脑源性神经营养因子与癫痫

癫痫发作可诱导海马内脑源性神经营养因子(BDNF)水平上调,进而激活海马门区及CA3区腔隙层的TrkB受体,通过促进兴奋性神经递质释放等效应加强海马通路尤其是苔状纤维的兴奋性突触传递,从而导致持续的高度兴奋状态;而阻断BDNF信号转导通路则可抑制癫痫发生.提示BDNF在癫痫发作过程中具有重要作用,进一步阐明其细胞分子机制将为探索癫痫治疗手段提供新途径.     

脑源性神经营养因子及其在中枢神经损伤修复中的作用

脑源性神经营养因子(BDNF)属于神经营养因子家族成员,与原肌球蛋白相关激酶B(trkB)受体相结合调节神经细胞的生存,生长以及突触传递。BDNF基因具有多个启动子及调节元件,其表达受神经活动和多种激素水平的调控。当大脑因外伤、缺血、压力等原因受损时,BDNF在中枢神经系统中表达增加,通过延缓凋亡、促进新生及增强突触传递等方法使受损神经细胞得以修复。本文对BDNF基因、BDNF表达的调控、BDNF的分子结构及其受体、BDNF的信号传导等做了介绍,阐述了BDNF在中枢神经损伤修复中的作用。     

灵芝孢子粉对癫痫大鼠脑组织细胞色素C、线粒体钙、HSP70和BDNF的影响

目的: 研究灵芝孢子粉对癫痫大鼠脑组织超氧化物歧化酶(SOD)、丙二醛(MDA)、总抗氧化能力(T-AOC)、细胞色素C、热休克蛋白70(HSP70)、线粒体Ca²⁺和脑源性神经营养因子(BDNF)的影响,探讨灵芝孢子粉对癫痫大鼠脑细胞的保护作用机制。方法: 用亚惊厥剂量的戊四氮(PTZ)复制癫痫慢性模型,采用火焰原子吸收法测定脑组织线粒体Ca²⁺的含量,分光光度计比色法测定SOD的活性、MDA和细胞色素C含量,免疫组织化学方法检测HSP70和BDNF的表达情况。结果: 与癫痫模型组相比,灵芝孢子粉组线粒体内细胞色素C、线粒体Ca²⁺的含量和HSP70的表达显著增高,而胞浆内细胞色素C含量则明显降低;脑组织SOD和T-AOC的活性明显增加,而MDA含量明显降低。大脑皮质和海马区BDNF阳性细胞数癫痫模型组明显高于正常对照组 (P<0.05); 灵芝孢子粉组皮质和海马区BDNF阳性神经元数目进一步增多,与癫痫模型组相比,差异显著(P<0.05)。结论: 灵芝孢子粉能明显降低癫痫发作对脑细胞线粒体造成的损伤,其作用机制可能是通过清除自由基、增强脑组织的抗氧化能力,从而减轻自由基对线粒体膜的损伤作用,恢复线粒体的能量代谢,减轻脑细胞的损伤与凋亡。     

自发性高血压鼠脑底动脉NPY mRNA的表达及其意义

为探讨高血压大鼠脑血管神经肽Y(neuropeptide Y,NPY)在高血压时期脑血管的神经源性调节作用及其在高血压的发生和发展中的作用,本研究应用逆转录-聚合酶链反应(RT-PCR)和免疫印迹(Western blotting)技术,检测自发性高血压大鼠脑基底动脉NPY mRNA和NPY的表达变化。结果显示:自发性高血压大鼠脑基底动脉NPY mRNA和NPY的表达均较正常血压鼠明显增加。本研究结果提示NPY在自发性高血压大鼠脑血管的神经源性调节以及在高血压的发生和发展中可能起重要作用。     

