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。     

从癫痫模型大鼠海马神经元中克隆caspase 3的新底物PIAS1

目的从癫痫模型大鼠海马凋亡神经元中克隆caspase-3的新底物.方法制作癫痫模型大鼠海马组织cDNA文库;PCR获得caspase-3的P12和P17两亚基,然后分别定向插入pBridge质粒,构建三杂交诱饵载体;进行酵母三杂交筛库.结果建立成功癫痫模型大鼠海马组织cDNA文库,构建了大鼠caspase-3基因的酵母三杂交诱饵载体,并通过了caspase-3与eIF2α之间的相互作用验证,筛库获得caspase-3的新底物PIAS1.结论用酵母三杂交系统寻找caspase-3下游底物具有可行性,从癫痫模型大鼠海马的cDNA文库中筛库获得caspase-3的新底物PIAS1,为进一步研究caspase-3在癫痫发作引起的海马损伤中的作用奠定了基础.     

海人酸致痫大鼠海马CA3区神经元线粒体超微结构损伤及caspase-3的表达变化

目的观察海人酸(KA)诱导的癫痫持续状态(SE)大鼠海马CA3区神经元线粒体超微结构的损伤及caspase-3的表达变化.方法用KA诱导大鼠SE 2h.于SE终止后第3、12、24小时取海马,电镜观察线粒体的超微结构,免疫组化方法检测caspase-3的表达.腹腔内注射生理盐水的大鼠设为对照组.结果SE终止后3 h,电镜下可见线粒体肿胀及膜完整性的破裂.caspase-3的表达于SE后1 2 h较对照组增加,平均阳性细胞数及灰度值分别为10.49±0.68及45.57±2.27(P＜0.05);于SE后24 h,分别为37 36±0.57及11 5.24±1 22(P＜0.01).结论在实验性SE模型中,海马神经元线粒体超微结构的损伤早于caspase-3的表达,提示线粒体的损伤可能是SE后神经元损伤的关键环节.     

海人藻酸致痫大鼠海马Caspase-3酶活性变化

目的：检测KA致痫后鼠海马Caspase-3酶活性动态变化。方法：运用FIENA法特异性体外检测Caspase-3的活性，结果：KA致痫后6h，鼠海马即有Caspase-3活性显增高，一周内保持高水平，10天开始下降，而正常鼠海马几乎无活性Caspase-3检出。结论：Caspase-3参与癫痫后神经细胞的凋亡损害，特异性Caspase-3酶抑制剂能预防癫痫后凋亡的发生。     

癫痫发作大鼠海马神经元凋亡与caspase-3 mRNA表达的研究

目的 :研究癫大鼠海马神经元凋亡与caspase 3mRNA表达的关系。方法 :采用大鼠红藻氨酸 (KA)致模型 ,以原位末端标记 (TUNEL)检测癫后不同时间海马神经元凋亡 ;RT PCR检测caspase 3mRNA的表达。结果 :KA致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后 6h ,海马组织caspase 3mRNA表达显著增高 ,1、3、7d仍持续高水平表达。结论 :癫大鼠海马神经元凋亡与caspase 3mRNA的表达密切相关 ,caspase 3在神经元凋亡过程中起着重要的作用     

红藻氨酸致惊大鼠海马神经元Caspase—3表达与神经元凋亡

目的：研究Caspase-3在红藻氨酸（Kainate,KA)致惊大鼠海马中的变化及其在海马神经元凋亡中的作用。方法：在KA所致大鼠惊厥模型中，用免疫组织化学方法检测惊厥后不同时间点大鼠海马中Caspase-3的表达，用电子显微镜和原位末端标记法（TUNEL）检测惊厥后不同时间点大鼠海马神经元凋亡。结果：惊厥后1d,大鼠海马内Caspase-3的表达就明显升高，一直持续到惊厥3d；大鼠海马内凋亡细胞从惊厥后3d即明显增多，一直持续到惊厥后7d。结论：KA所致惊厥后，大鼠海马内Caspase-3表达明显升高，神经元凋亡明显增多，而且Caspase-3的变化发生在神经元亡增多之前，提示Caspase-3可能参与了KA致惊厥大鼠海马神经元凋亡的发生。     

