型中的表达及其意义

目的 探讨在氯化锂-匹罗卡品诱导大鼠急性痫性发作模型中N-myc表达及其意义。方法健康Wistar雄性大鼠45只，随机分为生理盐水对照组、地西泮干预组和致痫1h～9d组(根据致痫后的不同时点分7个组)，共9组，每组5只。采用氯化锂-匹罗卡品联合腹腔注射急性致痫大鼠模型，常规脏染色观察实验大鼠脑组织的形态学改变，免疫组化染色法观察脑内N—myc表达产物分布及其含量变化。结果 致痫1d～9d组尤其致痫6d和9d两组可见到脑组织损伤性改变，海马区重于皮质区。生理盐水对照组N—myc几乎无表达，地西泮干预组低表达，致痫组表达增多，尤其以致痫1d组和致痫3d组最为明显。结论 急性痫性发作或癫痫持续状态可导致脑组织损伤性改变，以海马结构等易损区为明显。N—myc表达及其表达量可能与急性痫性发作后脑损伤及其受累部位有关。     

TLR9、MyD88在颞叶癫痫大鼠海马组织中表达的动态变化

目的观察氯化锂-匹罗卡品致痫大鼠各期海马中Toll-样受体9(TLR9)、髓样分化因子(MyD88)表达的变化,探讨其是否与颞叶癫痫发生有关。方法 SD雄性大鼠120只,随机分为对照组(30只)和模型组(90只),腹腔注射氯化锂。18 h~20 h后模型组腹腔注射匹罗卡品诱导癫痫持续状态(SE);对照组予等量生理盐水取代匹罗卡品腹腔注射。对照组和造模成功的模型组依据腹腔注射后时间随机分为10个亚组:急性模型组(SE后3 h、6 h、9 h、12 h、1 d、3 d、7 d);潜伏模型组(SE后14 d、28 d);慢自发发作组(SE后56 d)。每亚组动物模型组9只,对照组3只。免疫组化、蛋白印迹、RT-PCR技术测定各亚组癫痫大鼠海马内TLR9、MyD88的表达。结果TLR9、MyD88在模型组海马内表达明显增多,与对照组相比,差异有显著性(P0.05)。模型亚组内,TLR9、MyD88在急性期和慢性期表达明显增高,而潜伏期无明显表达变化。其中急性期内的增高多集中在癫痫发作后6 h;3组比较差异有显著性(P0.05)。结论大鼠海马内TLR9、MyD88表达增多可能与颞叶癫痫发病有关,探讨其机制可能为颞叶癫痫的治疗提供新的靶点。     

锂-匹罗卡品致痫大鼠海马胶质纤维酸性蛋白的表达及意义

目的观察其海马经HE染色后组织病理学、胶质纤维酸性蛋白免疫反应阳性表达细胞在LPS中各观察时间点海马CA1、CA3、齿状回的表达,探讨其致机制。方法锂-匹罗卡品急性诱导SD癫痫持续状态模型鼠形成后,采用免疫组化和图像分析方法观察海马HE染色组织病理学、胶质纤维酸性蛋白免疫反应阳性表达细胞。结果模型组各时间点海马细胞形态出现病理性改变,部分细胞脱失,胞浆浓缩,胞核固缩深染;胶质纤维酸性蛋白免疫反应阳性表达细胞亦显著上调（P〈0.05）。结论Pilo诱导SD大鼠癫痫发作后存在显著的海马神经元结构和胶质细胞的损伤,以胶质细胞损伤更显著,胶质纤维酸性蛋白持续高表达可能是这种功能异常的胶质细胞增生的重要原因,也可能是锂-匹罗卡品致癫痫发作的重要因素之一。     

氯化锂-匹罗卡品致痫幼鼠脑内c-jun和c-fos蛋白的表达

目的 探讨幼鼠癫痫持续状态(SE)后脑内c-jun和c-fos蛋白的表达。方法 采用氯化锂-匹罗卡品腹腔注射制成幼鼠SE模型。应用免疫组化及常规病理检查方法观察c-jun和c-fos蛋白的表达。结果 注射匹罗卡品1h后在海马结构和大脑皮质的大部分区域出现少量的c-jun和c-fos免疫反应阳性细胞，3～6h强烈表达，并达到高峰，24h后明显减弱，72h近乎正常对照水平。地西泮干预组幼鼠脑内有少量的c-jun和c-fos免疫反应阳性细胞，略多于生理盐水对照组。海马结构区的c-jun和c-fos免疫反应阳性细胞明显高于皮质区。SE组幼鼠的CA1、CA3和齿状回区可见到许多神经元发生变性和坏死。结论 c-jun和c-fos蛋白表达及其表达程度与SE后脑损伤的部位和分布有关；地西泮有对抗匹罗卡品致病作用，可能对脑组织有保护作用。     

