脑源性神经营养因子在大鼠脑缺血再灌注损伤过程中基因表达的变化

目的 :观察脑缺血再灌注损伤后脑皮层、梗塞区和海马神经元脑源性神经营养因子 (BDNF)水平的变化 ,及与脑病理变化的关联性 ;探讨 BDNF在脑缺血再灌注损伤中的可能作用机理。方法 :线栓法复制大鼠大脑中动脉脑缺血再灌注模型 ,原位核酸分子杂交检测脑不同区域 BDNFm RNA,图象分析间接定量其水平。结果 :1.脑缺血及缺血再灌注均能诱导双侧脑皮层、海马和梗塞区及其对侧相应区神经元 BDNFm RNA水平增高。2 .梗塞区因缺血损伤过重 ,神经元 BDNFm RNA水平增高的幅度小。 3.再灌注后神经元 BDNFm RNA的水平继续升高 ;其变化规律在不同脑区大致相似。 4.神经元 BDNFm RNA基础水平与神经元抗损伤力呈正相关。结论 :脑缺血及缺血再灌注损伤均导致双侧大脑 BD-NFm RNA表达的变化 ,BDNFm RNA水平的提高能增强神经元的抗损伤能力。     

阿司匹林促进大鼠缺血脑组织脑源性神经营养因子的表达

目的:探讨不同剂量阿司匹林(Asp)对脑缺血/再灌注(CI/RP)损伤大鼠的神经保护作用及其对脑源性神经营养因子(BDNF)表达的影响。方法:采用线栓法建立大鼠大脑中动脉CI/RP模型,对CI/RP后大鼠进行肢体神经功能缺损评分:1~3分的48只大鼠入选。入选大鼠分为对照组、Asp小剂量组(20 mg.kg-1)、Asp中剂量组(80 mg.kg-1)和Asp大剂量组(320 mg.kg-1),于CI/RP术后每日腹腔注射Asp或溶媒,并进行神经功能缺损评分,72 h后处死,测定脑梗死体积和BDNF免疫组化检测。结果:CI/RP后24、48和72 h各Asp组大鼠与对照组相比,神经缺损评分明显降低(P<0.05或P<0.01),梗死灶体积显著减小(P<0.01),缺血区域BDNF表达显著增加(P<0.05或P<0.01)。对BDNF表达的作用Asp大剂量组的作用并不优于Asp小剂量组和中剂量组。结论:Asp可以减少CI/RP大鼠的脑梗死体积;促进内源性BDNF的表达可能是其神经保护的机制之一,Asp对BDNF表达的作用并非随Asp剂量的加大而增强。     

脑缺血再灌注损伤过程中脑的病理变化与脑内脑源性神经营养因子的基因表达

目的 研究在脑缺血-再灌注损伤过程中，脑组织的病理变化与脑源性神经营养因子(brain derived neurotrophic factor，BDNF)基因表达之间的关系。方法 采用Zea longa线栓法创建局部脑缺血-再灌注模型。光镜下观察病理变化，原位寡核酸分子杂交检测在脑缺血-再灌注损伤过程中，脑的不同区域BDNF mRNA的表达，图像分析BDNF的间接定量水平。结果 (1)脑缺血和脑缺血再灌注均可导致BDNF mRNA在脑的广泛区域表达活跃；(2)损伤过重反而抑制BDNF mRNA的表达；(3)BDNF mRNA的表达具有组织差异性；(4)脑缺血-再灌注后，早期BDNF mRNA的表达水平即明显增加，12h达高峰。结论 BDNF的提高是一种保护性反应，脑缺血和脑缺血再灌注损伤均可以导致BDNF mRNA在脑的广泛区域表达水平明显提高，表达水平与局部神经元的抗损伤能力呈正相关，与病理改变呈负相关。     

脑源性神经营养因子与抑郁症的研究进展

海马结构和功能的改变涉及抑郁症的病理生理学过程，海马脑源性神经营养因子表达下调与海马结构和功能的改变密切相关，促进细胞凋亡可能参与慢性应激损伤海马。抗抑郁剂通过调节脑源性神经营养因子的表达逆转海马损伤而发挥治疗作用。     

