小鼠急性致痫后海马活化素βA基因表达的变化与意义初探

目的 探讨小鼠癫痫持续状态（Status epilepticus，SE）后海马活化素βA基因的表达与意义。方法 采用毛果芸香碱诱导的SE小鼠模型，应用逆转录-聚合酶链反应（RT-PCR）及原位杂交观察SE后海马活化素βA基因表达的动态变化；应用尼氏染色观察海马病理形态结构的变化。结果 SE后3h海马活化素SAmRNA表达即显著增高，6h达高峰，持续至约24h后开始回落，48h恢复近正常水平；活化素pAmR-NA表达最先在海马CA2及DG区上调，高峰时CA3区亦见明显表达，48h后仅CA2区仍可见阳性表达；海马活化素βA mRNA水平与神经元抗损伤力有关。结论 毛果芸香碱诱导的SE能明显上调海马活化素βA mRNA表达，其水平的上调可能有助于增强海马神经元抗兴奋性损伤的能力。     

小鼠急性致癎后海马活化素βA基因表达的变化与意义初探

目的探讨小鼠癫癎持续状态(Status epilepticus,SE)后海马活化素βA基因的表达与意义.方法采用毛果芸香碱诱导的SE小鼠模型,应用逆转录-聚合酶链反应(RT-PCR)及原位杂交观察SE后海马活化素βA基因表达的动态变化;应用尼氏染色观察海马病理形态结构的变化.结果SE后3 h海马活化素βA mRNA表达即显著增高,6 h达高峰,持续至约24 h后开始回落,48 h恢复近正常水平;活化素βA mR-NA表达最先在海马CA2及DG区上调,高峰时CA3区亦见明显表达,48 h后仅CA2区仍可见阳性表达;海马活化素βA mRNA水平与神经元抗损伤力有关.结论毛果芸香碱诱导的SE能明显上调海马活化素βAmRNA表达,其水平的上调可能有助于增强海马神经元抗兴奋性损伤的能力.     

小鼠急性致痫间后海马活化素βA基因表达的变化与意义初探

目的探讨小鼠癫持续状态(Statusepilepticus,SE)后海马活化素βA基因的表达与意义。方法采用毛果芸香碱诱导的SE小鼠模型,应用逆转录聚合酶链反应(RTPCR)及原位杂交观察SE后海马活化素βA基因表达的动态变化;应用尼氏染色观察海马病理形态结构的变化。结果SE后3h海马活化素βAmRNA表达即显著增高,6h达高峰,持续至约24h后开始回落,48h恢复近正常水平;活化素βAmRNA表达最先在海马CA2及DG区上调,高峰时CA3区亦见明显表达,48h后仅CA2区仍可见阳性表达;海马活化素βAmRNA水平与神经元抗损伤力有关。结论毛果芸香碱诱导的SE能明显上调海马活化素βAmRNA表达,其水平的上调可能有助于增强海马神经元抗兴奋性损伤的能力。     

锂-毛果芸香碱致痫大鼠早期大脑NG2和O4表达及意义

目的探讨氯化锂-毛果芸香碱(匹罗卡品)致疒0 间大鼠早期大脑少突胶质前体细胞变化及意义.方法对雄性成年SD大鼠先后腹腔注射氯化锂、毛果芸香碱,制成癫癎持续状态动物模型;用免疫荧光组织化学法检测癎性发作后早期大鼠大脑皮质和海马CA1区NG2和O4阳性细胞数量.结果和对照组相比,除癫癎后1 d组外其余各组大鼠脑皮质内NG2和O4阳性细胞都有明显的增加;癫癎后1 d组海马CA1区的阳性细胞数明显减少;癫癎后7 d组皮质和海马CA1区NG2和O4阳性细胞数最多.结论氯化锂-毛果芸香碱致癎大鼠早期大脑NG2和O4表达增加,少突胶质前体细胞增多,并且和观测时间相关.     