代谢型谷氨酸受体亚型1基因在锂一匹罗卡品致痫大鼠齿状回中的长期高表达

目的：观察锂一匹罗卡品诱导的癫痫大鼠模型海马结构中代谢型谷氨酸受体亚型1(mGluRl)mRNA的动态表达变化。方法：用地高辛标记的多相寡核苷酸探针通过原位杂交方法检测海马各个区域在7d、14d和28d时mGluRlmRNA的表达。结果：在上述3个时间点齿状回mGluR1mRNA的表达明显上调，而在海马CAl区仅7d时可见mGluRlmRNA的相对上调，其余时间点无明显变化。结论：本研究提示锂一匹罗卡品癫痫模型齿状回mGluRlmRNA表达长期上调可能与海马结构的重塑和癫痫易感性形成有关。     

Effects of Low‐Frequency Hippocampal Stimulation on Gamma‐Amino Butyric Acid Type B Receptor Expression in Pharmacoresistant Amygdaloid Kindling Epileptic Rats

Objective: To observe the effect of low‐frequency hippocampal stimulation on gamma‐amino butyric acid type B (GABA‐B) receptor expression in hippocampus pharmacoresistant epileptic rats. Materials and Methods: Sixteen pharmacoresistant epileptic rats were selected by testing their seizure response to phenytoin and phenobarbital, and they were randomly divided into a pharmacoresistant control group (PRC group, eight rats) and a pharmacoresistant stimulation group (PRS group, eight rats). Another 16 pharmacosensitive epileptic rats were served as control, also divided randomly into a pharmacosensitive control group (PSC group) and a pharmacosensitive stimulation group (PSS group). A stimulation electrode was implanted into the rats' hippocampus in the four groups. Low‐frequency hippocampal stimulation was administered twice per day for two weeks. Following these weeks of stimulation, GABA‐B receptor‐positive neurons were counted and the gray values of GABA‐B receptor expression in the rats' hippocampal tissues were measured. Results: The amygdale stimulus‐induced epileptic seizures were decreased significantly in the PRS group compared with the PRC group. The parameters of the amygdale after discharge also were improved after hippocampal stimulation. Simultaneously, the GABA‐B receptor‐positive neurons increased and the GABA‐B expression gray values decreased markedly in the PRS group compared with the PRC group. The same phenomenon also was observed between the PSS group and the PSC group. However, no significant difference was found in the GABA‐B receptor‐positive neurons and the gray values of GABA‐B between the PRS group and the PSC group. Conclusions: The low‐frequency hippocampal stimulation may inhibit the amygdale stimulus‐induced epileptic seizures and the after discharges. The antiepileptic effects of the hippocampal stimulation may be achieved partly by increasing the expression of the GABA‐B receptor.     

米诺环素对癫痫大鼠海马小胶质细胞的抑制作用

目的探讨米诺环素对癫痫大鼠海马小胶质细胞的抑制作用。 方法将40只雄性SD大鼠按随机数字表法分为4组：生理盐水组、青霉素组、米诺环素治疗组和米诺环素预处理组,每组各10只。大鼠腹腔注射青霉素G 740万～760万单位/kg以建立大鼠癫痫模型。免疫荧光组织化学技术检测大鼠造模后第1、3天海马小胶质细胞免疫反应性,Western blotting检测海马肿瘤生长因子-α(TNF-α)蛋白表达情况。 结果(1)癫痫发作可激活小胶质细胞。与青霉素组比较,大鼠癫痫发作后第1、3天米诺环素治疗组、米诺环素预处理组海马小胶质细胞活化、增生受抑制,差异均有统计学意义（P≤0.05）,且米诺环素预处理组抑制性更突出。(2)大鼠癫痫发作后第1、3天青霉索组、米诺环素治疗组、米诺环素预处理组TNF-α蛋白表达水平明显高于生理盐水组,差异均有统计学意义(P≤0.05);与青霉素组比较,米诺环素治疗组、米诺环素预处理组TNF-α蛋白表达水平降低,差异均有统计学意义(P≤0.05),且以米诺环素预处理组更明显。 结论米诺环素可有效抑制癫痫大鼠海马小胶质细胞活化、增生和炎症因子TNF-α的释放。     

