2004/大鼠杏仁核点燃癫痫不同脑区BDNF及其受体TrkB的变化

目的 检测大鼠杏仁核点燃癫痫后不同脑区脑源性神经营养因子（BDNF）及其受体TrkB的表达与定位。方法 建立大鼠杏仁核点燃癫痫模型，应用免疫组化方法观察点燃鼠不同脑区不同点燃时程BDNF及TrkB的表达及含量。结果 点燃后大鼠颞叶及海马BDNF随着点燃次数的增加而升高，并持续至点燃后 49d；TrkB的表达也是随着点燃次数的增加而升高，并持续至点燃后7d（改变同BDNF），点燃1周后表达逐渐减少，至点燃后7周时基本恢复正常。结论 BDNF及TrkB直接参与癫痫的发生与发展。早期具有保护作用，但随着表达的进一步增加，又促进癫痫的发生发展，并一定程度上促进了癫痫发作后的神经细胞凋亡及脑损伤过程。     

慢性癫痫大鼠脑组织中脑源性神经生长因子及其受体的研究

应用免疫组织化学的方法观察了戊四氮诱导的慢性癫痫大鼠脑组织中脑源性神经生长因子（BDNF）及其受体TrkB免疫反映阳性神经元的变化。结果发现慢性癫痫大鼠海马回、齿状回BDNF及TrkB免疫反应阳性神经元数目明显增多。在本次抽搐后3h、72h、7d、10dBDNF阳性神经元均增高,而TrkB阳性神经元仅在末次抽搐后3h升高。24h后恢复到正常水平,结果表明,BDNF及TrkB与癫痫发病有关。     

脊髓慢性压迫性损伤后细胞凋亡和BDNF表达的观察

目的 探讨大鼠脊髓在遭受到持续进行性压迫损伤后神经细胞凋亡以及脑源性神经营养因子（BDNF）及其TrkB受体的变化。方法 将75只SD大鼠分为模型组、对照组和正常组,各25只;根据造模后取材时间,各组再分为1、7、14、21、28 d 5亚组,每亚组5只。胸11~12椎板和硬脊膜之间置入缓膨材料（3 mm×5 mm,厚0.8 mm）制作大鼠慢性压迫性脊髓损伤模型,BBB评分评估行为学变化,TUNEL染色检测细胞凋亡,免疫组化染色检测BDNF及其TrkB受体表达变化。结果 造模后7、14、21、28 d,模型组大鼠BBB评分均明显低于对照组和正常组（P<0.05）,而对照组和正常组均无统计学差异（P>0.05）。模型组大鼠可观察到从脊髓受压开始,神经细胞开始出现凋亡,中央管及前角区域的神经细胞凋亡明显,邻近灰质的白质部分神经胶质细胞凋亡明显;而对照组和正常大鼠未见明显凋亡细胞。模型组大鼠脊髓内BDNF及其TrkB受体呈强阳性,尤其是神经元部位,BDNF及其受体TrkB表达明显,且主要表达在运动类神经元中,随压迫进行,表达逐渐增强,至相对稳定;对照组和正常组大鼠脊髓内BDNF及其TrkB受体表达较少。结论 大鼠脊髓在受到慢性压迫性损伤时,神经细胞凋亡明显,BDNF、TrkB受体表达明显增强。     

BDNF及其受体TrkB mRNA在脑缺血后适应大鼠模型中的表达变化

目的检测脑源性性神经营养因子(BDNF)及其受体酪氨酸激酶B(TrkB)在脑缺血后适应大鼠模型再灌注不同时间窗的表达,探讨BDNF/TrkB在脑缺血后适应中的作用。方法 Wistar大鼠随机分成对照组、缺血-再灌注组(IR)和缺血后适应组(IP),后两组根据再灌注时间的不同各分为6h、12h、24h、48h、72h 5个亚组。线栓法建立局灶性脑缺血-再灌注模型。TTC染色测定脑梗死体积,原位杂交法检测BDNF/TrkB mRNA的表达。结果 IP组大鼠梗死体积较IR组明显减小(P0.05)。IP组各时间点BDNF mRNA及TrkB mRNA表达较IR组均明显升高(P0.05)。结论脑缺血后适应能增加脑缺血-再灌注后BDNF及TrkB的表达,减轻脑梗死体积,BDNF/TrkB在脑缺血后适应后脑缺血-再灌注损伤中发挥了重要保护作用。     

