Orexin受体拮抗剂对睡眠剥夺的戊四氮致(癎)大鼠癫(癎)发作及脑组织病理学变化的影响

目的 探讨orexin-1受体(OX1R)和orexin-2受体(OX2R)拮抗剂对睡眠剥夺(SD)的戊四氮(PTZ)致(癎)大鼠癫(癎)发作及脑组织病理学变化的影响.方法 雄性Wistar大鼠48只,随机分为正常对照(NC)组、PTZ组、SD+ PTZ( SD)组、SD+ PTZ+二甲基亚砜(DMSO)组、SD+ PTZ+ OX1R拮抗剂SB334867(SB)组和SD+ PTZ+ OX2R拮抗剂TCS OX229 (TCS)组.采用改良多平台SD法,SD前及SD 48 h分别给予相应组大鼠侧脑室注射DMSO、SB或TCS.SD 72 h给予各组腹腔注射PTZ 50 mg/kg诱导癫(癎)发作;观察各组大鼠癫(癎)发作的潜伏期、发作等级评分、发作持续时间及死亡率;应用常规染色法观察海马的病理学变化,免疫荧光法(BrdU标记)观察神经细胞增殖的变化.结果 (1)与PTZ组比较,SD组及DMSO组(癎)性发作的潜伏期明显缩短,发作等级评分、持续时间及死亡率明显增加(均P ＜0.001),海马CA3区神经元损害加重,海马齿状回门区和颗粒细胞下层BrdU阳性细胞数显著增多(P＜0.001);SD组与DMSO组间差异无统计学意义.(2)与SD组比较,SB组和TCS组大鼠(癎)性发作的潜伏期明显延长,发作等级评分、持续时间及死亡率明显下降(均P＜0.05),海马CA3区神经元损害明显减轻,齿状回门区和颗粒下层BrdU阳性细胞数减少(均P ＜0.05);TCS组的变化较SB组更显著(P＜0.05 ～0.01).结论 Orexin受体拮抗剂尤其是OX2R拮抗剂可通过减轻海马CA3区神经元的损害和抑制齿状回区细胞增殖减轻SD对PTZ诱导癫(癎)发作的不利影响.     

养血清脑颗粒和丙戊酸联用对戊四氮点燃癫痫大鼠的影响

目的 探讨养血清脑颗粒(YXQNG)联用丙戊酸(VPA)对戊四氮(PTZ)慢性点燃模型大鼠癫痫发作、EEG、认知功能及颞叶、海马T型Ca2+通道蛋白(Cav3.2)表达的影响. 方法 成年雄性SD大鼠40只按随机数字表法分为PTZ组、VPA组、VPA+YXQNG组、NS组,每组10只.前3组大鼠腹腔注射PTZ溶液制作慢性点燃模型,VPA组大鼠在注射PTZ前1 h给予VPA灌胃;VPA+YXQNG组除给予VPA外,注射PTZ前1.5 h给予YXQNG灌胃;NS组腹腔注射生理盐水,每天一次.8周后观察各组大鼠的行为学变化、Y型电迷宫检查大鼠的正确反应率、捕记EEG并应用免疫组化染色检测颞叶和海马Cav3.2的表达. 结果 给药8周后PTZ组大鼠全部达到完全点燃(连续3 d出现Ⅳ级发作或达到Ⅴ级发作),VPA组和VPA+YXQNG组大鼠仅出现0～Ⅱ级发作;Y型电迷宫检查结果显示VPA+YXQNG组大鼠正确反应率高于PTZ组,差异有统计学意义(P＜0.05);EEG结果显示PTZ组大鼠癫痫发作时EEG有明显异常放电,总功率高于用药前,差异有统计学意义(P＜0.05).VPA组、VPA+YXQNG组大鼠用药前后EEG总功率的差值均高于PTZ组,差异有统计学意义(P＜0.05);免疫组化染色结果显示VPA组、VPA+YXQNG组大鼠颞叶和海马Cav3.2表达低于PTZ组,VPA+YXQNG组大鼠颞叶和海马Cav3.2表达低于VPA组,差异均有统计学意义(P＜0.05). 结论 YXQNG和VPA联用能降低癫痫大鼠发作级别、改善认知功能、减少脑部异常放电并降低脑组织Cav3.2水平,有抗癫痫和脑保护作用.