γ-氨基丁酸能中间神经元的数量变化与颞叶癫癎关系的实验研究

目的 探讨含微白蛋白（PV）、钙视网膜蛋白（CR）、钙结合蛋白-D28K（CB）的梁静慧-氨基丁酸（GABA）能中间神经元在颞叶癫痫发生、发展中的作用。方法 采用氯化锂-匹罗卡品颞叶癫痢大鼠模型,应用免疫组化法分别于制模后6h、12h、24h、7d、15d及60d动态观察海马神经元PV、CR、CB的表达。结果 与对照组相比,实验组大鼠海马PV阳性神经元的数量在CA,区无明显变化,在CA,区呈进行性下降（P〈0．05～0．01）,7d时达最低值;在齿状回门区,6h即出现明显的下降（P〈0．05）,15d时达最低值（P〈0．01）,30d后开始上升,到60d时与对照组相比差异无显著性。实验组大鼠海马各区、各时点CR阳性神经元的数量较对照组均明显下降（P〈0．05～0．01）;在CA3区和CA1区24h组及在齿状回门区15d组数量达最低。CB阳性神经元的数量在CA3区与对照组无明显变化（P〉0．05）;在CA1区,6h后开始减少（P〈0．05）,7d后达最低值（P〈0．01）,然后稍有回升,但仍明显低于对照组（P〈0．05）;齿状回CB阳性神经元的数量7d时开始较对照组明显增加（P〈0．05）,并逐渐升高,60d时达高峰（P〈0．01）。结论 氯化锂-匹罗卡品颞叶癫痢模型中,海马GABA能神经元在CA1区和CA3区的变化可能诱发了颞叶癫痫的发作;在齿状回的改变可能在颞叶癫痫自发性复发性发作的发生和发展中起重要作用。     

腺苷A2A受体拮抗剂对大鼠氯化锂-毛果芸香碱所致癫痫模型的影响

目的研究腺苷A2A受体阻断剂对大鼠氯化锂-毛果芸香碱癫痫持续状态(SE)模型的影响。方法选取50只WD大鼠随机分为对照组、模型组及A2A受体阻断剂组。模型组采用氯化锂-毛果芸香碱腹腔注射复制癫痫模型,A2 A受体阻断剂组在氯化锂-毛果芸香碱注射前15 min予腹腔给药(SCH58261 0.05 mg/kg),对照组给予同等剂量生理盐水。在成功诱导癫痫发作40 min后予地西泮及水合氯醛终止发作,并于发作终止后24 h留取标本。尼氏染色法检测三组中海马神经元损伤情况,Westernblot法检测MAPKs(JNK/p-JNK、P38/p-P38和ERK/p-ERK)表达变化。结果对照组、模型组及A2A受体阻断剂组双侧海马CA3区正常形态神经元计数分别为158.6±8.4、59.8±7.4和123.4±5.0,模型组神经元计数显著低于对照组,差异具有统计学意义(P0.05),A2A受体阻断剂组神经元计数显著高于模型组,差异具有统计学意义(P0.05)。Westernblot法检测显示p-JNK、p-P38和p-ERK在模型组中表达明显增多,在A2A受体阻断剂组中p-JNK和p-P38表达减少。结论氯化锂-毛果芸香碱模型中,腺苷A2A受体阻断剂可能通过抑制p-JNK他p-P38的表达对神经元损伤起到保护作用。     

海人酸致痫大鼠海马结构GABAB受体亚单位表达的研究

目的：探讨海人酸诱导大鼠颞叶癫痫（EP）发作后2种γ-氨基丁酸（GABA）受体亚单位GABABR亚单位1a（GBR1a）和GABABR亚单位2（GBR2）在EP发生、发展中的作用。方法：运用原位杂交及免疫组化法，检测EP发作后GABABR亚单位mRNA及蛋白在海马的表达。结果：致痫早期CA1和CA3区2种亚单位mRNA表达持续低下后逐渐增加，DG区则暂时性下降后很快回升；而免疫反应早期却未见明显改变，随后CA1和CA3区表达处于低水平，DG区和颞叶皮质表达下降后很快恢复。结论：致痫后2种GABAB受体亚单位基因和蛋白表达上调为颞叶EP的内源性自我保护机制。     

Semaphorin-3A与苔藓纤维出芽在毛果芸香碱致痫大鼠中的改变及意义

目的探讨海马Semaphorin-3A(Sema3A)与苔藓纤维出芽(MFS)在癫痫发病机制中的作用。方法通过小剂量多次腹腔注射氯化锂-毛果芸香碱建立癫痫大鼠模型,随机将大鼠分为生理盐水对照组和痫性发作组。痫性发作组分别于药物注射后1、5、7d及3、4周时间点,应用Western blotting法检测大鼠海马Sema3A的表达,同时采用neo-Timm银染观察海马MFS情况。结果生理盐水对照组Sema3A仅有少量表达,痫性发作组1、5d无表达,7d表达明显,3周后亦无表达;痫性发作组1、5d未见MFS,7d可见MFS至齿状回内分子层,3周后明显可见MFS至齿状回分子层。痫性发作组Timm评分与生理盐水对照组比较差异有统计学意义(P<0.05)。结论海马区Sema3A表达变化伴有MFS可能是癫痫发病机制的重要因素之一。     

