微管相关蛋白Doublecortin在成年大鼠神经元前体细胞发生中的表达

目的:探索神经元前体细胞的微管相关蛋白Doublecortin(DCX)在成年大鼠神经元前体细胞发生中的表达,为神经元前体细胞的增殖和迁移研究提供理论及实验基础。方法:将大鼠脑组织行冰冻切片,采用免疫组化在光镜下观察DCX免疫阳性细胞的表达部位和形态特点。结果:神经元前体细胞的标志物DCX主要分布在4个神经发生相关区域:室下区、齿状回的粒下层、吻侧迁移流和嗅球。然而在皮质等无神经发生的区域只有极少量的DCX免疫阳性细胞。DCX免疫阳性细胞在形态上均呈梭形的胞体和单个的前导突起。结论:DCX免疫阳性细胞的形态符合神经元前体细胞的形态特征。DCX作为神经元前体细胞的标志物可以用来研究神经元前体细胞的增殖和迁移。     

脑室内注射重组BDNF腺病毒对大鼠海马神经发生的影响

目的 观察脑室内注射BDNF对海马神经发生的影响.方法 脑室内注射重组BDNF腺病毒4周后,Morris 水迷宫进行行为学检测,双标组化染色方法观察海马新生神经元数目的 变化.结果 与对照组相比,实验组大鼠空间学习和记忆能力明显增强(P<0.05);实验组大鼠海马DG区Brdu/DCX阳性神经元数目明显多于对照组(P<...     

慢性复合应激增强大鼠海马Doublecortin的表达

目的 探讨慢性复合应激性学习记忆增强大鼠海马齿状回(DG)新生神经元数量变化以及Doublecortin(DCX)在海马组织中表达的变化及其意义.方法 成年雄性大鼠随机分为复合应激组和正常对照组.复合应激组动物每天交替暴露于复合应激原中达6周.实验结束后,所有动物分别进行3d的Morris水迷宫测试,记录其学习和记忆成绩.运用免疫细胞化学方法观察海马DG新生神经元数量的变化,同时运用Western blotting和RT-PCR技术分别检测DCX在海马的表达及其mRNA水平的变化.结果 与对照组相比,复合应激组动物的学习与记忆成绩优于对照组(P＜0.05);其海马DG新生神经元数明显增多(P＜0.05);海马DCX蛋白的表达明显增加(P＜0.05);海马DCX mRNA水平明显上调(P＜0.05).结论 慢性复合应激致大鼠的学习与记忆能力增强,海马DG内DCX阳性细胞数增多,提示新生神经元数量增加是导致大鼠学习记忆能力增强的原因之一.     

慢性缺氧对大鼠行为和海马齿状回DCX阳性细胞的影响

目的:研究慢性低压性缺氧对大鼠行为和海马齿状回DCX阳性细胞的影响。方法:建立SD大鼠慢性低压性缺氧模型,通过开场实验和蔗糖饮水实验观察大鼠行为变化。取脑组织冰冻切片,用免疫荧光检测海马齿回神经元前体细胞标志物微管相关蛋白Doublecortin(DCX)检测海马齿状回DCX阳性细胞的变化。结果:与对照比较,慢性低压性缺氧大鼠体重,开场实验水平运动得分,垂直运动得分降低和蔗糖偏嗜度均明显降低(P0.01)。免疫荧光双标检测显示,慢性低压性缺氧大鼠海马齿状回颗粒下层(SGZ)DCX阳性细胞减少;DCX阳性细胞平均胞体周长(μm):实验组(151.2±16.1)明显大于对照组(132.8±14.5,P0.01);DCX阳性细胞突起平均长度(μm):实验组(21.7±7.3)明显大于对照组(15.2±5.6,P0.01)。结论:慢性低压性缺氧大鼠行为学上可发生明显改变,海马齿状回DCX阳性细胞再生能力减弱,提示缺氧导致该细胞再生损害可能是发生行为学改变的基础。     