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。     

匹罗卡品致痫大鼠海马一氧化氮水平和caspase-3 mRNA表达的动态变化

目的探讨大鼠癫(疒间)持续状态(SE)后海马一氧化氮(NO)与caspase-3 mRNA表达的改变及相互关系.方法采用匹罗卡品腹腔注射建立大鼠SE模型,用比色法和逆转录-聚合酶链反应(RT-PCR)技术在不同时相点检测大鼠海马NO水平与caspase-3 mRNA的表达.结果大鼠海马NO含量在SE后6 h迅速升高,48～72 h虽有所降低,但仍明显高于对照组(均P<0.01);SE后7 d,海马NO含量仍高于正常,但差异无显著性.大鼠海马caspase-3 mRNA表达于SE后6 h开始增多(P<0.05),SE后48 h达到高峰(P<0.01),72 h开始降低,SE后7 d,caspase-3 mRNA表达仍高于对照组,但差异无显著性(P>0.05).结论 caspase-3 mRNA表达升高在NO水平升高之后,并与NO保持相似的变化趋势,提示SE后caspase-3的激活可能与NO神经毒性作用有关.     

致痫大鼠海马神经元氨基酸类物质含量变化的研究

目的 研究癫痫发病中海马神经元氨基酸类物质的合成，分泌情况，探索癫痫发病的可能机制。方法 用马桑内酯致痫培养大鼠海马神经元细胞，用高效液相色谱法测定培养神经元细胞内外谷氨酸（Glu) ,天门冬氨酸（Asp)，γ-氨基丁酸（GABA），甘氨酸（Gly）的含量。结果 致痫海马神经元细胞Glu合成相对增加，分泌显著性增加（P＜0．01）；Asp合成没有明显增加（P＞0．05），或相对养活，分泌显著性增加（P＜0．01）；GABA分泌显著性减少（P＜0．01），合成相对地减少；Gly合成分泌有显著性减少（P＜0．01）。结论 癫痫发病中，痫性神经元细胞合成和／或分泌异常是癫痫发病中氨基酸类神经递质平衡紊乱的基础。     

褪黑素对癫(癎)大鼠海马神经元凋亡及半胱氨酸蛋白酶-3表达的影响

目的观察褪黑素（Mel）对癫癇大鼠海马神经元凋亡及半胱氨酸蛋白酶（caspase）-3表达的影响。方法采用匹罗卡品（Pilo）制作大鼠癫癇持续状态（SE）模型,随机分为Pilo组、Mel组和对照组,用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记法（TUNEL）染色和免疫组化技术检测大鼠海马神经元凋亡数和caspase-3的表达,并与对照组比较。结果SE后6h,Pilo组开始出现少量TUNEL阳性细胞;SE后72h,达到高峰;SE后7d,TUNEL阳性细胞开始减少。SE后6h,Pilo组大鼠海马caspase-3阳性细胞数增多,主要集中于CA1和CA3区;SE后48h,达到高峰;SE后72h,阳性细胞数开始减少;SE后7d,caspase-3表达基本恢复正常。Mel组各时间点大鼠海马TUNEL阳性细胞数和caspase-3表达均明显低于Pilo组大鼠（均P〈0.01）。结论Mel可减少癫癇大鼠海马神经元凋亡,抑制caspase-3的表达,起到神经保护作用。     

Caspase-3在癫痫模型大鼠海马神经细胞凋亡中作用的研究

目的对癫痫模型海马神经细胞凋亡中caspase-3的作用机制进行实验研究。方法以TUNEL法检测KA致痫大鼠海马神经细胞凋亡情况，以Western blot法检测其中eIF2α的表达变化。取模型鼠海马组织构建cDNA文库，构建caspase-3的酵母三杂交诱饵载体，进行筛库实验。结果在癫痫发作后12h TUNEL阳性神经元增加，72h达高峰；发作后24hm现eIF2α被caspase-3酶切的片段，逐渐增加至72h。制作成功cDNA文库，构建了caspase-3的酵母三杂交诱饵载体，筛库获得caspase-3的新底物Mizl。结论在癫痫大鼠海马神经细胞凋亡中eIF2α被caspase-3酶切。酵母三杂交寻找caspase-3下游底物有可行性，从癫痫大鼠海马中获得caspase-3的底物Mizl。     