经颅磁刺激对脑梗死大鼠神经功能恢复与皮层BDNF表达的影响

目的研究经颅磁刺激（transcranial magnetic stimulation，TMS）对脑梗死大鼠神经功能恢复和皮层脑源性神经营养因子（Brain derived neurotrophic factor，BDNF）表达的影响。方法成年健康雄性SD大鼠80只，随机分为脑梗死1、7、14、21、28d组及TMS1、7、14、21、28d组，每组各8只；采用线栓法制作左侧大脑中动脉闭塞的脑梗死模型；在规定的时间点行神经功能评定，应用免疫组化的方法检测梗死侧皮层BDNF的表达。结果（1）和脑梗死28d组相比，TMS28 d组大鼠Bederson神经功能评分、平衡木实验、网屏实验评分均较低，两者相比具有显著性差异（P〈0．01）；转棒实验虽评分较低，但2组无显著性差异（P〉0．05）；（2）大鼠脑梗死1d后梗死侧皮层可见较多BDNF阳性表达神经细胞，主要位于梗死灶周围，至第7d表达达高峰，然后开始下降；TMS7、14、21d组梗死侧皮层BDNF表达增加。结论TMS能促进脑梗死大鼠神经功能恢复，机理可能与TMS能增加脑梗死侧皮层BDNF表达有关。     

匹罗卡品致疒间大鼠海马GAP-43与TrkB基因表达及其意义

目的探讨生长相关蛋白(GAP-43)和脑源性神经营养因子(BDNF)受体TrkB基因在匹罗卡品致疒间大鼠海马的表达及其意义.方法应用原位杂交组织化学方法研究匹罗卡品(PILO)致疒间大鼠海马GAP-43及TrkB mRNA表达的变化.结果匹罗卡品致癫疒间持续状态后3～6小时,海马齿状回颗粒细胞、CA3区及CA1区锥体细胞层TrkB mRNA表达显著高于对照组(P<0.01或0.05);在慢性期第7～30天,呈现第2次表达增强.致疒间后6～12小时,正常状态下并不表达GAP-43的大鼠海马颗粒细胞其GAP-43 mRNA表达较对照组显著增高(P<0.01),24小时～7天表达减少,在癫疒间慢性期表达再次高于对照组.结论 GAP-43及TrkB是颞叶癫疒间病理基础--海马苔藓纤维出芽的重要分子机制;BDNF对苔藓纤维的作用部分是通过GAP-43实现的.     

脑源性神经营养因子与癫痫研究进展

癫痫发作后 ,脑内BDNF的表达升高 ,其在时间和地域分布上有一定规律 ,这与其维持神经元存活和再生的功能紧密相关 ;BDNF对癫痫动物模型的痫性发作有阻止作用 ;痫性发作后 ,BDNF的表达受到多种分子的影响     

脑源性神经营养因子诱导大鼠骨髓基质细胞成为神经干细胞及其分化作用的实验研究

目的探讨脑源性神经营养因子（BDNF）诱导大鼠骨髓基质细胞（BMSCs）成为神经干细胞及其分化作用。方法取大鼠BMSCs。分别以BDNF和BDNF＋RA（维甲酸）作为诱导物诱导，于诱导3d、7d后行巢蛋白（Nestin）、神经元特异烯醇化酶（NSE）、胶质纤维酸性蛋白免疫细胞化学染色。结果后BDNF和BDNF＋RA诱导组均有大量Nestin染色阳性细胞，BDNF＋RA组阳性率高于BDNF组（P〈0．01）。NSE、GFAP免疫阳性细胞在诱导3d后也有少量表达。诱导7d后BDNF和BDNF＋RA诱导组Nestin阳性细胞明显减少．与诱导3d后比较差异有显著性（P〈0．01），而NSE、GFAP阳性细胞敷增多，与诱导3b比较差异有显著性（P〈0．01），且BDNF＋RA组阳性率高于BDNF组（P〈0．01）。结论联合应用BDNF与RA可提高BMscs神经转化．并促进其向神经元及星形胶质细胞细胞分化。     

