戊四氮点燃模型大鼠GSK-3β活性的动态变化及其与苔藓纤维出芽的关系

目的 探讨戊四氮点燃模型大鼠GSK-3β活性变化与苔藓纤维出芽的关系.方法 取戊四氮点燃模型大鼠给药后3 d、1、2、4和6周的脑片,通过Timm染色观察苔藓纤维出芽的动态变化;取各时间点的大鼠海马组织,通过酶活性测定方法 检测GSK-3β活性变化.结果 戊四氮组各时间点GA3区苔藓纤维出芽评分均有显著性差异(P＜0.05);从3 d起评分逐渐增加,2周时达高峰并维持至6周.在点燃过程中海马GSK-3β蛋白活性逐渐增高,2周达高峰,4、6周表达逐渐下调到生理盐水对照组水平,除6周组外各时间点与相应时间点生理盐水对照组比较差异均有统计学意义.结论 GSK-3β通过活性上调参与了苔藓纤维出芽过程,促进了癫(癎)的发生.     

Tau蛋白在点燃大鼠海马苔藓纤维出芽中的作用探讨

目的观察总tau蛋白及其p-ptauser202在戊四氮点燃癫模型海马中的表达变化,探讨其在苔藓纤维出芽中的作用。方法 180只雄性SD大鼠随机分为对照组(腹腔注射生理盐水)和模型组(腹腔注射戊四氮),均n=90。于不同的时间点应用Timm染色观察苔藓纤维出芽,免疫组化和Western blot检测各时间点海马总tau蛋白及p-ptauser202蛋白表达情况。结果模型组各时间点CA1、CA3、DG区苔藓纤维出芽较对照组明显增多,差异有统计学意义(P<0.05);模型组第1周CA1区、CA3区,第2周DG区的p-ptauser202蛋白表达与对照组比较明显增多,差异均有统计学意义(分别为CA1区P<0.05,CA3区P<0.01,DG区P<0.01);门区(H区)tau蛋白及p-ptauser202蛋白在各时间点的表达明显增多,差异有显著统计学意义(P<0.01);对照组无动态变化。结论 tau蛋白可能通过其磷酸化水平的增高参与癫点燃大鼠的苔藓纤维出芽,在癫的发生和发展中起重要作用。     

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。     

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。     

耐药性癫癎患者术后脑组织中Tau蛋白的表达

目的研究Tau蛋白在耐药性癫癎患者脑组织中的表达,探讨其在耐药性癫癎发病机制中的作用。方法采用免疫组化法检测48例耐药性癫癎患者海马及颞叶皮层中Tau蛋白的表达,同步观察海马苔藓纤维芽生,并与对照组进行比较。结果耐药性癫癎组和对照组脑组织中总Tau蛋白表达无明显差异,而磷酸化Tau蛋白在耐药性癫癎患者海马CA3区(0·0450±0·0115)及齿状回内分子层(0·0463±0·0120)表达增多,同步伴有海马苔藓纤维芽生(耐药性癫癎组:3·18±0·35,对照组:0·61±0·19)。结论磷酸化Tau蛋白表达增强可能是耐药性癫癎患者海马突触重建的重要机制,改变磷酸化Tau蛋白的表达有可能改善耐药性癫癎患者的预后。     

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。     

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.     

癫(癎)幼鼠海马和颞叶皮质区缝隙连接蛋白43和突触体素表达的变化

目的观察神经元缝隙连接蛋白43(Cx43)和突触体素(synaptophysin P38)在戊四氮(PTZ)点燃癫癎幼鼠海马及颞叶皮质区中的表达,探讨两者与癫癎的关系及其在癫形成中的作用。方法将50只21日龄Wistar大鼠分为对照组和实验组。实验组采用PTZ点燃癫癎幼鼠,按点燃进程分为Ⅰ级、Ⅱ级、Ⅲ级、Ⅳ级及Ⅴ级发作组。采用免疫组化和图像分析技术,观察海马及颞叶皮质区Cx43和P38表达的变化。结果应用PTZ点燃后,实验各组幼鼠海马及颞叶皮质区Cx43和P38的表达明显高于对照组(P<0.01),且随发作级别的增高,幼鼠海马及颞叶皮质各区Cx43和P38的表达均增加。但各组间海马区和颞叶皮质区Cx43和P38的表达情况的比较差异无统计学意义(P>0.05)。结论Cx43和P38的表达水平与癫癎的发生发展有密切关系,为研究小儿癫癎的病因及发病机制提供依据。     

托吡酯对戊四氮致癫癎大鼠海马AQP4表达水平的影响

目的探讨托吡酯对戊四氮致癫癎大鼠海马AQP4表达水平的影响。方法将30只Wistar大鼠随机分为戊四氮致癫癎组、托吡酯干预组和正常对照组，每组各10只；癫癎模型点燃后在不同时相点灌注取材，通过HE染色观察大鼠海马神经元的变化，并应用免疫组化法检测大鼠海马AQP4表达水平。结果HE染色显示托吡酯干预组神经元变性和坏死较戊四氮致癫癎组明显减轻；免疫组化显示戊四氮致癫癎组在致癫癎后12hAQP4的表达显著增强，致癫癎后24h达高峰，托吡酯干预组在致癫癎后12h～36h各时相点AQP4表达水平均分别低于戊四氮致癫癎组相应时间点（P〈0．05）。结论托吡酯通过下调大鼠海马AQP4的表达可能参与了对大鼠海马神经元的保护过程。     