癫痫持续发作时间与大鼠海马苔藓纤维发芽程度及自发性痫性发作的关系

目的探讨癫痫持续状态(SE)发作时间与致痫大鼠海马苔藓纤维发芽(MFS)程度及自发性痫性发作的关系。方法 104只雄性成年SD大鼠,随机分为对照组和3个SE实验组,建立氯化锂-重复低剂量匹罗卡品致痫大鼠模型;诱发SE30min(A组)、60min(B组)、90min(C组)后注射水合氯醛终止发作。各组大鼠自SE终止发作后于相同实验条件下普通饲养45d,观察大鼠行为及脑电图(EEG)的变化,记录自发性痫性发作的发生率。通过苏木精-伊红染色、Nissl染色和Timm硫化银组织化学染色方法观察各实验组海马MFS情况。结果氯化锂-重复低剂量匹罗卡品成功诱导大鼠SE的发生,发作程度均达Ⅳ级以上,EEG类似人类颞叶癫痫。80%的大鼠癫痫持续状态均发展为自发痫性发作,与SE时间无关。与对照组相比,实验A、B、C三组双侧海马CA3区均表现MFS(P0.05)。实验B组与A、C组相比,CA3区MFS明显增加(P0.05)。结论氯化锂-重复低剂量匹罗卡品可诱导SE,癫痫持续发作60min后终止的大鼠海马CA3区MFS明显增加,SE发作时间与海马MFS程度并不一定呈正相关。     

氯化锂-匹罗卡品致痫大鼠海马EphA5及ephrinA3的表达及意义

目的探讨颞叶癫痫发作后海马EphA5及ephrinA3基因的表达变化和轴突出芽的关系。方法建立氯化锂-匹罗卡品颞叶癫痫大鼠模型,利用原位杂交方法检测致痫后12h、24h、7d、15d、30d、60d海马CA3区、CA1区EphA5及ephrinA3 mRNA的表达,快速Golgi染色观察CA1区的轴突出芽。结果致痫后,EphA5 mRNA在CA3区表达下调,ephrinA3 mRNA在CA1区表达下调,均在7d降至最低点,与对照组相比差异有显著意义(P<0.01),此后逐渐回升,但15d时仍低于对照组(P<0.05),在30d和60d与对照组相比差异无统计学意义(P>0.05)。快速Golgi染色显示,对照组大鼠CA1区轴突走行正常,匹罗卡品致大鼠SE后7dCA1区锥体细胞层出现显著增多的轴突染色。结论CA3区的EphA5和CA1区的ephrinA3的表达下调可能与CA1区的轴突出芽、突触重建有关。     

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.     

Prolonged infusion of inhibitors of calcineurin or L-type calcium channels does not block mossy fiber sprouting in a model of temporal lobe epilepsy

Purpose:   It would be useful to selectively block granule cell axon (mossy fiber) sprouting to test its functional role in temporal lobe epileptogenesis. Targeting axonal growth cones may be an effective strategy to block mossy fiber sprouting. L-type calcium channels and calcineurin, a calcium-activated phosphatase, are critical for normal growth cone function. Previous studies have provided encouraging evidence that blocking L-type calcium channels or inhibiting calcineurin during epileptogenic treatments suppresses mossy fiber sprouting.
Methods:   Rats were treated systemically with pilocarpine to induce status epilepticus, which lasted at least 2 h. Then, osmotic pumps and cannulae were implanted to infuse calcineurin inhibitors (FK506 or cyclosporin A) or an L-type calcium channel blocker (nicardipine) into the dorsal dentate gyrus. After 28 days of continuous infusion, extent of mossy fiber sprouting was evaluated with Timm staining and stereological methods.
Results:   Percentages of volumes of the granule cell layer plus molecular layer that were Timm-positive were similar in infused and noninfused hippocampi.
Conclusions:   These findings suggest inhibiting calcineurin or L-type calcium channels does not block mossy fiber sprouting in the pilocarpine-treated rat model of temporal lobe epilepsy.     