亚低温对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活素、脑源性神经营养因子表达的影响

目的观察亚低温干预对局灶性脑缺血再灌注大鼠脑皮质神经元凋亡及存活累(Survivin)、脑源性神经营养因子(BDNF)表达的影响,探讨Survivin、BDNF在亚低温脑保护机制中的作用。方法采用线栓法制备成年雄性SD大鼠大脑中动脉闭塞(MCAO)局灶性脑缺血再灌注改良模型,将90只大鼠随机分为假手术组、常温缺血组和亚低温缺血组,缺血组分别于缺血3h再灌注3h、6h、12h、24h、48h、72h、7d处死,亚低温缺血组于缺血后10min实施全身亚低温持续3h。进行TUNEL染色及免疫组化染色,检测梗死灶周围皮质神经元凋亡数量和Sur-vivin、BDNF的表达水平。结果 (1)亚低温缺血组和常温缺血组于再灌注6h皮质区均出现TUNEL染色阳性细胞,72h达高峰,随后逐渐减少,两组内相邻时间点比较差异均有统计学意义(P<0.05);在相同时间点亚低温缺血组凋亡细胞数明显少于常温缺血组,两组间比较差异有统计学意义(P<0.05)。(2)亚低温缺血组于再灌注3hSurvivin、BDNF表达有所增加,BDNF于24h达高峰,Survivin于48h达高峰,随后表达逐渐降低,但7d时仍高于假手术组,常温缺血组表达趋势与之相似,两组各时间点Survivin、BDNF表达均高于假手术组,差异有统计学意义(P<0.05);除再灌注3h Survivin表达在亚低温缺血组与常温缺血组间无明显差异外,其余各时间点亚低温缺血组Sur-vivin、BDNF表达均高于常温缺血组,差异有统计学意义(P<0.05)。结论亚低温干预可抑制梗死灶周围脑皮质神经细胞凋亡,促进存活素及脑源性神经营养因子的表达,发挥脑保护作用。     

丁香酚吸嗅对MCAO模型大鼠脑源性神经营养因子的影响

目的研究丁香酚吸嗅对MCAO模型SD大鼠认知和记忆能力的行为学的影响,评价其对脑缺血后再灌注损伤的干预作用及其可能的作用机制。方法将80只SD雄性大鼠,随机分为正常组、模型组、丁香酚组和假手术组,每组20只。采用大脑中动脉内线栓阻断法(MCAO)制造大鼠局灶性脑缺血再灌注模型,缺血2 h后再灌注24 h。给予相应处理3 w后,大鼠行神经行为学评分后处死,取大脑行2,3,5-氯化三苯基四氮唑(TTC)染色,计算脑梗死容积百分比;Morris水迷宫实验检测学习记忆能力;并利用免疫组织化学染色法观察脑源性神经营养因子(BDNF)在海马CA3区的表达。结果丁香酚吸嗅组干预3 w后与模型组比较神经功能评分差异有显著性(P<0.01);TTC染色梗死面积明显减少(P<0.01),Morris水迷宫实验差异有显著性(P<0.05);海马CA3区BDNF的表达显著性增多。结论丁香酚吸嗅对MACO模型大鼠的损伤有明显的保护作用,其机制可能是提高脑内BDNF含量,调节脑区功能,从而达到对脑缺血再灌注损伤的防治作用。     

脑源性神经营养因子与抑郁症的研究进展

海马结构和功能的改变涉及抑郁症的病理生理学过程 ,海马脑源性神经营养因子表达下调与海马结构和功能的改变密切相关 ,促进细胞凋亡可能参与慢性应激损伤海马。抗抑郁剂通过调节脑源性神经营养因子的表达逆转海马损伤而发挥治疗作用     

脑源性神经营养因子对海马神经元NMDA受体功能下调的逆转作用

应用全细胞膜片钳技术研究BDNF对培养养海马神经元NMDA受体的调控作用。结果发现,培养18d的海马神经元NMDA诱发电流小,BDNF可快速、可逆地增加NMDA诱发电流,而培养10,14d的海马神经元NMDA诱发电流大,BDNF增强NMDA诱发电流不明显。本文结果提示BDNF对功能低下的海马神经元NMDA受体具有上调作用。     

脑源性神经营养因子对海马神经元NMDA受体功能下调的逆转作用

应用全细胞膜片钳技术研究BDNF对培养海马神经元NMDA受体的调控作用.结果发现,培养18d的海马神经元NMDA诱发电流小,BDNF可快速、可逆地增加NMDA诱发电流,而培养10,14d的海马神经元NMDA诱发电流大,BDNF增强NMDA诱发电流不明显.本文结果提示BDNF对功能低下的海马神经元NMDA受体具有上调作用.     