听源性惊厥点燃后听觉核团和前脑结构内一氧化氮合酶阳性神经元的形态学观察

为探讨一氧化氮在听源性惊厥点燃中的作用．用NADPH-d组织比学方法和体视学分析,研究厂Wistar种系的听源性惊厥易感大鼠（P77PMC）惊厥和点燃后听觉核团内NOS阳性神经元的分布及差异。结果显示：（1）P77PMC大鼠一次惊厥后,听觉核团和前脑结构内可见广泛的NOS阳性神经元,其分布类似于正常大鼠;（2）点燃后,听觉核团和前脑结构内NOS染色增深,NOS阳性神经元增加。特别是在下丘和嗅周皮质．除NOS阳性神经元明显增多外．其分布亦发生改变。本研究提示,听源性惊厥可诱导NOS表达增加,这种增加可能对于保持神经元增高的易感性有关。     

听源性惊厥上调惊厥易感大鼠脑内NR1基因的表达

N-甲基-D-门冬氨酸受体（NMDA或NR）功能的变化与癫痫的发生和发展密切相关．本文用原位杂交技术探讨了遗传癫痫易感大鼠P77PMC惊厥后不同时间NRI亚基基因表达状况，证明：大脑皮层，海马齿状回，CA1、CA2、CA3及下丘NR1mRNA表达呈时间依赖性增高，下丘在惊厥后2h即出现NR1mRNA高表，而大脑皮层和海马各区域24h达高峰．听源性惊厥后这些区域NR1mRNA表达的上调可能与神经网络兴奋性增高及癫痫易感性的保持有关。     

听源性惊厥点燃诱导新皮质内c-fos和BDNF变化的研究

为探讨前脑结构参与听源性惊厥点燃过程的神经化学机制 ,本研究以 c-fos基因表达作为神经元功能活动的标志 ,采用免疫细胞化学方法 ,对新皮质内参与听源性惊厥点燃过程的神经元的分布状况进行了观察 ,并对相关区域内脑源性神经营养因子表达水平的变化进行了分析。结果显示 ,单次听源性惊厥发作后 ,新皮质内仅有少量散在的 c-fos阳性神经元存在 ;听源性惊厥点燃后 ,额、顶、枕及颞叶皮质内出现大量 c-fos阳性神经元。点燃后额叶及顶叶皮质内脑源性神经营养因子免疫阳性产物的校正光密度值显著增高。结果表明 ,新皮质内大量神经元参与听源性惊厥点燃过程 ,脑源性神经营养因子表达增强很可能是其中的机制之一。     

不同年龄高血压鼠脑底动脉神经肽Y能神经纤维的分布

目的 :为了阐明不同年龄高血压鼠脑动脉神经肽Y(NPY)能神经的分布 ,探索高血压与脑动脉NPY能神经分布的年龄相关性。方法 :应用免疫组化法和神经交点计数法 ,对 12只不同年龄高血压鼠脑动脉NPY能神经纤维分布进行观察。结果 :在 6周龄高血压鼠大脑前动脉 (ACA)和大脑中动脉 (MCA)壁上均见黑色NPY纤维 ,较细 ,曲线状 ,以纵行分布为主 ;在 15周龄高血压鼠ACA和MCA壁纤维密度较高 ,纤维走行以环行为主 ;在 3 0周龄高血压鼠ACA和MCA壁纤维走行以网状为主 ,纤维密度较 6周龄和15周龄鼠增高 ,三个年龄组纤维密度依次为 :3 0周龄鼠 >15周龄鼠 >6周龄鼠。结论 :高血压鼠脑底动脉NPY能神经纤维密度随年龄增加而增高 ,纤维走行由纵行转变成环行、网状分布。提示高血压鼠呈年龄相关性增加的血压可能与高血压鼠脑血管呈年龄相关性增加的NPY能神经相关。     