立体定向移植骨髓间充质干细胞改善血管性大鼠的学习记忆能力

背景：大量的实验证明将骨髓间充质干细胞移植到复制的中枢神经系统疾病大鼠模型后,能迁移到损伤部位,表达神经细胞的潜在特性并且提高神经功能。 目的：验证骨髓间充质干细胞对拟人类血管性痴呆模型大鼠学习记忆障碍的改善作用。 方法：分离SD大鼠骨髓间充质干细胞,于细胞移植前掺入10 mg/L的BrdU进行标记。建立Wistar大鼠血管性痴呆样学习记忆障碍动物模型,随机分为模型组、假手术组与移植组。移植组致伤后第14天,通过立体定向途径移植骨髓间充质干细胞到大鼠海马,假手术组给予等量生理盐水,模型组大鼠不做处理。采用Morris水迷宫检测大鼠空间学习记忆能力。损伤后第90天处死大鼠,观察海马组织有无Brdu+神经元特异性烯醇化酶、Brdu+胶质纤维酸性蛋白免疫组织化学双染阳性细胞,并且观察从侧脑室到海马是否存在神经元前体细胞的标志Doublecortin (DCX)吻侧迁移流。 结果与结论：①移植组大鼠采用Morris水迷宫检测大鼠空间学习记忆能力逃避潜伏期及跨越平台次数优于模型组及假手术组(P < 0.05)。②移植组大鼠海马组织及其周围可见免疫组织化学双染阳性细胞,但未见从侧脑室到海马关于神经元前体细胞的标志Doublecortin (DCX)吻侧迁移流。结果提示,骨髓间充质干细胞移植可以促进脑损伤大鼠的神经功能的恢复,其机制可能与移植细胞分化为神经元样和神经胶质细胞样细胞,并分泌或促进宿主分泌神经营养因子有关。     

实验性抑郁症大鼠缰核和海马BDNF基因表达

目的：研究抑郁症大鼠缰核和海马BDNF基因的表达情况。方法：采用长期未预知应激刺激致大鼠抑郁症模型，运用open-field和forced swinmming test法观察大鼠行为学变化。运用免疫组化法检测缰核和海马BDNT基因的表达。结果：与正常对照组相比，抑郁症模型组大鼠海马和缰核均表现为BDNF阳性细胞数量明显减少。结论：实验性抑郁症大鼠缰核、海马BDNF基因表达水平降低。     

丙烯酰胺染毒对乳鼠海马齿状回神经元SYP和DCX表达的影响

目的探究丙烯酰胺(acrylamide,ACR)孕哺期染毒对乳鼠海马齿状回神经元突触囊泡膜蛋白(SYP)和微管相关蛋白(DCX)表达的影响。方法 32只SPF级SD雌鼠随机分为对照组(0 ppm)和低(50 ppm)、中(100 ppm)、高(200 ppm)剂量染毒组。在雌鼠妊娠第6天至分娩后第21天,通过饮水建立ACR母源性染毒模型。乳鼠出生后第21天取材,免疫荧光组织化学检测海马神经元SYP和DCX的表达情况。结果免疫荧光组织化学检测结果显示,与对照组和低剂量组相比较,中、高剂量组海马齿状回中SYP和DCX阳性细胞的平均光密度均显著减小(P0.05)。结论 ACR染毒可能是通过降低海马齿状回神经元SYP和DCX的表达,干扰海马神经元突触的形成及神经元的增殖和分化,抑制神经元的发育。     

模拟失重后大鼠海马齿状回神经发生的实验研究

观察模拟失重对大鼠海马齿状回神经发生的影响,为进一步阐明模拟失重对成年大鼠海马齿状回神经发生影响的规律及其相关生物学机制提供基本的实验依据。采用尾部悬吊法建立大鼠模拟失重模型,通过5-溴-2’-脱氧尿苷(5-bromo-2’-de-oxyuridine,BrdU)标记分裂细胞、微管相关蛋白(doublecortin,DCX)标记神经干细胞、神经元核蛋白(NeuN)标记神经元及胶质原纤维酸性蛋白(GFAP)标记神经胶质细胞的单、双重免疫组织化学染色方法比较尾部悬吊后7、14、28d模拟失重组大鼠与相应时间对照组大鼠之间海马齿状回神经前体细胞增殖、迁移和分化的情况。结果显示:模拟失重后7、14d尾部悬吊法模拟失重大鼠齿状回的BrdU免疫阳性细胞数目较相应对照组明显减少(P<0.01),而模拟失重后28d时两组大鼠齿状回BrdU免疫阳性细胞数目无显著差异(P>0.05)。本研究结果提示,模拟失重可抑制海马齿状回神经发生的水平。     

大鼠海马过表达脑源性神经营养因子对脑卒中后抑郁行为的影响

目的:本研究旨在阐明脑源性神经营养因子(BDNF)过表达对脑卒中后抑郁症(PSD)大鼠抑郁样行为的影响。方法;构建BDNF过表达慢病毒载体,先结扎阻断大脑中动脉建立大鼠局灶性脑缺血模型,再采用孤养结合慢性不可预见性温和应激(CMUS)建立PSD大鼠模型。然后海马注射BDNF过表达慢病毒(PSD+LV-BDNF组),应用Real-time PCR和免疫印迹检测海马BDNF mRNA和蛋白的表达水平。结果:BDNF过表达慢病毒注射后第28天,PSD+LV-BDNF组的BDNF mRNA、蛋白表达均多于PSD组。分别于CMUS后、手术前和注射后28 d采用糖水消耗试验和旷场试验检测大鼠抑郁样行为,PSD+LV-BDNF组的糖水消耗量及水平移动次数比PSD组均显著增加。结论:在PSD大鼠海马内BDNF、的过表达可改善对脑卒中后抑郁症的抑郁样行为,发挥神经保护作用。     