亚低温对局灶性脑缺血-再灌注大鼠脑皮质脑源性神经营养因子表达及神经元凋亡的影响

目的 观察局灶性脑缺血-再灌注后亚低温干预对大鼠脑源性神经营养因子表达及神经元凋亡的影响，并探讨脑源性神经营养因子在亚低温脑保护机制中的作用。方法 采用线栓法制备成年雄性SD大鼠左侧大脑中动脉闭塞局灶性脑缺血-再灌注改良模型，缺血时间2h。随机分为常温缺血组和亚低温缺血组。常温时大鼠脑温控制于36．5℃～37．5℃，肛温为35．9℃～36．9℃；亚低温时脑温维持于32．5℃～33．5℃，肛温为32．2℃～33．1℃。两组大鼠分别于脑缺血一再灌注及亚低温干预后2、6、24和72h进行神经功能缺损评分，并同时行三苯基氯化四唑（1TC）染色、HE染色、TUNEL染色、免疫组化染色及免疫组化与TUNEL双重染色，从而评估大鼠神经功能缺损状况；检测脑梗死体积及脑源性神经营养因子表达水平；观察组织病理学变化和神经元凋亡数量。结果 与常温缺血组相比，亚低温缺血组大鼠神经功能缺损评分低（P〈0．01），脑梗死体积小（P〈0．01），缺血灶周围脑皮质中的脑源性神经营养因子表达水平增高（P〈0．01），而且神经元凋亡数量少（P〈0．01）。在脑源性神经营养因子免疫组化染色呈阳性反应的神经元细胞核中，未发现TUNEL染色阳性者。结论 亚低温干预治疗可促进缺血灶周围的脑皮质对脑源性神经营养因子的表达，从而抑制神经元凋亡，减少大鼠脑梗死体积，改善神经功能缺损体征。     

雌激素对大鼠脑缺血后自发抑郁行为及缺血半暗带纹状体内脑源性神经生长因子的影响

目的：探讨雌激素对大鼠脑缺血后自发性抑郁行为的作用及对缺血半暗带纹状体内脑源性神经营养因子（BDNF）表达的影响。方法：应用大脑中动脉线栓术建立大鼠脑缺血模型。脑缺血模型大鼠随机分为对照组,脑卒中组,雌激素干预（皮下注射17β-雌二醇大豆油0.1 mL,×2周）组。观察脑缺血后及雌激素干预后抑郁行为学改变,检测缺血半暗带纹状体内BDNF表达。结果：脑缺血后,大鼠强迫游泳不动时间延长。雌激素组不动时间缩短,缺血半暗带BDNF阳性细胞数明显高于脑卒中组。结论：大鼠脑缺血后可以自发产生抑郁样症状,雌激素治疗可以改善这些症状,提高缺血半暗带BDNF表达可能为其治疗机制之一。     

大鼠局灶性脑缺血后再灌注期caspase—9 mRNA及Apaf—1mRNA表达的动态变化

目的探讨大鼠局灶性脑缺血后再灌注期caspase-9 mRNA及Apaf-1 mRNA表达的动态变化.方法采用线栓法制作大鼠局灶性脑缺血后再灌注模型,以逆转录聚合酶链式反应(RT-PCR)技术检测caspase-9 mRNA及Apf-1 mRNA的表达.结果缺血2 h后再灌注,缺血皮质中caspase-9 mRNA的表达在再灌注后24h达高峰,48h仍保持高水平,而Apaf-1 muRNA的表达无明显改变.结论局灶性脑缺血后再灌注48h内caspase-9 mRNA表达增强.     