Abstract：

Objective To explore the effet of Yangxue Qingnao granule (YXQNG) on seizures and cognition function of pentylenetetrazole (PTZ)-kindled chronic epileptic rats models, expression of Cav3.2 in the hippocampus and the temporal lobe of these rats, and EEG features of the rats. Methods Forty healthy adult male SD rats were equally divided into 4 groups at random: PTZ group, VPA treatment group, VPA+YXQNG treatment group, normal saline (NS)-control group (n=10). PTZ solution was intraperitoneally injected for 8 weeks to induce the kindling model in the above 3 groups except the NS-control group. VPA by intragastric administration was given to the rats in the VPA treatment group 1 h before PTZ injection; YXQNG and VPA by intragastric administration were given to the rats in the VPA+YXQNG treatment group 1.5 h before PTZ injection. Behavioral changes of the rats were observed 8 weeks after PTZ injection; accuracy rate of response of the rats were examined by electric maze test;EEG was performed; and the expression ofT-type Ca2+ channel protein (Cav3.2) in the temporal lobe and hippocampus was detected by immunohistochemical staining. Results Rats in the PTZ group appeared grade Ⅳ or Ⅴ seizures for 3 consecutive d, and rats in the VPA treatment group, VPA+YXQNG treatment group appeared grade 0-Ⅱ seizures. The accuracy rate of response of the rats in the VPA+YXQNG treatment group was significantly higher than that in the PTZ group (P＜0.05). EEG indicated that paradoxical discharge was noted in rats of PTZ group when seizures appeared, and the total power at the time was obviously higher than that before PTZ injection (P＜0.05). The D-value of total power of EEG in rats of the VPA treatment group and VPA+YXQNG treatment group before and after treatment was significantly higher than that in the PTZ group (P＜0.05). And the level of Cav3.2 in the temporal and hippocampus in rats of the VPA treatment group and VPA+YXQNG treatment group was significantly lower than that in the PTZ group (P＜0.05); as compared with that in the VPA treatment group, the expression of Cav3.2 in the temporal and hippocampus in rats of the VPA+YXQNG treatment group was significantly reduced (P＜0.05). Conclusion The combination use of YXQNG and VPA can decrease the seizure stage, the paradoxical discharge of the brain and the level of Cav3.2 in brain tissue,and improve the cognitive function of the PTZ-kindled rats, indicating that using VAP and YXQNG simultaneously can treat epileptic seizure and protect the neurons.     

雷帕霉素干预对左旋多巴诱发的异动症大鼠行为学的影响

目的研究雷帕霉素干预对左旋多巴诱发的异动症(LID)的行为学的影响。方法通过6-羟基多巴胺颅内立体定向注射制作偏侧大鼠帕金森病模型。给予左旋多巴腹腔注射1周制作LID大鼠模型。将LID大鼠分为LID对照组(LID组)和雷帕霉素干预观察组(RAPA组)。继续左旋多巴腹腔注射2周,RAPA组大鼠每天于左旋多巴注射前45 min腹腔注射雷帕霉素,低剂量0.25 mg/(kg·d)、中剂量0.35mg/(kg·d)、高剂量0.5 mg/(kg·d),每周注射4 d,持续2周。对照组同时给予等体积生理盐水腹腔注射。记录大鼠异常不自主运动(AIM)评分并对比分析。结果 RAPA低剂量亚组未观察到有意义的行为学改变;RAPA高剂量亚组在雷帕霉素给药后数天出现精神萎靡、食欲减退、血尿等症状,5~10 d左右逐渐死亡,经尸体解剖及病理切片发现,动物死亡原因与肺炎、肝肾损害等原因密切相关。RAPA中剂量亚组行为学改变比较理想,且动物耐受性较好,没有出现死亡。RAPA干预治疗开始起,RAPA中剂量亚组大鼠每天AIM评分均较LID组大鼠明显降低(均P0.05)。左旋多巴注射第20 d,RAPA中剂量亚组大鼠左旋多巴治疗后120 min内AIM评分均较LID组大鼠明显降低(均P0.05)。结论雷帕霉素治疗能显著改善LID大鼠行为学表现,改善LID大鼠不自主运动症状。     