SNL大鼠L5 脊髓背角c-Fos的表达与谷氨酸不同投入途径的关系

1. We examined the effects of L-Glutamic acid (Glu), a NMDA receptor antagonist, D-2-amino-5-phosphonopentanoate (D-AP5) as well as a selective Group I mGluR antagonist, 7-Hydroyiminocyclo propan[a]chromen-1a- carboxylic acid ethyl ester (cpccoEt ), on c-fos-like immunoreactivity (c-fos LI) within the L5 spinal cord dorsal horn of urethane anaesthetized Sprague-Dawley rats, in which L5-L6 nerves were ligated to produce neuropathic pain model (SNL model), two weeks after the operation, rats were adopted. 2. In SNL rats, nerve ligation with no drug use resulted in an increase in the level of c-Fos expression in two sides of spinal cord, particularly, in III/IV of ligated side. Intraplantar or intrathecal administration of saline significantly increased the c-Fos labeled neurons in I/II of ligated side compared with ligated group without saline administration, there was no difference between intraplantar and intrathecal administration of saline in I/II of ligated side. 3. On the other hand, either intraplantar or intrathecal administration, glutamate (5 mol) could significantly increase the number of c-Fos positive neurons compared with saline group value in intact, sham-operated and SNL rats; when intrathecal administration of glutamate into SNL rats, the number of c-Fos positive neurons in I/II of ligated side was three times higher than that induced by intraplantar administration; however, there was no difference between in I/II of ligated and of unligated side in the level of c-Fos expression induced by intrathecal administration. In addition, the number of c-Fos positive neurons in I/II of ligated side induced by intrathecal administration of glutamate in SNL rats was two times higher than in sham-operated rats. 4. There was no difference among saline group, D-AP5 (50 nmol) group and cpccoEt (250 nmol) group in the number of c-fos LI cells either in sham-operated or in SNL rats, respectively; In addition, the number of c-Fos positive neurons in I/II ipisilateral side induced by saline or D-AP5 in SNL rats was three times higher than that in sham-operated rats, by cpccoEt in SNL rats was two times higher than that in sham-operated rats. However, glutamate (5 mol) combined with D-AP5 (50 nmol) or cpccoEt (250 nmol), intrathecal administration, the number of c-Fos positive neurons either in sham-operated or SNL rats was less than glutamate group value, thus, D-AP5 significantly reduced labeled cells in I/II layer induced by glutamate by a maximum of 69.5% in the left side and 72.1% in the right side in sham-operated rats, of 71.6% in ligated side and 70.6% in unligated side, respectively; cpccoEt significantly decreased the number of c-fos LI cells by glutamate by a maximum of 71.8% in the left side and 71.7% in the right side in sham-operated rats, of 72.4% in the ligated side and 90.1% in the unligated side, respectively. 5. Taken together, c-Fos expression may be associated with different pass-way of excitation of nerve. These results suggest that nerve ligation might be able to influence c-Fos expression; saline and glutamate progressively promote the c-Fos expression in SNL rats; blockade of NMDA receptors, group I mGluRs decrease the response of peripheral and spinal cord neurons to glutamate.     