吗啡慢性处理及戒断后不同时期大鼠海马脑源性神经营养因子与trkB表达的变化

目的:观察吗啡慢性处理及戒断后不同时期大鼠海马内脑源性神经营养因子(BDNF)与trkB的表达.方法: 实验组雄性成年SD大鼠以剂量递增的方法连续腹腔注射吗啡10d,每天2次.动物在戒断后0、1、7、14d和21d处死.对照组动物注射等量生理盐水,按同样方法处理.用免疫组织化学方法(ABC法)检测海马CA1区BDNF与trkB的表达.用Motic 3.2图像分析系统测定免疫阳性产物的平均光密度值.结果: 实验组BDNF免疫阳性产物的平均光密度值在戒断后0、1、7、14d和21d分别低于相应对照组,差异具有统计学意义,以戒断后14d下降最为明显.实验组trkB免疫阳性产物的平均光密度值在戒断后0、1、7、14d和21d分别也低于相应对照组,差异具有统计学意义.结论: 大鼠慢性吗啡成瘾及戒断后不同时间点BDNF与trkB在海马CA1区的表达明显下降,这种下降可能与大鼠吗啡成瘾及戒断后不同时期的行为学变化有关.     

脑源性神经营养因子转基因成纤维细胞的构建与检测

目的:构建大鼠脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)基因修饰的成纤维细胞(fibroblasts FBs).方法:真核表达载体pcDNA3/BDNF由昆明医学院神经科学研究所提供.FBs取自胎鼠.pcDNA3/BDNF重组质粒载体以阳离子脂质体Lipofect...     

大鼠海马CA1和CA3区发育过程中酪氨酸激酶受体B的分布

为了观察脑源性神经营养因子的特异性受体—酪氨酸激酶受体 B在发育过程中的大鼠海马 CA1和 CA3区的分布 ,本研究使用免疫组织化学 A BC法研究了生后几个时间段的酪氨酸激酶受体 B的分布特点。结果表明 :其免疫阳性产物仅出现在神经元胞体中且只位于胞浆 ,胶质细胞中未见分布。生后零天组偶见免疫阳性细胞 ;生后 5天组免疫阳性细胞较生后 0天组明显增多 ,但分布也尚较少 ;生后 10、15、2 0、30天 4组免疫阳性细胞呈明显的逐渐增多趋势。成年组的免疫阳性细胞与生后 30天组无明显差别。本实验结果提示 :发育早期大鼠海马 CA1和 CA 3区锥体细胞产生酪氨酸激酶受体 B,并通过对它的分泌调节 ,控制脑源性神经营养因子对神经元的作用 (突触的发生、发育、维持及神经元损伤后修复等     

Age-related changes in brain-derived neurotrophic factor and tyrosine kinase receptor isoforms in the hippocampus and hypothalamus in male rats

A large amount of aging individuals show diminished cognitive and endocrine capabilities. The main brain areas involved in these changes are the hippocampus and hypothalamus, two regions possessing high plasticity and implicated in cognitive and endocrine functions, respectively. Among neurotrophins (considered as genuine molecular mediators of synaptic plasticity), brain-derived neurotrophic factor (BDNF) exhibits in adult rats, the highest concentrations in the hippocampus and hypothalamus. Most of neuronal effects of BDNF are mediated through high-affinity cell surface BDNF tyrosine kinase receptors (TrkB). Different TrkB isoforms are issued by alternative splicing of mRNA encoding for TrkB (trkB mRNA) generating at least three different TrkB receptors with different signaling capabilities. The goal of this study was to examine simultaneously the expression (mRNAs and proteins) of BDNF and its three specific receptors, in the hippocampus and hypothalamus throughout lifespan in rats. We observed that BDNF essentially increased during the first 2 postnatal weeks in the hippocampus and hypothalamus, with no close correlation to its mRNA levels. In these regions, mRNA encoding for BDNF full-length catalytic receptor (trkB.FL mRNA) showed no important changes throughout life but of the mRNA truncated forms of TrkB receptors (trkB.T1 mRNA and trkB.T2 mRNA) trkB.T1 mRNA strongly increased after birth, then remaining stable during aging. trkB.T2 mRNA gradually decreased from 1 postnatal week becoming undetectable in the hippocampus in old-rats. Proteins issued from these mRNAs showed substantial quantitative modifications with aging. From 2 months old, the BDNF full-length catalytic receptor (TrkB.FL) gradually and significantly decreased in the hippocampus and the hypothalamus. Of the truncated forms of TrkB receptors (TrkB.T1 and TrkB.T2) TrkB.T1, which is essentially localized in glial cells, significantly increased from the first postnatal week in the hippocampus and in the hypothalamus, remaining stable during aging but reduced in old rats. TrkB.T2 which similarly to TrkB.FL has a neuronal localization also gradually decreased in the hippocampus and in the hypothalamus throughout lifespan. These reductions were significant at 21 and 30 days old, respectively. All the changes reported here could contribute to the reduced plasticity of these regions observed in old rats.     