顽固性颞叶癫痫患者海马或颞叶BDNF及其受体TrkB的测定

目的检测脑源性神经营养因子(BDNF)及其受体酪氨酸激酶B受体(TrkB)在难治性颞叶癫痫(TLE)患者颞叶和/或海马中的含量,探讨其在癫痫发病机制中的作用。方法选取经手术治疗的82例难治性TLE患者术中切除的海马或颞叶脑组织,用免疫组化方法对BDNF及其受体TrkB含量进行检测,并与11例对照进行比较。结果在难治性TLE患者中,BDNF在颞叶和海马中含量明显增加(分别P<0.05,P<0.01),且海马中含量明显高于颞叶(P<0.01);TrkB在颞叶和海马中含量显著增加(P<0.01),且海马中含量高于颞叶(P<0.05)。结论难治性TLE患者海马和颞叶中BDNF和TrkB含量增高,可能在癫痫发生、发展中起重要作用。     

Neuronal injury and brain-derived neurotrophic factor expression in a rat model of amygdala kindling seizures Differences in brain regions and kindling courses

BACKGROUND:Studies have demonstrated that brain-derived neurotrophic factor (BDNF) has a dual effect on epilepsy. However, the relationship between epilepsy-induced brain injury and BDNF remains poorly understood.OBJECTIVE:According to ultrastructural and molecular parameters, to detect the degree of neuronal injury and BDNF expression changes at different brain regions and different kindling times to determine the effects of BDNF on epilepsy-induced brain injury.DESIGN, TIME AND SETTING:A randomized, controlled, animal experiment based on neuropathology and molecular biology was performed at the Department of Physiology and Department of Pathology, Basic Medical College of Jilin University in 2003.MATERIALS:UltraSensitiveTM SP kit for immunohistochemistry (Fuzhou Maxim Biotechnology, China), BDNF antibody (concentrated type, Wuhan Boster Biological Technology, China), JEM-1000SX transmission electron microscopy (JEOL, Japan), and BH-2 light microscope (Olympus, Japan) were used in the present study.METHODS:Wistar rats were randomly assigned to control (n = 6), sham-surgery (n = 6), and model (n = 60) groups. The control group rats were not treated; an electrode was embedded into the amygdala in rats from the sham-surgery and model groups; an amygdala kindling epilepsy model was established in the model group.MAIN OUTCOME MEASURES:Pathological changes in the temporal lobe and hippocampus were observed by light and electron microscopy at 1, 3, 7, 14, and 21 days following kindling, and BDNF expression in the various brain regions was determined by immunohistochemistry.RESULTS:In the model group, temporal lobe cortical and hippocampal neurons were swollen and the nuclei were laterally deviated. There were also some apoptotic neurons 3 days after kindling. The nucleoli disappeared and the nuclei appeared broken or lysed, as well as slight microglia hyperplasia, at 7 days. Electron microscopic observation displayed chromatin aggregation in the nuclei and slight mitochondrion swelling 3 days after kindling. Injury changes were aggravated at 7 days, characterized by broken cytoplasmic membrane and pyknosis. With the development of seizure, the number of BDNF-positive neurons in the hippocampus and temporal lobe increased and peaked at 7 days. Moreover, hippocampal and cortical temporal lobe injury continued. Following termination of electrical stimulation after 7 days of kindling, BDNF expression decreased, but continued to be expressed, up to 21 days of kindling. In addition, the number of temporal and hippocampal BDNF-positive neurons was greater than the control group.CONCLUSION:Brain injury and BDNF expression peaked at 7 days after kindling, and hippocampal changes were significant.     