Orexin受体拮抗剂对睡眠剥夺的戊四氮致疒间大鼠癫疒间发作及脑组织病理学变化的影响

目的探讨orexin-1受体(OX1R)和orexin-2受体(OX2R)拮抗剂对睡眠剥夺(SD)的戊四氮(PTZ)致疒间大鼠癫疒间发作及脑组织病理学变化的影响。方法雄性Wistar大鼠48只,随机分为正常对照(NC)组、PTZ组、SD+PTZ(SD)组、SD+PTZ+二甲基亚砜(DMSO)组、SD+PTZ+OX1R拮抗剂SB334867(SB)组和SD+PTZ+OX2R拮抗剂TCS OX229(TCS)组。采用改良多平台SD法,SD前及SD 48 h分别给予相应组大鼠侧脑室注射DMSO、SB或TCS。SD 72 h给予各组腹腔注射PTZ 50 mg/kg诱导癫疒间发作;观察各组大鼠癫疒间发作的潜伏期、发作等级评分、发作持续时间及死亡率;应用常规染色法观察海马的病理学变化,免疫荧光法(BrdU标记)观察神经细胞增殖的变化。结果 (1)与PTZ组比较,SD组及DMSO组疒间性发作的潜伏期明显缩短,发作等级评分、持续时间及死亡率明显增加(均P<0.001),海马CA3区神经元损害加重,海马齿状回门区和颗粒细胞下层BrdU阳性细胞数显著增多(P<0.001);SD组与DMSO组间差异无统计学意义。(2)与SD组比较...     

激光氧液对癫持续状态大鼠海马组织MDA、SOD动态变化的影响及疗程选择

目的观察激光氧液对戊四氮(PTZ)所致癫持续状态(SE)大鼠海马组织丙二醛(MDA)和超氧化物歧化酶(SOD)的影响及激光氧液的疗程选择。方法 28日龄雄性SD大鼠以PTZ建立癫持续状态模型,随机分为PTZ+激光氧液组、PTZ+GS组和NS+激光氧液组、NS+GS组,分别给予激光氧液和5%葡萄糖液(5%GS)尾静脉输入,于模型制作成功后第0、3、7、10、14天采用比色法检测MDA含量和SOD活力。结果 (1)MDA结果:PTZ+GS组大鼠海马组织MDA含量在SE后3d、7d、10d、14d较NS+GS组明显增高(P0.05),PTZ+激光氧液组与之趋势相同,但在各时间点均较PTZ+GS组大鼠降低(P0.05)。(2)SOD结果:PTZ+GS组大鼠海马组织SOD活力在SE后3d、7d较NS+GS组明显降低(P0.05),PTZ+激光氧液组SOD活力与之趋势相同,但在3d、7d、10d三个时间点上较PTZ+GS组大鼠升高(P0.05)。第14天各组大鼠海马内SOD活力均无统计学差异(P0.05)。结论 (1)激光氧液能降低SE大鼠MDA含量,升高SOD活力。(2)激光氧液的治疗可选择10d为一疗程。     