The Role of Mossy Cell Death and Activation of Protein Synthesis in the Sprouting of Dentate Mossy Fibers: Evidence from Calretinin and Neo-Timm Staining in Pilocarpine-Epileptic Mice

Summary: Mossy fiber sprouting is a major anatomical reorganization seen in patients with temporal lobe epilepsy and animal models of epilepsy. The final outcome of this reorganization is viewed by many as epileptogenic. Yet, important and relevant data from both human and animal models of epilepsy challenge this prevailing view. Regardless of the outcome of this debate, understanding of the mechanisms that underlie mossy fiber sprouting (MFS) might contribute to our understanding of both the adaptive and maladaptive changes that take place in the nervous system after injury. Available evidence suggests that two events might be crucial for mossy fibers to sprout in epilepsy: the death of mossy cells and the synthesis of trophic factors. The availability of means that prevent MFS, which is normally triggered after induction of status epilepticus, allow for the testing of hypotheses regarding the need for and the sufficiency of specific events for mossy fibers to sprout. We present data on a specific marker for mossy cells, calretinin, in the pilocarpine model of epilepsy in mice. Our data suggest that in the presence of a protein synthesis inhibitor status epilepticus—induced death of mossy cells is not sufficient to trigger mossy fiber sprouting. We suggest that both events, mossy cell death and synthesis of trophic factors, might be necessary for robust MFS to ensue.     

Sprouting of mossy fibers and the vacating of postsynaptic targets in the inner molecular layer of the dentate gyrus

Aberrant mossy fiber sprouting, which presumably results from hilar mossy cell death after status epilepticus (SE), is a frequently studied feature of temporal lobe epilepsy. Although mossy fiber sprouting can be suppressed by the protein synthesis inhibitor cycloheximide, spontaneous seizures remain unaltered. We have investigated the mechanisms underlying the ability of cycloheximide to block SE-induced mossy fiber sprouting in the inner molecular layer of dentate gyrus (IML). Pilocarpine-induced SE in the presence of cycloheximide resulted in a reduced number of injured hilar cells compared to rats not pretreated with cycloheximide. Presumed mossy cells, identified by calcitonin gene related peptide (CGRP) immunohistochemistry, were not significantly reduced in either group 60 days after SE. Whereas controls had a strong band of CGRP-positive fibers (putative mossy cell axons) and no neo-Timm stained fibers in the IML, pilocarpine-treated rats had no CGRP fibers and strong neo-Timm staining. Cycloheximide-pilocarpine-treated animals, in contrast, had CGRP and neo-Timm staining similar to controls. Cycloheximide might protect hilar CGRP-positive cells during SE and, by allowing those cells to retain their normal axonal projection, prevent mossy fiber sprouting. The recently suggested "irritable" mossy cell hypothesis relies on the survival of mossy cells for network hyperexcitability. We hypothesized that CGRP may be a marker for a subpopulation of relatively resistant mossy cells in rats, which, if they survive injury, may become irritable and contribute to hyperexcitability. We suggest that cycloheximide prevents SE-induced mossy fiber sprouting by preventing the loss of hilar CGRP-positive cells (putative mossy cells).     

N-cadherin在颞叶癫痫海马苔藓纤维出芽和突触重组中的作用

目的 探讨神经性钙粘附分子(N-cadherin)在癫痫状态后海马苔藓纤维出芽和突触重组中的作用。方法取锂一匹罗卡品诱导大鼠癫痫持续状态及慢性自发性颞叶癫痫发作期的大鼠脑片，用Timm染色和免疫组化的方法分别检测苔藓纤维出芽和N-cadherin在大鼠海马组织中的表达。结果癫痫状态后第2周和第4周的实验组大鼠可见到苔藓纤维出芽，穿越齿状回颗粒细胞层到达内分子层，并在此形成一条致密的层状带(Timm染色)。免疫组化染色发现实验组大鼠在第2周和第4周，海马齿状回内分子层可以看到强染色，并形成一条致密带，与Timm染色时观察到的条带一致。结论癫痫状态后在海马齿状回内分子层N-cadherin的表达上调．N-cadherin可能参与了癫痫后苔藓纤维出芽和突触重组过程。     

8-hydroxy-dipropylaminotetralin promotes neural plasticity in epileptic rats with depression

Rats with chronic pilocarpine-induced temporal lobe epilepsy complicated with depression were studied. Anti-5-bromodeoxyuridine immunofluorescence staining and Timms staining showed that neurogenesis within the hippocampal dentate gyrus and mossy fiber sprouting were increased in model rats. Neurogenesis within the hippocampal dentate gyrus was further enhanced, while mossy fiber sprouting was decreased in model rats administered carbamazepine alone or in combination with the 5-hydroxytryptamine 1A receptor agonist, 8-hydroxy-dipropylaminotetralin (0.1 and 1 mg/kg). Among the groups, the effect was the most significant in rats receiving carbamazepine in conjunction with 1 mg/kg 8-hydroxy-dipropylaminotetralin. Thus, high dose 8-hydroxy-dipropylaminotetralin can improve neural plasticity in epileptic rats with depression.     