正常成年大鼠神经元前体细胞的迁移

目的探讨正常成年大鼠脑中神经元前体细胞的迁移路径和迁移特征,为病理状况下的神经元迁移研究提供理论和实验基础。方法将成年大鼠脑组织按冠状位和矢状位行冰冻切片（片厚20μm）,采用免疫组织化学染色技术观察Doublecortin（DCX）免疫阳性细胞的迁移路径以及DCX阳性细胞的迁移特征。结果正常成年大鼠神经元前体细胞的迁移主要有两条路径：一条是从室下区到嗅球的吻侧迁移流,另一条是位于皮层和胼胝体之间的胼胝体周围迁移流。吻侧迁移流中的DCX免疫阳性细胞较规则的有序排列,形态上呈梭形的胞体和单个较长的前导突起,前导突起基本朝向嗅球,细胞大小基本一致：而胼胝体周围迁移流中的DCX免疫阳性细胞胞体呈类圆形,突起的大小、数目和方向多样。结论研究神经元前体细胞的迁移不仅有助于明确其迁移的具体机制,而且有助于控制神经元的迁移和设计有效的治疗策略。     

脑源性神经营养因子体外诱导神经干细胞向神经元分化

目的观察脑源性神经营养因子(BDNF)对新生SD大鼠海马神经干细胞在体外分化为神经元的作用。方法取新生SD大鼠海马组织,以无血清培养技术培养获得神经干细胞,在BDNF诱导下让其在体外分化,7d后,通过免疫荧光技术结合图像分析技术来观察分化所得神经丝(neurofilament,NF)抗原阳性神经元的比率及其最长突起的长度。结果BDNF组分化所得细胞NF阳性率为13.66%,神经元突起长度为(146.27±26.30)μm,对照组分化所得细胞NF阳性率为9.38%,神经元突起长度为(117.00±23.98)μm,两组结果有显著性差异。结论BDNF能提高新生SD大鼠海马神经干细胞体外定向分化为神经元的比率,并且能刺激新生神经元突起的生长。     

Effect of aging on the expression of BDNF and TrkB isoforms in rat pituitary

Brain-derived neurotrophic factor (BDNF) is a key regulator of neuronal plasticity in adult rat brain and its effects are mediated through TrkB receptors. BDNF and its receptors are also localized in the pituitary, but their expressions throughout the rat lifespan are poorly known. Here we analyzed levels of BDNF and the different subtypes of TrkB receptors (mRNA and proteins) in the rat pituitary at different stages of life. BDNF immunoreactivity was expressed in folliculo-stellate cells from the anterior pituitary and in the intermediate lobe. TrkB.FL and TrkB.T1 receptors were strongly and essentially expressed in the intermediate lobe similar to the alpha-MSH localization pattern. These receptors begun decreasing at middle-age but TrkB.T2 was not detected in the pituitary at any age. Finally, in vitro alpha-MSH release from the intermediate lobe was correlated with the receptor content throughout the lifespan. The present results demonstrate the presence of BDNF in folliculo-stellate cells and indicated that receptors, rather than BDNF itself, are impaired with aging. These changes can contribute to explain age-dependent endocrine changes.     

Oroxylin A increases BDNF production by activation of MAPK-CREB pathway in rat primary cortical neuronal culture