ERK1/2激活物Orexin-A对癫痫大鼠学习记忆及海马神经细胞增殖的影响

目的探讨ERK1/2激活物orexin-A(OXA)对戊四氮(PTZ)点燃大鼠空间学习记忆功能及海马齿状回神经细胞增殖的影响。方法 60只大鼠随机分为对照组、PTZ+生理盐水(NS)组、PTZ+OXA组、PTZ+U0126组和PTZ+U0126+OXA组,每组12只。采用腹腔注射PTZ(35 mg/kg)制模。制模后,对照组及PTZ+NS组大鼠注射8μl生理盐水,PTZ+OXA组大鼠注射8μl OXA,PTZ+U0126组注射8μl U0126,PTZ+U0126+OXA组注射8μl U0126和OXA 8μl。通过Morris水迷宫试验观察各组大鼠的空间学习记忆能力,并用BrdU腹腔注射和免疫荧光共聚焦技术检测海马齿状回区BrdU和BrdU/双皮质素(DCX)的阳性表达。结果 PTZ+NS组、PTZ+OXA组、PTZ+U0126组、PTZ+U0126+OXA组大鼠逃避潜伏期显著长于对照组(均P0.01)。PTZ+NS组、PTZ+U0126组及PTZ+U0126+OXA组大鼠逃避潜伏期显著长于PTZ+OXA组(P0.05~0.01)。与PTZ+NS组比较,PTZ+OXA组、PTZ+U0126+OXA组大鼠穿越平台象限的次数增加,平台所在象限的游泳时间延长(均P0.01);而PTZ+U0126组大鼠穿越平台象限的次数及平台所在象限的游泳时间均减少(均P0.01)。PTZ+U0126+OXA组大鼠穿越平台象限的次数显著少于、平台所在象限的游泳时间短于PTZ+OXA组(均P0.01)。PTZ+NS组、PTZ+U0126组及PTZ+U0126+OXA组大鼠海马齿状回区BrdU+/DCX+细胞数少于PTZ+OXA组(P0.05~0.01)。结论 OXA可通过促进齿状回颗粒细胞的再生改善癫痫大鼠的空间学习记忆能力,这可能与ERK1/2激活有关。     

激光氧液对癫(癎)持续状态大鼠海马组织MDA、SOD动态变化的影响及疗程选择

目的 观察激光氧液对戊四氮(PTZ)所致癫(癎)持续状态(SE)大鼠海马组织丙二醛(MDA)和超氧化物歧化酶(SOD)的影响及激光氧液的疗程选择.方法 28日龄雄性SD大鼠以PTZ建立癫(癎)持续状态模型,随机分为PTZ+激光氧液组、PTZ+GS组和NS+激光氧液组、NS+GS组,分别给予激光氧液和5％葡萄糖液(5％GS)尾静脉输入,于模型制作成功后第0、3、7、10、14天采用比色法检测MDA含量和SOD活力.结果 (1)MDA结果:PTZ+ GS组大鼠海马组织MDA含量在SE后3d、7d、10 d、14 d较NS+ GS组明显增高(P＜0.05),PTZ+激光氧液组与之趋势相同,但在各时间点均较PTZ+GS组大鼠降低(P＜0.05).(2)SOD结果:PTZ+ GS组大鼠海马组织SOD活力在SE后3d、7d较NS+GS组明显降低(P＜0.05),PTZ+激光氧液组SOD活力与之趋势相同,但在3d、7d、10d三个时间点上较PTZ+ GS组大鼠升高(P＜0.05).第14天各组大鼠海马内SOD活力均无统计学差异(P＞0.05).结论 (1)激光氧液能降低SE大鼠MDA含量,升高SOD活力.(2)激光氧液的治疗可选择10 d为一疗程.     

戊四氮致痫大鼠海马GSK-3β表达与苔藓纤维出芽关系研究

目的观察戊四氮(PTZ)致痫大鼠海马各区糖原合成酶激酶-3β(GSK-3β)蛋白及其mRNA表达和苔藓纤维出芽(MFS)情况,探讨GSK-3β在癫痫发病机制中的作用。方法SD雄性成年大鼠120只,随机分为实验组和对照组;实验组分为PTZ第1次注射后3d、1w、2w、4w、6w共5个亚组,每亚组12只。对照组同样随机分为5个亚组,每亚组12只,与实验组各时间点对应。以上各亚组再分2个小组,每小组6只大鼠,分别进行(1)GSK-3β的免疫组化和原位杂交染色并测定其相应的光密度值;(2)Timm染色并评分。结果实验组大鼠海马各区GSK-3β蛋白及其mRNA表达在点燃过程中逐渐增多,点燃后表达逐渐下调到正常对照组水平,在点燃前后除6w组外GSK-3β表达与对照组相应时间点比较差异有统计学意义(P<0.05);实验组CA3区在点燃前可见1~4级MFS,点燃后可见4~5级MFS;癫痫点燃过程中CA3区GSK-3β表达与MFS评分有线性正相关关系。结论GSK-3β在海马表达变化可能在苔藓纤维出芽的过程中起促进作用,从而促进癫痫的发生。     