运动训练对新生反复惊厥大鼠发育期海马Zn2+转运体1、谷氨酸受体2表达和认知功能的影响

BACKGROUND： Developmental seizures are pathologically characterized by regenerative sprouting of hippocampal mossy fibers rich in Zn^2＋. Zn^2＋ metabolism in the mossy fiber pathway, and Zn^2＋ accumulation in presynaptic membrane vesicles, are dependent on zinc transporter 1 （ZnT1） and glutamate receptor subunit 2 （GluR2）.
OBJECTIVE： To investigate the effects of long-term recurrent neonatal seizure, in the presence and absence of physical exercise, on the developmental expression of hippocampal zinc transporter 1 （ZnT1） and GluR2, and on cognitive function in rats.
DESIGN, TIME AND SETTING： Based on behavioral examination and molecular biological research, a randomized, controlled animal experiment was performed at the Department of Neurobiology, Medical College of Soochow University, between January 2007 and April 2008.
MATERIALS： Twenty-one 6-day-old Sprague Dawley rats of either gender were employed in this study. ZnT1 mRNA in situ hybridization kit was provided by Tianjin Haoyang Biological Manufacture Co.,Ltd., China. Rabbit anti-GluR2 was purchased from Santa Cruz Biotech, Inc, USA.
METHODS： Rats were randomly divided into a recurrent seizure group （n = 11） and a control group （n = 10）. In the recurrent seizure group, 30-minute seizure was induced by flurothyl gas inhalation for a total of 6 consecutive days. Rats from the control group underwent experimental procedures similar to the recurrent seizure group, with the exception of flurothyl gas inhalation. Thirty minutes of treadmill exercise was performed daily by all rats at postnatal days 51–56.
MAIN OUTCOME MEASURES： At postnatal day 82, rat hippocampal tissue was harvested for analysis of hippocampal ZnT1 and GluR2 expression by in situ hybridization and immunohistochemistry, respectively. Rat learning and memory capabilities were examined using the Y-maze test.
RESULTS： In the recurrent seizure group, the gray scale value of ZnT1 in situ hybridization positive neurons in the hippocampal CA3 region was significantly greater （P 〈 0.05）, while the gray scale value of GluR2 immunoreactive neurons in the hippocampal hilus and dentate gyrus was significantly lower （P 〈 0.05）, than in the control group. At postnatal days 29–35, numbers of trials to criteria for successful learning were greater in the recurrent seizure group than in the control group （P 〈 0.05）; at postnatal days 61–67, the numbers of trials to criteria for successful learning were similar between the two groups （P 〉 0.05）. At postnatal days 29–35 and 61–67, there was no significant difference in memory capability between the recurrent seizure and control groups （P 〉 0.05）.
CONCLUSION： Physical exercise likely improves the learning deficits caused by recurrent neonatal seizure in rats during brain development by modulating ZnT1 and GluR2 expression.     

银杏叶提取物对脑缺血大鼠脑源性神经营养因子的影响

目的　观察银杏叶提取物 (GBE)对局灶脑缺血大鼠脑源性神经营养因子 (BDNF)表达的影响 ,探讨GBE与缺血损伤神经元可塑性的关系。方法　制作大鼠大脑中动脉闭塞 (MCAO)模型 ,应用免疫组化方法观察不同缺血时间 GBE治疗组及脑缺血组 BDNF阳性细胞数 ,并进行图像分析。结果　坏死灶中心区 GBE组及缺血组BDNF阳性神经元均消失 ,但在坏死灶周围区 ,两组 BDNF阳性细胞均显著增加。两组细胞形态无明显不同 ,但GBE治疗组阳性细胞数又显著高于相应缺血对照组。结论　银杏叶提取物可提高大鼠局灶脑缺血半暗带区 BDNF的表达水平 ,促进神经元的修复及重塑。     

Suppression of c-Fos Protein and mRNA Expression in Pentylenetetrazole-Induced Kindled Mouse Brain by Isoxylitones

An early immediate gene c-fos has been proposed as the gene responsible for turning on molecular events that might underlie the long-term neural changes occurring during kindling. We have evaluated the effects of novel anticonvulsant isomeric compounds isoxylitones [(E/Z)-2-propanone-1,3,5,5-trimethyl-2-cyclohexen-1-ylidine] on the c-Fos protein and mRNA expression in the brain samples of kindled mice and compared it with the normal and untreated kindled groups. Kindling was induced in male NMRI mice by repeated administration of sub-convulsive dose (50 mg/kg) of pentylenetetrazole (PTZ) until a seizure score of 4-5 was achieved. The c-Fos expression was quantified by combination of immunohistochemistry and RT-PCR protocols. Both the immunohistochemical and RT-PCR analysis revealed a marked increase in the expression of c-fos mRNA and protein in the brain regions tested in case of PTZ-kindled control group compared to normal control. In contrast, the isoxylitone (30 mg/kg)-treated group demonstrated significant reduction of c-Fos expression compared to PTZ-kindled control animals. However, low expression of c-fos mRNA was only detected in the thalamus of the isoxylitone-treated brain samples. Based on these observations, we suggest that isoxylitones may have the capacity to control the seizure pattern by mechanism such as the suppression of c-Fos protein and mRNA levels in different regions of the brain. Further investigations to explore the mechanism of action of these compounds are under process.     