Physical exercise alters the activation of downstream proteins related to BDNF‐TrkB signaling in male Wistar rats with epilepsy

There are a considerable number of studies concerning the behavioral effects of physical exercise on the epileptic brain; however, the intracellular signaling mechanisms involved remain unclear. We investigated the effects of aerobic exercise on hippocampal levels of brain‐derived neurotrophic factor (BDNF), expression of its receptor tropomyosin receptor kinase B (TrkB), and activation of intracellular proteins related to BDNF‐TrkB signaling in male Wistar rats with pilocarpine‐induced epilepsy. Thirty days after the first spontaneous seizure, rats from the exercise group undertook a 30‐day physical exercise program on the treadmill. Thereafter, BDNF levels, expression of TrkB, and activation of intracellular proteins were quantified by enzyme‐linked immunosorbent assay, Western blotting, and multiplex assay, respectively. Statistical analyses were conducted using nonparametric tests. Rats with epilepsy presented decreased BDNF levels compared with control rats. BDNF levels increased significantly in the exercise group compared with the epileptic and control groups. Expression of full‐length and truncated TrkB was increased in rats with epilepsy, and physical exercise restored its expression to control levels. RAC‐alpha serine/threonine‐protein kinase, mammalian target of rapamycin, and extracellular signal‐regulated kinase activation were reduced in rats with epilepsy, and exercise increased activation compared with control and epilepsy groups. Increased cAMP response element binding protein activation was observed in the exercise group compared with the epilepsy group. Our findings indicate that the beneficial effects of exercise in the epileptic brain can be in part related to alterations in the activation of proteins related to the BDNF‐TrkB signaling pathway.     

杏仁核点燃癫痫鼠GAD67mRNA的表达

目的 探讨大鼠杏仁核点燃癫痫后脑组织谷氨酸脱羧酶（GAD）mRNA的表达及其在癫痫发作后表达变化的意义。方法 通过建立与人类癫痫发生,形成具有高度相似性的杏仁核点燃大鼠癫痫模型。采用原位杂交技术检测癫痫鼠颞叶及海马组织不同点燃时程GAD67mRNA表达。结果 点燃后1d,GAD67mRNA表达增多并且表达信号增强,至7d时达高峰,以后表达逐渐下降,但在点燃后49d,表达仍高于正常,与对照组及手术对照组相比有统计学差异。结论 在慢性癫痫发作中,GABA能神经元的活性增强,考虑是由于癫痫过程中兴奋性增强,引起GABA能神经元抑制功能代偿性增加的结果,即癫痫发作后GABA能神经元介入的抑制功能代偿性增加的,这可能是机体内源性抗癫痫机制增强的一种反应。     

Delayed kindling development after rapidly recurring seizures: relation to mossy fiber sprouting and neurotrophin, GAP-43 and dynorphin gene expression

Development of kindling and mossy fiber sprouting, and changes of gene expression were studied after 40 seizures produced during about 3 h by electrical stimulation every 5 min in the ventral hippocampus. As assessed by 5 test stimulations, enhanced responsiveness was present already after 6–24 h but from 1 week post-seizure increased gradually up to 4 weeks without additional stimuli. Sprouting of mossy fibers in the dentate gyrus was demonstrated only at 4 weeks with Timm's staining. In situ hybridization showed a transient increase (maximum at 2 h) of brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), TrkB and TrkC mRNA levels and reduction (maximum at 12–24 h) of neurotrophin-3 (NT-3) mRNA expression in dentate granule cells after the seizures. In addition, BDNF mRNA levels were elevated in CAI and CA3 regions, amygdala and piriform cortex. Marked increases of mRNA for growth-associated protein (GAP-43), with maximum expression at 12–24 h, were observed in dentate granule cells and in amygdala-piri-form cortex. Dynorphin mRNA levels showed biphasic changes in dentate granule cells with an increase at 2 h followed by a decrease at 24 h. No long-term alterations of gene expression were observed. These findings indicate that increased responsiveness develops rapidly after recurring seizures but that the kindled state is reached gradually in about 4 weeks. Mossy fiber sprouting occurs in parallel to epileptogenesis and may play a causative role. Short-term changes of neurotrophin and Trk, GAP-43 and dynorphin mRNA levels and the assumed alterations of the corresponding proteins could trigger structural rearrangements underlying kindling but might also contribute to the initial increase of seizure susceptibility.     