两种不同用药途径点燃大鼠海马神经元线粒体损伤及caspase-3表达

目的观察两种不同用药途径点燃大鼠海马CA3区神经元线粒体超微结构损伤及caspase-3表达。方法分别采用海人酸腹腔注射（A组）和尾静脉注射（B组）诱发大鼠癫痫持续状态（SE）。于SE终止后不同时间点取海马，电镜观察线粒体的超微结构，半定量RT-PCR和免疫组化方法分别检测caspase-3在mRNA和蛋白水平的表达，并与对照组（正常大鼠）比较。结果A组潜伏期为（97±11）min，神经元呈凋亡特征，线粒体肿胀；B组潜伏期为（48±13）min，神经元呈坏死表现，线粒体肿胀且伴膜的崩解。A组于SE后12h出现caspase-3 mRNA的表达增高（与对照组相比，P〈0．001），24h达高峰，并持续至48h；B组未检测到caspase-3 mRNA的明显增高（与对照组相比，P〉0．05）。两组动物均在SE后6h出现caspase-3蛋白水平的表达增高（P〈0．001），24h达顶峰；A组高表达持续至48h，B组在48h显著降低。结论两种不同的点燃方式导致了大鼠不同程度的线粒体损伤和caspase-3在不同水平的表达，进而决定了神经元死亡的分子机制。     

Activation of caspase-3 in beta-amyloid-induced apoptosis of cultured rat cortical neurons.

Amyloid beta protein (Abeta) has been thought to participate in the neurodegeneration associated with Alzheimer's disease. We here report on caspase-3 activation by Abeta-treatment of cultured neurons. Treatment of rat primary cortical culture with Abeta 25-35, an active fragment of Abeta, induced neuronal death as determined by a decrease in neuron-specific microtubule-associated protein 2 (MAP2)-like immunoreactivity and by the release of cellular lactate dehydrogenase (LDH). Abeta 25-35 also induced elevation of caspase-3-like Ac-DEVD-MCA cleavage activity in advance of neuronal death with similar concentration-dependency for neuronal death. Inhibitor sensitivity of the Abeta-induced proteolytic activity was similar to that of human recombinant caspase-3. Cleavage of pro-caspase-3 and cleavage of its endogenous substrates, poly (ADP-ribose) polymerase (PARP) and alpha-fodrin, were produced by Abeta-treatment. A caspase-3 inhibitor, Ac-DEVD-CHO, prevented Abeta-induced DNA fragmentation and cleavage of alpha-fodrin, but not of PARP. Caspase inhibitor of broad specificity, Z-VAD-CH(2)-DCB, additionally prevented Abeta-induced cleavage of PARP and some early loss of cell membrane integrity measured by LDH release. However, Abeta-induced condensation of nuclear chromatin and most of the late disintegration of cell membranes were not prevented in the presence of these caspase inhibitors. These results suggest that activation of both caspase-3 and caspase(s) other than caspase-3 play distinct roles in Abeta-induced apoptosis of rat cortical neurons. Furthermore, in the presence of caspase inhibitors, Abeta-induced neuronal death still occurred with different morphological features.     

海人酸致(疒间)大鼠海马CA3区神经元线粒体与细胞核损伤及caspase-3表达的研究

目的观察海人酸（KA）诱导的癫痫持续状态（SE）大鼠海马CA,区神经元线粒体与细胞核超微结构的损伤及caspase-3表达的变化。方法用KA诱导大鼠SE2h。分别于SE终止后第3h、12h、24h取海马CA,区制作切片,光镜下观察神经元的变化,电镜下观察线粒体和细胞核的超微结构;免疫组化方法检测相同部位caspase-3的表达变化。结果光镜下SE后24h神经元出现排列散乱、胞体皱缩、胞浆红染以及胞核固缩。电镜下SE后3h,可见线粒体嵴肿胀及膜的崩解;SE后24h细胞核染色质明显边聚。Caspase-3平均阳性细胞数及灰度值于SE后12h较正常对照组显著增加（均P〈0．05）;24h出现极显著增加（均P〈0．01）。结论SE后早期海马神经元线粒体损伤可能是神经元损伤的关键环节。     

海人酸致癎大鼠海马CA_3区神经元线粒体与细胞核损伤及caspase-3表达的研究

目的观察海人酸(KA)诱导的癫疒间持续状态(SE)大鼠海马CA3区神经元线粒体与细胞核超微结构的损伤及caspase-3表达的变化。方法用KA诱导大鼠SE 2 h。分别于SE终止后第3 h、12 h、24 h取海马CA3区制作切片,光镜下观察神经元的变化,电镜下观察线粒体和细胞核的超微结构;免疫组化方法检测相同部位caspase-3的表达变化。结果光镜下SE后24 h神经元出现排列散乱、胞体皱缩、胞浆红染以及胞核固缩。电镜下SE后3 h,可见线粒体嵴肿胀及膜的崩解;SE后24 h细胞核染色质明显边聚。Caspase-3平均阳性细胞数及灰度值于SE后12 h较正常对照组显著增加(均P<0.05);24 h出现极显著增加(均P<0.01)。结论SE后早期海马神经元线粒体损伤可能是神经元损伤的关键环节。     