柴胡总皂甙对戊四氮慢性点燃大鼠海马谷氨酸细胞的影响

目的研究柴胡总皂甙对戊四氮(PTZ)慢性点燃癫痫模型大鼠海马区谷氨酸(Glu)阳性细胞表达的影响。方法48只健康SD大鼠被随机分为6组,即空白组(A组)、生理盐水组(B组)、丙戊酸钠(VPA)组(C组)和柴胡总皂甙高、中、低三种剂量组(D组、E组、F组),每组8只,除A组不做处理外,其他各组采用腹腔注射PTZ慢性点燃造模,造模同时给予VPA、柴胡总皂甙等不同处理因素,连续4周后取脑组织切片进行Glu免疫组化染色,从阳性细胞数、灰度值分析结果。结果在CAl区,B组海马阳性细胞数高于A、C、D、E、F组,有显著性差异(P＜0．05),B组海马各区阳性细胞灰度值低于其他各组,与A、C、D各组比较,有显著性差异(P＜0．05)；而在CA2区和DG区,B组阳性细胞数、灰度值与各组差异无统计学意义。结论柴胡总皂甙可以影响PTZ点燃大鼠海马CA1区的Glu表达水平,从而抑制PTZ慢性点燃大鼠的痫性发作。     

Caspase-9在戊四氮所致癫痫持续状态大鼠神经元中的表达及重组人红细胞生成素的影响

目的观察重组人红细胞生成素(r Hu EPO)对戊四氮(PTZ)点燃的癫痫持续状态(SE)的SD大鼠海马神经元的影响,应用磷脂酰肌醇3激酶(PI3K)抑制剂LY294002,观察门冬氨酸特异半胱氨酸蛋白酶-9(Caspase-9)的变化情况,为r Hu EPO在癫痫诊疗中提供实验室依据。方法采用PTZ点燃大鼠SE模型,将大鼠随机分为正常对照组(生理盐水,NS)、PTZ组(PTZ+NS)、r Hu EPO组(PTZ+r Hu EPO)、LY294002组(PTZ+LY294002+r Hu EPO)、二甲基亚砜(DMSO)对照组(PTZ+DMSO+r Hu EPO),检测各组大鼠行为学和脑电图(EEG)的改变;TUNEL法检测海马神经细胞的凋亡情况;免疫组织化学法观察磷酸化蛋白激酶B(p-PKB/p-Akt)、Caspase-9的表达;反转录多聚酶链反应(RT-PCR)方法检测各组大鼠海马Caspase-9m RNA的表达,Western blot方法检测各组大鼠海马Akt、p-Akt、Caspase-9蛋白的表达。结果r Hu EPO可以下调Caspase-9的表达,发挥神经保护作用;加入PI3K抑制剂LY294002,海马Caspase-9蛋白、Caspase-9m RNA的表达较r Hu EPO组增加,减弱了r Hu EPO的保护作用(P0.05)。结论 r Hu EPO在癫痫持续状态所致损伤中具有神经保护作用,应用PI3K/Akt抑制剂进一步佐证了该作用可能是通过了PI3K/Akt信号通路,通过对线粒体凋亡途径的相关调控因子Caspase-9的表达进行调控,发挥抗凋亡、促存活的神经保护作用。     

Long-lasting effects of partial hippocampal kindling on hippocampal physiology and function