Oroxylin A (5,7-dihydroxy-6-methoxyfavone) is a flavonoid compound originated from the root of Scutellaria baicalensis Georgi. Our previous reports suggested that oroxylin A improves memory function in rat, at least in part, by its antagonistic effects on GABA(A) receptor. In addition, oroxylin A protects neurons from ischemic damage by mechanisms currently not clear. In this study we determined whether oroxylin A modulates the level of brain derived neurotrophic factor (BDNF) in primary rat cortical neuronal culture, which is well known for its role on neuronal survival, neurogenesis, differentiation of neurons and synapses and learning and memory. Treatment of oroxylin A for 3-48h increased BDNF expression which was analyzed by ELISA assay and Western blot analysis. Oroxylin A induced slow but sustained increases in intracellular calcium level and activated ERK1/2 mitogen activated protein kinase (MAPK). In addition, oroxylin A phosphorylated cyclic AMP response element binding protein (CREB) at Ser 133 in concentration and time dependent manner. Pretreatment with the MAPK inhibitor PD98059 (10μM) attenuated phosphorylation of ERK1/2 and CREB as well as BDNF production, which suggests that oroxylin A regulates BDNF production by activating MAPK-CREB pathway. GABA(A) antagonist bicuculline mimicked the effects of oroxylin A on BDNF production as well as MAPK-CREB pathway. Increase in intracellular Ca(2+) concentration, phosphorylation of ERK1/2 and CREB, and BDNF expression by oroxylin A was blocked by NMDA receptor inhibitor MK-801 (10μM) as well as tetrodotoxin (TTX, 0.5 and 1μM). The results from the present study suggest that the calcium and p-CREB dependent induction of BDNF expression, possibly via activation of synaptic NMDA receptor through the blockade of GABA(A) activity in cortical neuronal circuitry, might be responsible for the neuroprotective or memory enhancing effects of oroxylin A.     

嗅茎切断对脑室下层细胞迁移的影响

为探讨嗅茎切断对大鼠前脑侧脑室脑室下层细胞迁移的影响 ,本实验在嗅球后切断嗅茎 ,手术后 30 d、6 0 d后灌注固定处死 ,制作脑的连续石蜡切片 ,计量嗅球后份平面吻侧迁移流的细胞密度 ,计算机图象分析吻侧迁移流横截面积 ,用免疫组织化学技术对吻侧迁移流内的细胞进行定性分析。结果发现 ,手术切断嗅茎导致手术侧吻侧迁移流细胞在切断平面的尾侧细胞密度增加 ,吻侧迁移流的横截面积增大 ,积聚的细胞为多唾液酸 -神经细胞粘附分子阳性的神经元前体细胞。结果提示 ,手术切断嗅茎导致吻侧迁移流内神经元前体细胞在切断平面的尾侧积聚     

Increased central brain-derived neurotrophic factor activity could be a risk factor for substance abuse: Implications for treatment

Drug addiction is a common psychiatric disorder with complex genetic, psychological and social contributing factors. While the midbrain dopaminergic system is crucial for acute reward and the initiation of addiction, evidence suggests that there are permanent neuronal changes at the cellular and molecular levels that underlie the addictive process. Brain-derived neurotrophic factor (BDNF), a member of the neurotrophic factor family and the most abundant neurotrophins in the brain, plays a key role in the survival and differentiation of midbrain dopaminergic (DA) neurons. Evidence from animal and clinical studies suggests that increased central BDNF activity may be implicated in the pathogenesis of drug addiction. For example, BDNF infusion into rat midbrain enhances the rewarding effects of cocaine as measured by the condition place preference paradigm. In contrast, cocaine-conditioned place preference was reduced in heterozygous BDNF knockout mice. In humans, the 66Val allele of the BDNF-gene Val66Met polymorphism is associated with higher BDNF secretion in response to neuronal stimulation compared with the 66Met allele. We found higher BDNF 66Val homozygote frequency in people with drug addiction compared with normal controls. Furthermore, plasma BDNF concentrations of methamphetamine users were significantly higher than controls. The increased central BDNF activity hypothesis of drug addiction may provide new insights for improved therapeutic strategies for the prevention and treatment of drug addiction. Several strategies to decrease central BDNF activity that have potential use in the treatment of drug addiction are proposed.     

Hippocampal neurokinin-1 receptor and brain-derived neurotrophic factor gene expression is decreased in rat models of pain and stress

Acute or chronic stress can alter hippocampal structure, cause neuronal damage, and decrease hippocampal levels of the neurotrophin brain-derived neurotrophic factor (BDNF). The tachykinin substance P and its neurokinin-1 (NK-1) receptor may play a critical role in neuronal systems that process nociceptive stimuli; their importance in stress-activated systems has recently been demonstrated by the antidepressant-like actions of NK-1 receptor antagonists. However, the functional similarities between neurokinin receptors in the hippocampus and those in sensory systems are poorly understood, as is the significance of hippocampal NK-1 receptor in the context of chronic pain. Therefore, we investigated the effects of immobilization stress or inflammatory stimuli on NK-1 receptor and BDNF gene expression in the rat hippocampus. Rats received an acute or chronic immobilization stress, or an acute (formalin) or chronic (complete Freund's adjuvant) inflammatory stimulus to the right hind paw. Subsequently hippocampal volume and specific gravity were measured and NK-1 receptor and BDNF mRNA levels quantified using ribonuclease protection assays. Results showed that either stress or pain down-regulates expression of both NK-1 receptor and BDNF genes in the hippocampus. Hippocampal volume was increased by either pain or stress; this may be due to edema (decreased specific gravity). Thus, BDNF and NK-1 receptor gene plasticity may reflect sensory activation or responses to neuronal injury. These data may provide useful markers of hippocampal activation during chronic pain, and suggest similarities in the mechanisms underlying chronic pain and depression.     