抗癫癎药物与大鼠海马CA1区胶质细胞TUNEL阳性表达关系的研究

目的:探讨抗癫癎药物对大鼠海马胶质细胞凋亡的影响。方法:35只60天龄SD大鼠随机分为生理盐水组(NS)、戊四氮(PTZ)组、卡马西平组(CBZ)、丙戊酸钠组(VPA)、苯妥英钠组(PHT)、托吡酯组(TPM)、拉莫三嗪组(LTG)7组,起始体重(200±20)g,戊四氮点燃其中6组制作癫癎模型,再给与抗癫癎药物治疗3周,应用TUNEL法观察大鼠海马胶质细胞的阳性表达率。结果:CA1区胶质细胞TUNEL阳性表达:NS组阳性率4.195%,PTZ组阳性率6.536%,CBZ组阳性率4.321%,VPA组阳性率5.587%,4组之间TUNEL阳性表达率差异无显著性(χ2=1.158,P>0.05);PHT组阳性率24.460%,TPM组阳性率21.605%,LTG组阳性率18.902%,三组之间TUNEL阳性表达率差异无显著性(χ2=1.378,P>0.05)。NS组、PTZ组、CBZ组、VPA组与PHT组、TPM组、LTG组之间TUNEL阳性表达率差异有显著性(χ2=70.227,P<0.005)。结论:大鼠癫癎模型经PTH、TPM、LTG治疗后,海马CA1区存在TUNEL阳性胶质细胞。     

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.     

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。     

Association between mossy fiber sprouting and expression of semaphorin-3f protein in dentate gyrus of hippocampus in lithium-pilocarpine-induced status epilepticus mouse model

Objectives: Mossy fiber sprouting is involved in the pathogenesis of mesial temporal lobe epilepsy. But the exact mechanism of formation of mossy fiber sprouting is still unclear. Semaphorin-3f protein could inhibit the growth of neuron axons. The aim of this research is to evaluate the association between semaphorin-3f expression and mossy fiber sprouting.

Methods: We established pilocarpine-induced status epilepticus (PISE) models firstly. Then, mossy fiber sprouting in the hippocampus of PISE models was examined by Timm staining. Expression of semaphorin-3f was evaluated by western blot analysis and immunohistochemical examination. Expression of semaphorin-3f protein in different subregions of hippocampus and its relationship with mossy fiber sprouting were studied.

Results: We found that in PISE group, mossy fiber sprouting appeared in dentate gyrus (DG) region. It started to develop in the latent phase of PISE group and increased significantly in the chronic phase. Expression of semaphorin-3f protein in DG region started to decrease in the latent phase, and stayed at low level in the chronic phase. No such change was found in the other groups.

Conclusions: These results indicate that the decrease in semaphorin-3f expression in DG region was in parallel to the change of mossy fiber sprouting in PISE models, suggesting that mossy fiber sprouting is closely associated with reduced expression of semaphorin-3f in this model.     

Mossy fiber synaptic reorganization induced by kindling: time course of development, progression, and permanence

Recent studies have revealed that mossy fiber axons of granule cells in the dentate gyrus undergo reorganization of their terminal projections in both animal models of epilepsy and human epilepsy. This synaptic reorganization has been demonstrated by the Timm method, a histochemical technique that selectively labels synaptic terminals of mossy fibers because of their high zinc content. It has been generally presumed that the reorganization of the terminal projections of the mossy fiber pathway is a consequence of axonal sprouting and synaptogenesis by mossy fibers. To evaluate this possibility further, the time course for development of Timm granules, which correspond ultrastructurally to mossy fiber synaptic terminals, was examined in the supragranular layer of the dentate gyrus at the initiation of kindling stimulation with an improved scoring method for assessment of alterations in Timm histochemistry. The progression and permanence of this histological alteration were similarly evaluated during the behavioral and electrographic evolution of kindling evoked by perforant path, amygdala, or olfactory bulb stimulation. Mossy fiber synaptic terminals developed in the supragranular region of the dentate gyrus by 4 d after initiation of kindling stimulation in a time course compatible with axon sprouting. The induced alterations in the terminal projections of the mossy fiber pathway progressed with the evolution of behavioral kindled seizures, became permanent in parallel with the development of longlasting susceptibility to evoked seizures, and were observed as long as 8 months after the last evoked kindled seizure. The results demonstrated a strong correlation between mossy fiber synaptic reorganization and the development, progression, and permanence of the kindling phenomenon.     