促肾上腺皮质激素对慢性痛大鼠痛行为和海马内BDNF、CRF水平的影响

目的与方法:采用痛行为评分方法、免疫组化和原位杂交技术,观察促肾上腺皮质激素(ACTH)对完全福氏佐剂所致的关节炎大鼠海马内脑源性神经营养因子(BDNF)及其功能性受体trkB和促肾上腺皮质激素释放激素(CRH)水平的影响。结果:关节炎大鼠的痛行为评分显著高于正常对照组,同时注射侧对侧海马内BDNF免疫活性(IR)神经元、CRHmRNA阳性神经元和BDNF/CRHmRNA双染神经元数在注射佐剂后 2 4h显著高于正常对照组,而腹腔注射ACTH(2 5IU/kg或 12 5IU/kg)后,上述指标显著低于关节炎组;摘除双侧肾上腺后,腹腔注射ACTH的关节炎大鼠对侧海马内BDNF-IR、CRHmRNA阳性神经元和BDNF/CRHmRNA双染神经元数明显高于未摘除肾上腺的关节炎组。结论:海马内的BDNF和CRH参与慢性痛的调制,ACTH能抑制海马内BDNF和CRH的升高而产生镇痛作用,肾上腺对ACTH发挥其功能起决定性作用.     

BDNF Meditated trkB and Synapsin I Changes within the Hippocampus after Mild Traumatic Brain Injury in Rat:Reflections of Injury-induced Neuroplasticity

1 IntroductionTraumatic brain injury (TBI) can produce chronic cognitive learning/memory deficits that are thought to be mediated, in part, by impaired hippocampal function. Brain-derived neurotrophic factor (BDNF), its signal transduction receptor trkB and its downstream effector synapsin I are involved in this period. BDNF, trkB and the slope of field excitatory post-synaptic potential(fEPSP) were measured in the hippocampus of rat after fluid percussion brain injury (FPI). Isofluorane anaesthe- tizeed 50...     

Spatial memory training modifies the expression of brain-derived neurotrophic factor tyrosine kinase receptors in young and aged rats

Aging leads to alterations in the function of the hippocampus, a brain structure largely involved in learning processes. This study aimed at examining the basal levels and the impact of a learning-associated task on brain-derived neurotrophic factor (BDNF), on BDNF full-length catalytic receptor (TrkB.FL) and on the truncated forms (TrkB.T1 and TrkB.T2) receptor expression (mRNA and protein) in the hippocampus of young (2-month-old) and aged (24-month-old) Wistar rats. Spatial memory was evaluated using a water-maze procedure involving visible and invisible platform location learning. Aged rats showed higher latencies during the first two training days but rapidly exhibited learning performances similar to patterns observed with young rats. Real-time PCR measurements showed that aged rats had significantly higher levels of trkB.FL mRNAs than young rats under basal conditions. In situ hybridization analysis indicated that the highest level of trkB.FL mRNA (mRNA encoding for TrkB.FL receptor) was noted in the dentate gyrus, and in the CA2 and CA3 hippocampal layers. In contrast, there was no marked difference in trkB.T1 signal in any hippocampal region. Training induced a significant reduction in trkB.FL mRNA levels solely in aged rats. In contrast, in young and aged rats, trkB.T2 mRNA levels were significantly increased after training. Measurements of proteins revealed that learning significantly increased TrkB.FL content in aged rats. Untrained aged rats presented higher levels of BDNF and brain-derived neurotrophic factor precursor (proBDNF) proteins than young rats. Training strongly increased precursor BDNF metabolism in young and aged rats, resulting in increased levels of proBDNF in the two groups but in old rats the mature BDNF level did not change. This study shows that Wistar rats present age-related differences in the levels of BDNF and TrkB isoforms and that spatial learning differentially modifies some of these parameters in the hippocampus.     