戊四氮点燃癫(癎)大鼠海马巢蛋白和骨形成蛋白-4的表达研究

目的观察巢蛋白(nestin)和骨形成蛋白4(BMP4)基因在戊四氮(PTZ)点燃癫大鼠海马中的表达,并探讨两者与癫发病机制的关系。方法将81只成年雄性SD大鼠随机分为实验组(n=54)和对照组(n=27)。实验组采用PTZ点燃癫大鼠,按点燃中的不同时相点,又随机分为9组。用免疫组化技术、地高辛标记特异性寡核苷酸探针原位杂交组织化学技术,观察海马nestin和BMP4表达的变化。结果nestin阳性细胞在PTZ注射后3d开始出现在齿状回、CA3区和CA1区,到7d达到高峰,以后逐渐减少。BMP4在PTZ注射后7d开始增多,在点燃后1d达到高峰,以后逐渐减少,主要分布在齿状回、CA3区和CA1区。结论PTZ点燃可引起海马内星形胶质细胞增生、活化和神经发生,这可能是癫海马组织胶质化、神经元可塑性的病理基础;BMP4可能在PTZ癫形成过程中起重要作用。     

Suppressed Epileptogenesis in BDNF Mutant Mice

Kindling is an animal model of epilepsy in which repeated electrical stimulations lead to progressive and permanent amplification of seizure activity, culminating in generalized convulsions. Each brief period of seizure activity during kindling epileptogenesis causes a marked, transient increase of the synthesis of brain-derived neurotrophic factor (BDNF) in cortical and hippocampal neurons. We find that the development of kindling is markedly suppressed in mice heterozygous for a deletion of the BDNF gene. In contrast, the maintenance of kindling is unaffected. The mutant mice show lower levels of BDNF mRNA in cortical and hippocampal neurons after seizures than do wild-type mice. Hippocampal mossy fiber sprouting is augmented in BDNF mutants but there are no other morphological abnormalities. These results show that BDNF plays an important role in establishing hyperexcitability during epileptogenesis, probably by increasing efficacy in stimulated synapses.     

Increase in BDNF-mediated TrkB signaling promotes epileptogenesis in a mouse model of mesial temporal lobe epilepsy

Mesio-temporal lobe epilepsy (MTLE), the most common drug-resistant epilepsy syndrome, is characterized by the recurrence of spontaneous focal seizures after a latent period that follows, in most patients, an initial insult during early childhood. Many of the mechanisms that have been associated with the pathophysiology of MTLE are known to be regulated by brain-derived neurotrophic factor (BDNF) in the healthy brain and an excess of this neurotrophin could therefore play a critical role in MTLE development. However, such a function remains controversial as other studies revealed that BDNF could, on the contrary, exert protective effects regarding epilepsy development. In the present study, we further addressed the role of increased BDNF/TrkB signaling on the progressive development of hippocampal seizures in the mouse model of MTLE obtained by intrahippocampal injection of kainate. We show that hippocampal seizures progressively developed in the injected hippocampus during the first two weeks following kainate treatment, within the same time-frame as a long-lasting and significant increase of BDNF expression in dentate granule cells. To determine whether such a BDNF increase could influence hippocampal epileptogenesis via its TrkB receptors, we examined the consequences of (i) increased or (ii) decreased TrkB signaling on epileptogenesis, in transgenic mice overexpressing the (i) TrkB full-length or (ii) truncated TrkB-T1 receptors of BDNF. Epileptogenesis was significantly facilitated in mice with increased TrkB signaling but delayed in mutants with reduced TrkB signaling. In contrast, TrkB signaling did not influence granule cell dispersion, an important feature of this mouse model which is also observed in most MTLE patients. These results suggest that an increase in TrkB signaling, mediated by a long-lasting BDNF overexpression in the hippocampus, promotes epileptogenesis in MTLE.