红景天苷和脑源性神经营养因子与神经干细胞共移植对致鼠神经干细胞定向分化的研究

目的：探讨红景天苷和脑源性神经营养因子（BDNF）、神经干细胞（NSCs）共移植对致鼠NSCs定向分化影响。方法：将戊四氮致大鼠分为模型组、NSCs组、NSCs＋BDNF组和NSCs＋BDNF＋红景天苷组。取新生大鼠海马组织,将培养的NSCs与BDNF＋红景天苷＋BDNF和基础培养基分别移植至致鼠海马组织中,苏木精-伊红染色及免疫组化检测不同时间点5-溴脱氧尿嘧啶核苷（BrdU）、谷氨酸脱羧酶（GAD65）阳性细胞数,并观察大鼠行为学改变。结果：NSCs＋BDNF＋红景天苷共移植组与其他组比较,各时间点BrdU、GAD65阳性细胞数均增多（P〈0.05）。第3周开始,大鼠癫发作次数最少（P〈0.05）。结论：BDNF与红景天苷联合有利于神经干细胞向γ-氨基丁酸能神经元分化。两者联合移植至致鼠后能减少大鼠的癫发作次数。     

Expression of Ciliary Neurotrophic Factor and the Neurotrophins-Nerve Growth Factor,Brain-Derived Neurotrophic Factor and Neurotrophin 3-in Cultured Rat Hippocampal Astrocytes

Cultured astrocytes are known to possess a range of neurotrophic activities in culture. In order to examine which factors may be responsible for these activities, we have examined the expression of the genes for four known neurotrophic factors – ciliary neurotrophic factor (CNTF), nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin 3 (NT3) – in purified astrocyte cultures derived from neonatal rat hippocampus. Hippocampal astrocytes were found to express mRNA for three neurotrophic factors – CNTF, NGF and NT3 – at significantly higher levels than other cultured cell types or cell lines examined. BDNF messenger RNA (mRNA), however, was undetectable in these astrocytes. The levels of CNTF, NGF and NT3 mRNA in astrocytes were largely unaffected by their degree of confluency, while serum removal caused only a transient decrease in mRNA levels, which returned to basal levels within 48 h. Astrocyte-derived CNTF was found to comigrate with recombinant rat CNTF at 23 kD on a Western blot. Immunocytochemical analysis revealed strong CNTF immunoreactivity in the cytoplasm of astrocytes, weak staining in the nucleus, but no CNTF at the cell surface. NGF and NT3 were undetectable immunocytochemically. CNTF-like activity, as assessed by bioassay on ciliary ganglion neurons, was found in the extract of cultured astrocytes but not in conditioned medium, whereas astrocyte-conditioned medium supported survival of dorsal root ganglion neurons but not ciliary or nodose ganglion neurons. This conditioned medium activity was neutralized with antibodies to NGF. Astrocyte extract also supported survival of dorsal root ganglion and nodose ganglion neurons, but these activities were not blocked by anti-NGF. Part, but not all, of the activity in astrocyte extracts which sustained nodose ganglion neurons could be attributed to CNTF.     

散发性阿尔茨海默病患者血清脑源性神经营养因子的测定及临床意义

目的探讨散发性阿尔茨海默病(sporadic Alzhei mer disease,SAD)患者血清脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)变化及其临床意义。方法选择2004-11—2005-10作者医院门诊及住院SAD患者43例,其中轻度痴呆18例,中度痴呆19例,重度痴呆6例。对照组35例为同期体检者。采用酶联免疫吸附法(ELISA)测定外周血清BDNF水平。结果SAD组和对照组间性别(χ2=0.0042,P=0.9483)、年龄(t=0.38,P=0.7023)及血清BDNF水平(t=0.60,P=0.5528)差异均无统计学意义,轻、中、重度SAD组及对照组间血清BDNF水平比较亦无统计学意义(F=0.89,P=0.4526)。结论SAD患者外周血清BDNF水平无明显变化,血清BDNF水平不能作为SAD诊断的标志物,也不能反映痴呆的严重程度。     

Injury-induced Regulation of Ciliary Neurotrophic Factor mRNA in the Adult Rat Brain