Stimulatory effects of a melatonin receptor agonist, ramelteon, on BDNF in mouse cerebellar granule cells

Melatonin receptor activation has been linked to the regulation of neurotrophic factors, including the brain-derived neurotrophic factor (BDNF). To further characterize the effects of melatonin receptor stimulation on neuronal BDNF, we used a clinically available novel agonist for MT1 and MT2 melatonin receptors, ramelteon. Primary cultures of cerebellar granule cells (CGC) have been established as an in vitro model for studying neuronal BDNF. We took advantage of the availability of MT1- and MT2-deficient (knockout; KO) mice to employ primary CGC prepared from wild type (WT), MT1 KO, and MT2 KO mice. We investigated the effects of ramelteon on BDNF protein and mRNA content. Administered in a low nanomolar range, ramelteon increased BDNF protein content in all three types of mouse CGC. This ramelteon-triggered BDNF protein elevation was not preceded by a BDNF mRNA increase. However, it was prevented by treatment of cultures with a protein synthesis inhibitor cycloheximide. These results demonstrated that the MT1/MT2 melatonin receptor agonist ramelteon is capable of increasing BDNF protein in neurons expressing either of the two melatonin receptor types and that this action of ramelteon involves translational mechanisms. Further research is needed to explore the putative influence of ramelteon on BDNF-associated neuroplasticity.     

Confocal visualization of the effect of short-term locomotor exercise on BDNF and TrkB distribution in the lumbar spinal cord of the rat: the enhancement of BDNF in dendrites?

Locomotor exercise increases neurotrophin BDNF and its receptor TrkBFL expression in the lumbar spinal cord. Involvement of BDNF/TrkBFL in synaptic transmission raises the questions which intracellular compartments are involved in this upregulation and whether exercise leads to redistribution of these proteins related to the duration of exercise. We have investigated the influence of short-term (7 days) locomotor exercise (ST) on intracellular distribution of BDNF and TrkBFL in the rat lumbar spinal cord comparing it with the effects of long-term (28 days) exercise (LT) described earlier. Immunofluorescence (IF) of proteins was analyzed with confocal microscopy. ST exercise caused a redistribution of perikaryonal BDNF IF toward periphery resulting in an increase of dendritic signal. In contrast to an enhancement of perikaryonal BDNF staining following LT, no increase of BDNF IF in cell bodies was observed after ST. An increase of TrkBFL IF in oligodendrocytes was consistent with that caused by LT. The fibers of TrkBFL IF oligodendrocytes surrounding the largest neurons were in close apposition to neuronal membrane. We propose that ST exercise causes (1) BDNF translocation to dendrites and/or local dendritic synthesis to serve increased synaptic activity (2) sensitization of oligodendroglia to BDNF mediated responses.     

A saturated-fat diet aggravates the outcome of traumatic brain injury on hippocampal plasticity and cognitive function by reducing brain-derived neurotrophic factor

We have conducted studies to determine the potential of dietary factors to affect the capacity of the brain to compensate for insult. Rats were fed with a high-fat sucrose (HFS) diet, a popularly consumed diet in industrialized western societies, for 4 weeks before a mild fluid percussion injury (FPI) or sham surgery was performed. FPI impaired spatial learning capacity in the Morris water maze, and these effects were aggravated by previous exposure of the rats to the action of the HFS diet. Learning performance decreased according to levels of brain-derived neurotrophic factor (BDNF) in individual rats, such that rats with the worst learning efficacy showed the lowest levels of BDNF in the hippocampus. BDNF immunohistochemistry localized the decreases in BDNF to the CA3 and dentate gyrus of the hippocampal formation. BDNF has a strong effect on synaptic plasticity via the action of synapsin I and cAMP-response element-binding protein (CREB), therefore, we assessed changes in synapsin I and CREB in conjunction with BDNF. Levels of synapsin I and CREB decreased in relation to decreases in BDNF levels. The combination of FPI and the HFS diet had more dramatic effects on the active state (phosphorylated) of synapsin I and CREB. There were no signs of neurodegeneration in the hippocampus of any rat group assessed with Fluoro-Jade B staining. The results suggest that FPI and diet impose a risk factor to the molecular machinery in charge of maintaining neuronal function under homeostatic and challenging situations.