The objective of this project was to study the behavioral and physiological effects at 6–9 weeks after evoking 15 afterdischarges (ADs) in hippocampal CA1 (partial hippocampal kindling). Rats were trained on the open radial arm maze (RAM) with all eight arms baited, kindled, and then tested again on the RAM, followed by in vitro recordings at 8–9 weeks after kindling. Partial kindling was manifested by an increase in hippocampal AD duration. Enhancement of the commissural basal dendritic excitatory postsynaptic potential (EPSP) was observed for at least 1 day after the ADs kindled rats performed worse than control rats during the 1st but not during the 7th or 8th week after kindling. Rats that were slow in acquiring the RAM showed more RAM errors after kindling than those that showed fast acquisition. At 8–9 weeks after kindling, as shown by field potential recording in the hippocampal slice in vitro, kindled rats showed an increase in paired-pulse facilitation (PPF) of the EPSP in CA1 but a decreased PPF of the perforant path to dentate gyrus EPSP; no change in the PPF of the population spike was found in CA1 or DG. In a second group of rats that were not run on the RAM, at 6 weeks after kindling, PPF of the population EPSP and population spike were enhanced in the kindled rats compared to the control rats in CA1, but not in DG or CA3 in vitro (at 1.5, 2, or 4 times threshold intensity). In conclusion, partial hippocampal kindling induced persistent physiological effects for up to 8–9 weeks, and it is suggested that the normalization of the paired-pulse population spike response in CA1 and DG at more than 6 weeks after kindling may be accompanied by a recovery of RAM performance. © 1994 Wiley-Liss, Inc.     

戊四氮点燃模型大鼠Cdk5活性与苔藓纤维出芽相关性

目的研究戊四氮(PTZ)点燃模型大鼠细胞周期素依赖性激酶5(Cdk5)活性改变与苔藓纤维出芽(MFS)动态变化的相关性。方法将120只雄性成年大鼠随机分为PTZ组和对照组,PTZ组连续每天腹腔注射PTZ30mg/kg,对照组同时注射等体积生理盐水。按戊四氮第1次给药后3d、1、2、4和6周各随机分为5个亚组。每个亚组再随机分为2个小组:一组用于液体闪烁计数仪测定各时间点大鼠海马的Cdk5活性;另一组用于Timm染色检测苔藓纤维出芽情况。结果 PTZ组MFS评分3d时增加,2周达高峰并维持至6周;海马Cdk5活性3d时增加,2周达高峰,4周下降,6周恢复对照组水平;较对照组有显著差异。额区Cdk5活性各时间点之间及与对照组之间均无显著性差异。结论 Cdk5可能通过活性增高参与苔藓纤维出芽,从而促使癫发生。     

Neuropathological profile of the pentylenetetrazol (PTZ) kindling model

ABSTRACT

Introduction: There are three phases of seizure developing in pentylenetetrazol (PTZ)-induced kindling animal model: (i) pre-kindling phase; (ii) kindling phase or after animals are fully kindled; (iii) post-kindling phase with non-provoked spontaneous recurrent seizures. The aims of this review were to summarize the progress over time of the electroencephalographic features and neuropathological alterations in kindled PTZ treated animals.

Materials and methods: Keywords relevant to PTZ kindling were used to a guide a literature search on Pubmed, Medline and Cochrane Library.

Results: Clonic seizures induced PTZ at kindling phase led to a strong c-Fos expression in the hippocampus. Although, decline hippocampal neuron and metabolism disturbances were detected at pre-kindlig phase. Repeated PTZ induced seizures alter the GABA-mediated inhibition and glutamate-mediated excitation, which may contribute to increased seizure susceptibility. Similar to chemical animal models such as the pilocarpine and the kainic acid models, mossy fiber sprouting, hippocampal damage, and glucose hypometabolism had been seen after PTZ induced seizures.

Conclusion: PTZ kindling model may improve understanding of the seizures development provided that the differences existing between the phases of kindling model are taken into account.     

Resistance of immature hippocampus to morphologic and physiologic alterations following status epilepticus or kindling.