Ciliary neurotrophic factor (CNTF) is a pleiotropic molecule that acts as a neurotrophic factor for a wide range of embryonic neurons as well as a differentiation factor for sympathetic neuroblasts and O2A progenitor cells in culture. CNTF messenger RNA (mRNA) is present at very low levels in the normal adult rat central nervous system (CNS), but is dramatically up-regulated after an aspiration lesion of dorsal hippocampus and overlying cortex, in the area coincident with glial scar. The increased level of CNTF mRNA in lesioned hippocampus is maximal by 3 days and is sustained for up to 20 days, the longest time point examined. In contrast, mRNA levels for brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) were slightly decreased during the same period. In situ hybridization experiments revealed that cells expressing CNTF mRNA were concentrated at the margin of the wound, and also present within the gelfoam which filled the lesion cavity. This distribution of CNTF-expressing cells corresponded very closely to that of cells expressing high levels of glial fibrillary acidic protein mRNA at the wound site. Paralleling the observed increase in CNTF mRNA, increased levels of CNTF-like neurotrophic activity were apparent in soluble extracts of the lesioned tissues. This neurotrophic activity for ciliary ganglion neurons was completely blocked by the addition of neutralizing antiserum against CNTF. Basic fibroblast growth factor, which has been shown by others to increase after a similar lesion paradigm (Frautschy et al., Brain Res. , 553 , 291–299, 1991), does not contribute appreciably to this trophic activity. We conclude that CNTF is markedly increased as a function of injury to the CNS and that its expression is most likely restricted to reactive astrocytes in the glial scar.     

Neurotrophic Factor Receptors and Their Signal Transduction Capabilities in Rat Astrocytes

Until recently, astrocytes were not considered as sites for neurotrophic factor action. We show here that, both in vivo and in vitro , astrocytes express receptors for two separate families of neurotrophic factors. In the intact adult rat CNS, astrocytes express the extracellular domain of the neurotrophin receptor TrkB and, in a more restricted population, the low-affinity nerve growth factor receptor p75^LNGFR. In the lesioned CNS, expression of the alpha component of the receptor for ciliary neurotrophic factor (CNTFRα) switches from a purely neuronal localization to cells in the glial scar at the edge of the wound. Using cultured hippocampal astrocytes as a model to address the functional status of these receptors, we have found only the truncated forms of TrkB and TrkC, which are incapable of signal transduction as measured by protein tyrosine phosphorylation or immediate early gene induction. In contrast, a fully functional CNTF receptor complex capable of signal transduction is present on cultured astrocytes. Thus, the neurotrophin receptors may act primarily to sequester or present the neurotrophins, whereas in the case of CNTF a functional response can be initiated within the astrocyte.     

Brain-Derived Neurotrophic Factor Improves Long-Term Potentiation and Cognitive Functions after Transient Forebrain Ischemia in the Rat

We investigated the effect of brain-derived neurotrophic factor (BDNF) on hippocampal long-term potentiation (LTP) and cognitive functions after global cerebral ischemia in the rat. After four-vessel occlusion, BDNF was administered via an osmotic minipump continuously over 14 days intracerebroventricularly. Electrophysiological experiments were performed 14 days after cerebral ischemia. Test stimuli and tetanization were delivered to the Schaffer collaterals of the hippocampus and field excitatory postsynaptic potentials (fEPSP) were recorded in the CA1 region. Cognitive impairment was analyzed repeatedly with a passive avoidance test, a hole-board test, and with an activity center on the same animal. In sham-operated animals, LTP was consistantly induced after delivering a tetanus (increase of initial slope of fEPSP to 173 +/- 12% of baseline; n = 6). After transient forebrain ischemia LTP could not be induced (117 +/- 4% of baseline; n = 7). In ischemic animals treated with BDNF, LTP could be induced (168 +/- 28% of baseline; n = 8). Transient forebrain ischemia resulted in a significant decrease in spatial discrimination performance but not of associative memory. The ratios for working memory (WM) and reference memory (RM) 15 days after ischemia were lower in the ischemic rats (n = 10) than in the sham-operated control animals (n = 10; WM: 22 +/- 6 vs 72 +/- 7; RM: 30 +/- 7 vs 72 +/- 5). Postischemic intracerebroventricular BDNF infusion increased both WM (63 +/- 4; n = 10) and RM (58 +/- 5; n = 10). The spontaneous locomotor activity did not differ significantly in the three groups. These data indicate a protective effect of BDNF for synaptic transmission and cognitive functions after transient forebrain ischemia.