Activation of caspase-3 in β-amyloid-induced apoptosis of cultured rat cortical neurons

Amyloid β protein (Aβ) has been thought to participate in the neurodegeneration associated with Alzheimer's disease. We here report on caspase-3 activation by Aβ-treatment of cultured neurons. Treatment of rat primary cortical culture with Aβ 25–35, an active fragment of Aβ, induced neuronal death as determined by a decrease in neuron-specific microtubule-associated protein 2 (MAP2)-like immunoreactivity and by the release of cellular lactate dehydrogenase (LDH). Aβ 25–35 also induced elevation of caspase-3-like Ac-DEVD-MCA cleavage activity in advance of neuronal death with similar concentration-dependency for neuronal death. Inhibitor sensitivity of the Aβ-induced proteolytic activity was similar to that of human recombinant caspase-3. Cleavage of pro-caspase-3 and cleavage of its endogenous substrates, poly (ADP-ribose) polymerase (PARP) and α-fodrin, were produced by Aβ-treatment. A caspase-3 inhibitor, Ac-DEVD-CHO, prevented Aβ-induced DNA fragmentation and cleavage of α-fodrin, but not of PARP. Caspase inhibitor of broad specificity, Z-VAD-CH₂-DCB, additionally prevented Aβ-induced cleavage of PARP and some early loss of cell membrane integrity measured by LDH release. However, Aβ-induced condensation of nuclear chromatin and most of the late disintegration of cell membranes were not prevented in the presence of these caspase inhibitors. These results suggest that activation of both caspase-3 and caspase(s) other than caspase-3 play distinct roles in Aβ-induced apoptosis of rat cortical neurons. Furthermore, in the presence of caspase inhibitors, Aβ-induced neuronal death still occurred with different morphological features.     

Suppression by topiramate of epileptiform burst discharges in hippocampal CA3 neurons of spontaneously epileptic rat in vitro

Topiramate, a novel antiepileptic drug, inhibits the seizures of spontaneously epileptic rat (SER), a double mutant (zi/zi, tm/tm) which exhibits both tonic convulsion and absence-like seizures from the age of 8-weeks. Hippocampal CA3 pyramidal neurons in SER show a long-lasting depolarization shift with accompanying repetitive firing when a single electrostimulation is delivered to the mossy fibers in vitro. The effects of topiramate on the excitability of CA3 pyramidal neurons in SER were examined to elucidate the mechanism underlying the antiepileptic action. Intracellular recordings were performed in 23 hippocampal slice preparations of 16 SER aged 8–17 weeks. Topiramate (10–100 μM) dose-dependently inhibited the depolarizing shifts with repetitive firing induced by mossy fiber stimulation without affecting the first spike and resting membrane potentials in hippocampal CA3 neurons of SER. Higher dose of topiramate (100 μM) sometimes inhibited the first spike, and decreased excitatory postsynaptic potentials in the SER CA3 neurons. However, topiramate up to 100 μM did not affect the single action potential elicited by the stimulation in the hippocampal CA3 neurons of age-matched Wistar rat devoid of the seizure. Application of topiramate (100 μM) did not significantly affect the firing induced by depolarizing pulse applied in the CA3 neurons of the SER. In addition, topiramate (100 μM) had no effects on the Ca²⁺ spike induced by intracellularly applied depolarizing pulse in the presence of tetrodotoxin and tetraethylammonium. In contrast, a dose-dependent inhibition of depolarization and repetitive firing induced by bath application of glutamate in CA3 pyramidal neurons was obtained with topiramate (10–100 μM). Furthermore, topiramate (100 μM) decreased the number of miniature postsynaptic potential of CA3 pyramidal neurons of SER. In patch clamp whole cell recording using acutely dissociated hippocampal CA3 neurons from SER aged 8-weeks and age-matched normal Wistar rats, there were no remarkable effects on voltage dependent Ca²⁺ current with topiramate up to 300 μM in either animal; the current was completely blocked by Cd²⁺ at a concentration of 1 mM. These findings suggest that topiramate inhibits release of glutamate from the nerve terminals and/or abnormal firing of the CA3 pyramidal neurons of SER by mainly blocking glutamate receptors in the neurons.