Seizures in adult rats result in long-term deficits in learning and memory, as well as an enhanced susceptibility to further seizures. In contrast, fewer lasting changes have been found following seizures in rats younger than 20 days old. This age-dependency could be due to differing amounts of hippocampal neuronal damage produced by seizures at different ages. To determine if there is an early developmental resistance to seizure-induced hippocampal damage, we compared the effects of kainic acid (KA)-induced status epilepticus and amygdala kindling on hippocampal dentate gyrus anatomy and electrophysiology, in immature (16 day old) and adult rats. In adult rats, KA status epilepticus resulted in numerous silver-stained degenerating dentate hilar neurons, pyramidal cells in fields CA1 and CA3, and marked numerical reductions in CA3c pyramidal neuron counts (-57%) in separate rats. Two weeks following the last kindled seizure, some, but significantly less, CA3c pyramidal cell loss was observed (-26%). Both KA status epilepticus and kindling in duced mossy-fiber sprouting, as evidenced by ectopic Timm staining in supragranular layers of the dentate gyrus. In hippocampal slices from adult rats, paired-pulse stimulation of perforant path axons revealed a persistent enhancement of dentate granule-cell inhibition following KA status epilepticus or kindling. While seizures induced by KA or kindling in 16-day-old rats were typically more severe than in adults, the immature hippocampus exhibited markedly less KA-induced cell loss (-22%), no kindling-induced loss, no detectable synaptic rearrangement, and no change in dentate inhibition. These results demonstrate that, in immature rats, neither severe KA-induced seizures nor repeated kindled seizures produce the kind of hippocampal damage and changes associated with even less severe seizures in adults. The lesser magnitude of seizure-induced hippocampal alterations in immature rats may explain their greater resistance to long-term effects of seizures on neuronal function, as well as future seizure susceptibility. Conversely, hippocampal neuron loss and altered synaptic physiology in adults may contribute to increased sensitivity to epileptogenic stimuli, spontaneous seizures, and behavioral deficits.     

红藻氨酸致颞叶癫(癎)大鼠脑内Semaphorin3A、Semaphorin4C基因表达的研究

目的研究轴索导向分子Semaphorin3A(Sema3A)、4C(Sema4C)对癫大鼠海马苔藓纤维重建的调控作用及对皮层神经元的保护作用。方法大鼠侧脑室内注射红藻氨酸制备颞叶癫模型,原位杂交法检测致痫间后1d,1、2、3、4周大鼠脑内Sema3A/Sema4C mRNA表达。结果致痫间后1周Sema3A、Sema4CmRNA分别在齿状回(DG),CA3区表达明显下降(P<0.01),持续至3、4周时恢复至正常(P>0.05);致痫间后1d Sema3A mRNA在皮层表达明显下降(P<0.01),持续至1、2周后恢复至正常(P>0.05)。结论红藻氨酸致痫间后DG及CA3区神经元分别下调Sema3A/Sema4C mRNA的表达,促进癫大鼠苔藓纤维重建;皮层神经元通过下调Sema3A mRNA的表达来维持自身存活。     

Pentylenetetrazol seizures increase pro-nerve growth factor-like immunoreactivity in the reticular thalamic nucleus and nerve growth factor mRNA in the dentate gyrus

Neurotrophins may have a neuroprotective role and are probably involved in the control of axonal sprouting and synaptic plasticity. An antibody raised against a pro-sequence of nerve growth factor (NGF) was tested. In control undisturbed rats, a strong immunoreactivity was detected in scattered cells in and around the pyramidal and granule cell layer of the hippocampus and a moderate labeling was found in the reticular thalamic nucleus. In situ hybridization showed specific expression of NGF mRNA in a similar population of scattered cells in the hippocampal formation but not in the reticular thalamic nucleus. Acute epileptic seizures, induced by a convulsive dose of 50 mg/kg pentylenetetrazol (PTZ), strongly in creased NGF mRNA in neurons of the granular layer of the dentate gyrus 3 hr but not 6 hr after the injection. No change in pro-NGF-like immunoreactivity was observed in the hippocampus or reticular thalamic nucleus after acute seizures. Chemical kindling was induced by daily injections of subconvulsive doses (30 mg/kg) of PTZ for 4 weeks. This treatment significantly increased pro-NGF-like immunoreactivity in the reticular thalamic nucleus but did not affect NGF mRNA. These data strengthen a role for the reticular thalamic nucleus and NGF in PTZ kindling. © 1993 Wiley-Liss, Inc.     