Suppression by intrathecal BmK IT2 on rat spontaneous pain behaviors and spinal c-Fos expression induced by formalin

The central anti-nociception of BmK IT2, a sodium channel modulator from scorpion Buthus martensi Karsh (BmK) was investigated in this study. It was found that the formalin-induced rat spontaneous flinches and spinal c-Fos expression could be significantly suppressed by intrathecal BmK IT2 pre- or post-formalin injection in a dose-dependent manner. The time course of inhibitory effect exerted by intrathecal BmK IT2 on spontaneous flinches was longer in the pre-treatment group than in post-treatment group. This was consistent with the stronger suppression on spinal c-Fos expression exerted by intrathecal BmK IT2 pre-treatment. In addition, the suppression by intrathecal BmK IT2 on formalin-induced c-Fos expression in superficial laminae was more significant than that in deeper laminae. These results indicate that BmK IT2 can induce central anti-nociceptive response and might thus be a valuable molecular tool for the understanding of pain mechanisms.     

Effects of antiepileptic drugs on induced epileptiform activity in a rat model of dysplasia

Seizure activity associated with cortical dysplasia (CD) is often resistant to standard pharmacologic treatments. Although several animal models exhibit CD, virtually nothing is known about antiepileptic drug (AED) responses in these animals. Here we have used rats exposed to methylazoxymethanol acetate (MAM) in utero, an animal model featuring nodular heterotopia, to investigate the effects of AEDs in the dysplastic brain. 4-aminopyridine (100 μM), a K⁺ channel blocker, was used to induce interictal epileptiform bursting in acute hippocampal slices from MAM-exposed and age-matched vehicle-injected control animals. Extracellular field recordings were used to monitor seizure activity in vitro. Five commonly used AEDs were tested: phenobarbital, 25–400 μM; carbamazepine, 25–200 μM; valproate (VPA), 0.19–4 mM; ethosuximide (ESM), 0.5–8 mM; and lamotrigine (LTG), 49–390 μM. 4-AP-induced bursting occurred with shorter latencies in slices from MAM-exposed rats in comparison with slices from controls, confirming the intrinsic hyperexcitability of dysplastic tissue. Each AED tested demonstrated significant burst suppression in control slices, but interictal epileptiform bursting in MAM-exposed slices was resistant to these treatments. Even at the highest concentrations, VPA, ESM and LTG had no effect on burst amplitude in slices from MAM-exposed rats. Pharmaco-resistance was further tested by measuring seizure latencies in awake, freely-moving rats after kainate administration (15 mg/kg, i.p.) with and without pre-treatment with VPA (400 mg/kg i.p.). Pre-treatment with VPA prolonged seizure latency in control rats, but had no effect in MAM-exposed animals. These results suggest MAM-exposed rats exhibit a dramatically reduced sensitivity to commonly prescribed AEDs.     

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。     

Continuous local intrahippocampal delivery of adenosine reduces seizure frequency in rats with spontaneous seizures

Purpose: Despite different treatment options for patients with refractory epilepsy such as epilepsy surgery and neurostimulation, many patients still have seizures and/or drug‐related cerebral and systemic side effects. Local intracerebral delivery of antiepileptic compounds may represent a novel strategy with specific advantages such as the option of higher local doses and reduced side effects. In this study we evaluate the antiepileptic effect of local delivery of adenosine in the kainic acid rat model, a validated model for temporal lobe epilepsy. Methods: Fifteen rats, in which intraperitoneal kainic acid injection had induced spontaneous seizures, were implanted with a combination of depth electrodes and a cannula in both hippocampi. Cannulas were connected to osmotic minipumps to allow continuous hippocampal delivery. Rats were freely moving and permanently monitored by video‐EEG (electroencephalography). Seizures were scored during 2 weeks of local hippocampal delivery of saline (baseline), followed by 2 weeks of local adenosine (6 mg/ml) (n = 10) or saline (n = 5) delivery (0.23 μl/h) (treatment). In 7 of 10 adenosine‐treated rats, saline was also delivered during a washout period. Results: During the treatment period a mean daily seizure frequency reduction of 33% compared to the baseline rate was found in adenosine‐treated rats (p < 0.01). Four rats had a seizure frequency reduction of at least 50%. Both nonconvulsive and convulsive seizures significantly decreased during the treatment period. In the saline‐control group, mean daily seizure frequency increased with 35% during the treatment period. Conclusions: This study demonstrates the antiseizure effect of continuous adenosine delivery in the hippocampi in rats with spontaneous seizures.