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。     

Status epilepticus-induced hilar basal dendrites on rodent granule cells contribute to recurrent excitatory circuitry

Mossy fiber sprouting into the inner molecular layer of the dentate gyrus is an important neuroplastic change found in animal models of temporal lobe epilepsy and in humans with this type of epilepsy. Recently, we reported in the perforant path stimulation model another neuroplastic change for dentate granule cells following seizures: hilar basal dendrites (HBDs). The present study determined whether status epilepticus-induced HBDs on dentate granule cells occur in the pilocarpine model of temporal lobe epilepsy and whether these dendrites are targeted by mossy fibers. Retrograde transport of biocytin following its ejection into stratum lucidum of CA3 was used to label granule cells for both light and electron microscopy. Granule cells with a heterogeneous morphology, including recurrent basal dendrites, and locations outside the granule cell layer were observed in control preparations. Preparations from both pilocarpine and kainate models of temporal lobe epilepsy also showed granule cells with HBDs. These dendrites branched and extended into the hilus of the dentate gyrus and were shown to be present on 5% of the granule cells in pilocarpine-treated rats with status epilepticus, whereas control rats had virtually none. Electron microscopy was used to determine whether HBDs were postsynaptic to axon terminals in the hilus, a site where mossy fiber collaterals are prevalent. Labeled granule cell axon terminals were found to form asymmetric synapses with labeled HBDs. Also, unlabeled, large mossy fiber boutons were presynaptic to HBDs of granule cells. These results indicate that HBDs are present in the pilocarpine model of temporal lobe epilepsy, confirm the presence of HBDs in the kainate model, and show that HBDs are postsynaptic to mossy fibers. These new mossy fiber synapses with HBDs may contribute to additional recurrent excitatory circuitry for granule cells.     

Epilepsy after early-life seizures can be independent of hippocampal injury

Prolonged early-life seizures are considered potential risk factors for later epilepsy development, but mediators of this process remain largely unknown. Seizure-induced structural damage in hippocampus, including cell loss and mossy fiber sprouting, is thought to contribute to the hyperexcitability characterizing epilepsy, but a causative role has not been established. To determine whether early-life insults that lead to epilepsy result in similar structural changes, we subjected rat pups to lithium-pilocarpine-induced status epilepticus during postnatal development (day 20) and examined them as adults for the occurrence of spontaneous seizures and alterations in hippocampal morphology. Sixty-seven percent of rats developed spontaneous seizures after status epilepticus, yet only one third of these epileptic animals exhibited visible hippocampal cell loss or mossy fiber sprouting in dentate gyrus. Most epileptic rats had no apparent structural alterations in the hippocampus detectable using standard light microscopy methods (profile counts and Timm's staining). These results suggest that hippocampal cell loss and mossy fiber sprouting can occur after early-life status epilepticus but may not be necessary prerequisites for epileptogenesis in the developing brain.     

Association Between the Density of Mossy Fiber Sprouting and Seizure Frequency in Experimental and Human Temporal Lobe Epilepsy

Summary: Purpose : If the sprouting of granule cell axons or mossy fibers in the dentate gyrus is critical for the generation of spontaneous seizures in temporal lobe epilepsy (TLE), one could hypothesize that epileptic animals or humans with increased sprouting would have more frequent seizures. This hypothesis was tested by analyzing the data gathered from experimental and human epilepsy.
Methods : In experiment I (rats with "newly diagnosed" TLE), self-sustained status epilepticus was induced in rats by electrically stimulating the amygdala. Thereafter, the appearance of spontaneous seizures was monitored by continuous video-electroencephalography (EEG) until the animal developed two spontaneous seizures and for 11 d thereafter. Rats were perfused for histology, and mossy fibers were stained using the Timm method. In experiment II (rats with "recently diagnosed" TLE), status epilepticus was induced in rats and the development of seizures was monitored by video-EEG for 24 h/d every other day for 60 days. All animals were then perfused for histology. In experiment III (rats with "chronic" TLE), animals were monitored by video-EEG for 24 h/d every other day for 6 months before histologic analysis. To assess mossy fiber sprouting in human TLE, hippocampal sections from 31 patients who had undergone surgery for drug-refractory TLE were stained with an antibody raised against dynorphin.
Results and Conclusions : Our data indicate that the density of mossy fiber sprouting is not associated with the total number of lifetime seizures or the seizure frequency in experimental or human TLE.