Spatial learning deficits and emotional impairments in pentylenetetrazole-kindled rats

Pentylenetetrazole (PTZ) is a chemical kindling agent used to examine the efficacy of potential anticonvulsants in rats. However, the extent to which PTZ mimics postseizure symptoms of epilepsy has not been thoroughly examined. This study assessed whether PTZ-induced seizures produce cognitive and emotional deficits that mimic those observed in many epileptic patients. Rats were given 30mg/kg PTZ or vehicle (intraperitoneally) every other day for 28 days. Those rats exhibiting consistent seizure activity were tested for learning ability and emotional reactivity, beginning 1 week following a single challenge dose of PTZ. Rats given PTZ made more reference memory errors in a radial arm water maze task, and exhibited emotional abnormalities in the forced swim test, the systematic handling test, and the open-field exploratory maze. Histological analysis revealed neuronal loss in the CA1 area and increased mossy fiber sprouting in the dentate gyrus, similar to what is observed in human epilepsy. These results indicate that PTZ kindling provides a useful model of postseizure dysfunction, which can serve as a screen for potential treatments for those cognitive, emotional, and neuropathological deficits that resemble those symptoms observed in human epilepsy.     

Amygdala kindling develops without mossy fiber sprouting and hippocampal neuronal degeneration in rats

Repeated electrical stimulation of limbic structures has been reported to produce the kindling effect together with morphological changes in the hippocampus such as mossy fiber sprouting and/or neuronal loss. However, to argue against a causal role of these neuropathological changes in the development of kindling-associated seizures, we examined mossy fiber sprouting in amygdala (AM)-kindled rats using Timm histochemical staining, and evaluated the hippocampal neuronal degeneration in AM-kindled rats by terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labelling (TUNEL). Amygdala kindling was established by 10.3 +/- 0.7 electrical stimulations, and no increase in Timm granules (neuronal sprouting) was observed up to the time of acquisition of a fully kindled state. However, the density and distribution of Timm granules increased significantly in the dentate gyrus compared with unkindled rats after 29 after-discharges or more than 10 kindled convulsions. In addition, no significant increase in TUNEL-positive cells was found in the hilar polymorphic neurons or in CA3 pyramidal neurons of the kindled rats that had fewer than 29 after-discharges. However, a significant increase of TUNEL-positive cells was found in the granule cell layer in the dentate gyrus of the stimulated side after 18 after-discharges or 10 kindled convulsions. Our result show that AM kindling develops without evidence of mossy fiber sprouting, and that mossy fiber sprouting may appear after repeated kindled convulsions, following death of the granule cells in the dentate gyrus.     

Circuit Mechanisms of Seizures in the Pilocarpine Model of Chronic Epilepsy: Cell Loss and Mossy Fiber Sprouting

We used the pilocarpine model of chronic spontaneous recurrent seizures to evaluate the time course of supragranular dentate sprouting and to assess the relation between several changes that occur in epilep tic tissue with different behavioral manifestations of this experimental model of temporal lobe epilepsy. Pilo carpine-induced status epilepticus (SE) invariably led to cell loss in the hilus of the dentate gyrus (DG) and to spontaneous recurrent seizures. Cell loss was often also noted in the DG and in hippocampal subfields CA1 and CA3. The seizures began to appear at a mean of 15 days after SE induction (silent period), recurred at variable frequencies for each animal, and lasted for as long as the animals were allowed to survive (325 days). The granule cell layer of the DG was dispersed in epileptic animals, and neo-Timm stains showed supra-and intragranular mossy fiber sprouting. Supragranular mossy fiber sprout ing and dentate granule cell dispersion began to appear early after SE (as early as 4 and 9 days, respectively) and reached a plateau by 100 days. Animals with a greater degree of cell loss in hippocampal field CAS showed later onset of chronic epilepsy (r= 0.83, p < 0.0005), suggest ing that CA3 represents one of the routes for seizure spread. These results demonstrate that the pilocarpine model of chronic seizures replicates several of the fea tures of human temporal lobe epilepsy (hippocampal cell loss, suprar and intragranular mossy fiber sprouting, den tate granule cell dispersion, spontaneous recurrent sei zures) and that it may be a useful model for studying this human condition. The results also suggest that even though a certain amount of cell loss in specific areas may be essential for chronic seizures to occur, excessive cell loss may hinder epileptogenesis.