TRPC6在匹罗卡品致痫大鼠海马苔藓纤维出芽中的作用

目的 观察传统型瞬时受体电位通道6(TRPC6)蛋白在匹罗卡品致痫大鼠海马中的表达变化,探讨其在海马苔藓纤维出芽中的作用.方法 72只SD大鼠随机分为实验组(n=60)和对照组(n=12).实验组采用氯化锂-匹罗卡品腹腔注射法建立颞叶癫痫模型;对照组腹腔注射等量无菌生理盐水.实验组按癫痫持续状态(SE)后1d、7d、15d、30 d和60 d分为5个亚组,每亚组12只大鼠.以上各亚组及对照组再分为2个小组,分别进行Western blot检测TRPC6及突触重建标志蛋白Synaptophysin在海马中的表达和Timm染色观察海马苔藓纤维出芽并评分.结果 实验组TRPC6蛋白表达量在SE后1d达高峰(P＜0.01),其他时间点均显著高于对照组(P＜0.01).Synaptophysin蛋白表达量在SE后7d、15d、30 d和60 d显著增加(7 d:P＜0.05;15 d、30 d、60 d:P＜0.01),30 d达峰值(P＜0.01).实验组大鼠齿状回内分子层在SE后7d出现Timm颗粒,并呈进行性增加.结论 TRPC6可能参与了苔藓纤维出芽这一过程.     

The cholinergic system modulates kindling and kindling-induced mossy fiber sprouting

In a previous study, our laboratory demonstrated that the intraventricular infusion of nerve growth factor (NGF) accelerated kindling rates and enhanced mossy fiber sprouting in the absence of noticeable kindling-associated neuronal loss. The purpose of the present study was to investigate whether these NGF effects were mediated via the cholinergic system. This study evaluated the effects of the cholinergic agonist pilocarpine and the cholinergic antagonist scopolamine on kindling rates and kindling-induced mossy fiber sprouting in adult rats. The results showed that pilocarpine accelerated kindling rates and enhanced kindling-induced mossy fiber sprouting in the CA3 region of the hippocampus, whereas scopolamine retarded kindling rates and blocked kindling-induced mossy fiber sprouting in the CA3 and IML regions. These findings suggest that the cholinergic system may contribute to the long-term structural and functional alterations that are characteristic of the kindled state. Moreover, these data provide support for the hypothesis that NGF infusions may mediate kindling and kindling-induced mossy fiber sprouting via regulation of the cholinergic system.     

Mossy fiber synaptic reorganization in the epileptic human temporal lobe

The distribution of the mossy fiber synaptic terminals was examined using the Timm histochemical method in surgically excised hippocampus and dentate gyrus from patients who underwent lobectomy of the anterior part of the temporal lobe for refractory partial complex epilepsy. The dentate gyrus of epileptic patients demonstrated intense Timm granules and abundant mossy fiber synaptic terminals in the supragranular region and the inner molecular layer. In contrast, the dentate gyrus of presenescent nonepileptic primates demonstrated no Timm granules in the supragranular region. In nonepileptic senescent primates, occasional very sparse supragranular Timm granules were results are morphological evidence of mossy fiber synaptic reorganization in the temporal lobe of epileptic humans, and suggest the intriguing possibility that mossy fiber sprouting and synaptic reorganization induced by repeated partial complex seizures may play a role in human epilepsy.     

Activation of the dentate gyrus by pentylenetetrazol evoked seizures induces mossy fiber synaptic reorganization

Kindled seizures evoked by electrical stimulation of limbic pathways in the rat induce sprouting and synaptic reorganization of the mossy fiber pathway in the dentate gyrus (DG). To investigate whether seizures evoked by different methods also induce reorganization of this pathway, the distribution of mossy fiber terminals in the DG was examined with Timm histochemistry after systemic administration of pentylenetetrazol, a chemoconvulsant that reduces Cl- mediated GABAergic inhibition. Myoclonic seizures evoked by subconvulsant doses of pentylenetetrazol (24 mg/kg i.p.) were not accompanied by electrographic seizures in the DG, and did not induce mossy fiber sprouting. Generalized tonic-clonic seizures evoked by repeated administration of PTZ (24 mg/kg i.p.) were consistently accompanied by electrographic seizure activity in the DG, and induced sprouting and synaptic reorganization of the mossy fiber pathway. The results demonstrated that repeated generalized tonic-clonic seizures evoked by pentylenetetrazol induced mossy fiber synaptic reorganization when ictal electrographic discharges activated the circuitry of the DG.     

Mossy fiber sprouting in the dentate gyrus in a newly developed epileptic mutant, Ihara epileptic rat

We examined the correlation between seizure activity and development of mossy fiber sprouting in the hippocampal formation using Timm staining in a newly developed Ihara epileptic rat (IER). The sprouting of mossy fibers were clearly shown in the inner molecular portion of the dentate gyrus and in the stratum oriens of CA3 pyramidal cell layer with repeated seizures. A positive correlation between the frequency of generalized tonic and clonic convulsions and the Timm staining score in molecular layer of dentate gyrus was revealed. Sprouting of mossy fiber in IER seems to be linked with seizure activities resulting from epileptic bursts, not to the genetic mutation.