去脑皮层血管对大鼠前脑大细胞基底核AChE、ChAT、BDNF、trkB及其mRNA表达的影响

本研究采用去除大鼠皮层血管建立的血管性痴呆模型。去除皮层血管后 ,发现大鼠前脑大细胞基底核胆碱能神经元的ACh E、Ch AT、BDNF、trk B及其 m RNA的表达明显降低。结果说明 ,去皮层血管后造成的大细胞基底核的损害是继发皮质损害的逆行性变性 ,大鼠去皮层血管后 ,皮质、海马等处神经元靶源性的 BDNF、trk B及其 m RNA的表达降低 ,逆行性运输到大细胞基底核的胆碱能神经元的 BDNF减少 ,导致大细胞基底核神经元的变性、坏死     

惊厥对神经元缝隙连接蛋白基因表达的影响

神经元之间的缝隙连接蛋白Cx32是形成电突触的结构基础,电突触参与惊厥时神经元的同步化放电过程。为探讨惊厥对脑内神经元Cx32基因表达的影响,以遗传性癫痫易感大鼠P77PMC为模型,采用原位杂交的方法观察P77PMC大鼠听源性惊厥后脑内Cx32基因表达的变化。原位杂交结果显示：惊厥后在大脑皮层,海马脑区Cx32mRNA表达呈时间依赖性上调,惊厥后4h表达量明显增加,24h达高峰,结果提示：惊厥能上调神经元Cx32mRNA表达,从而可能使神经元之间的电突触联系增加,有利于神经元的同步化放电,加重惊厥的发生发展。     

Neuropeptide Y and somatostatin participate differently in the seizure-generating mechanisms following trimethyltin-induced hippocampal damage

Trimethyltin (TMT) is an organic metal known to induce neuronal degeneration in the hippocampus, and abnormal behavior characterized by seizures, increased aggression and memory deficits. We administered TMT to rats and studied the changes of neuropeptide Y (NPY) and somatostatin (SOM) in the hippocampus. Phenobarbital (PB) was administered as an anticonvulsant to assess the effect of seizures on neuropeptide expressions in both dorsal and ventral hippocampus. Histochemically, NPY-immunoreactivity increased 4 days after TMT treatment in the hilus of the hippocampus, then progressively decreased and dropped to a level below control 16 days after TMT treatment. Detection of NPY mRNA by in situ hybridization preceded the detection of NPY by immunohistochemistry. NPY mRNA signals increased in the hilus 2 days after TMT treatment. SOM-immunoreactivity also increased in the hilus of the hippocampus 2 days after TMT treatment, then decreased rapidly to a normal level. Similar changes in SOM mRNA were demonstrated by in situ hybridization. PB treatment significantly inhibited changes of NPY in terms of both immunoreactivity and mRNA expression; however, the same treatment failed to affect changes in SOM expression. This suggests that NPY and SOM act by different mechanisms in TMT-induced neurodegeneration.     

遗传性P77PMC癫痫大鼠海马基因表达谱的研究

目的利用cDNA表达阵列构建遗传性癫痫大鼠海马基因表达谱,寻找其中的差异表达基因,为从分子水平探讨癫痫的发病机理打下基础。方法采用32P-α-dATP逆转录标记探针与cDNA阵列杂交,构建P77PMC大鼠和Wistar大鼠海马基因表达谱,用图象分析仪分析两者基因表达谱差异。结果在P77PMC大鼠海马中共发现有15个差异表达基因,其中12个基因表达上调,3个基因表达下调。并用逆转录-聚合酶链反应进一步证实了结果的可靠性。结论P77PMC大鼠与正常Wistar大鼠海马中存在多个差异表达基因,这些差异表达的基因可能在癫痫的发生中具有重要作用。