Effect of acute and chronic stress on the expressiion of BDNF and BDNF mRNA in the hippocampus of rats

目的 观察急性应激和重复低强度强迫游泳应激后大鼠海马BDNF mRNA及蛋白在不同时间点的动态表达;观察慢性应激条件下动物行为改变.方法 用反转录-聚合酶链反应(RT-PCR)法和Western blot检测海马BDNFmRNA及蛋白表达.结果 急性应激导致海马BDNF mRNA及其产物表达增加,3 h表达高峰(7.4147 ±0.6821,P＜0.01);慢性应激后BDNF蛋白表达降低,并在180和720 min两个时间点显著低于急性应激组(3.6581 ±0.2561;3.6051 ±0.4453,P＜0.05).结论 不同强度及时程应激对BDNF mRNA及蛋白表达有差异;慢性应激组大鼠BNDF mRNA表达存在一定适应现象.     

慢性应激对心肌梗死后大鼠模型行为学及海马BDNF的影响

目的:探讨慢性应激对心肌梗死后大鼠模型行为学及海马BDNF的影响.方法:建立急性心肌梗死模型.结合慢性不可预见的轻度应激和孤养制作心梗并抑郁复合大鼠模型.观察动物的体重变化和行为学指标,用Westernblot方法检测海马BDNF蛋白表达.结果:经过21天慢性不可预见轻度应激.模型组大鼠体重、糖水消耗和糖水偏爱百分比、敞箱试验得分均明显降低,纯水消耗显著增加;海马BDNF蛋白表达减少(P<0.05).结论:对急性心肌梗死大鼠采用21天慢性应激后,模型鼠体重下降、行为学明显异常,符合抑郁动物的行为学改变,且存在海马神经元可塑性降低的表现,这可能是心肌梗死并抑郁发病的机制之一.     

三种复方对慢性应激模型大鼠海马CREB、BDNF基因表达的影响

 目的:探讨慢性应激肝郁模型大鼠海马CREB、BDNF基因表达及疏肝、疏肝健脾与健脾3种方剂的效应。方法:SD雄性大鼠40只,用随机区组设计的方法分为对照组、模型组、四逆散组、逍遥散组和四君子汤组,多种应激处理共21 d后,测定1%蔗糖水摄取率和强迫游泳中累计不动时间,用RT-PCR的方法检测海马CREB和BDNF mRNA表达。结果:与对照组比较,模型组大鼠1%蔗糖水摄取率明显降低,强迫游泳中累计不动时间明显延长,海马CREB、BDNF mRNA表达明显降低;与模型组比较,四逆散组、逍遥散组的1%蔗糖水摄取率明显升高,强迫游泳中累计不动时间明显缩短,CREB、BDNF mRNA表达均明显升高;四君子汤组各行为学指标及BDNF表达与模型组相比没有差异,仅CREB表达升高。结论:慢性应激肝郁模型大鼠海马CREB、BDNF的mRNA表达降低,具有疏肝作用的方剂四逆散和逍遥散可以对抗这种降低,而健脾方剂四君子汤无明显效应。     

大豆甙元对慢性应激大鼠海马BDNF和NPY表达及非特异免疫调节的作用

目的:探讨大豆甙元(Daidzein)对慢性应激抑郁模型大鼠海马脑源性神经生长因子(BDNF)、神经肽Y(NPY)蛋白表达和非特异免疫调节作用的影响。方法:取健康成年SD大鼠40只,雄性,体质量(210±19)g,清洁级,用1%蔗糖水喂养4 d,使动物原来的饮水习惯发生改变。第5天开始24 h禁水,但不禁食,第6天给予1%蔗糖水4 h,测1%蔗糖水的偏嗜度。根据1%蔗糖水偏嗜度和体重随机分成4组,每组10只,糖水偏嗜度和体重各组间没有显著差异(P0.05)。正常对照组(CG)、模型对照组(MG)、氟西汀对照组(FG,10.0 mg/kg)、大豆甙元组(DG,80.0 mg/kg)。造模同时灌胃给药,每日1次,连续给药32 d。造模方法为慢性轻度不可预见性的应激模型加孤养。观察大鼠的行为改变,免疫蛋白印记(Western blot)技术和免疫组织化学法检测海马BNDF和NPY表达,观察淋巴细胞增值功能,脾脏指数,外周血白细胞数目及抗体分泌细胞功能。结果:与正常对照组相比慢性应急刺激大鼠体重、蔗糖消耗量及大鼠旷场试验得分显著降低,游泳不动时间延长,海马BNDF和NPY表达水平低下,差异有统计学意义(P0.01)。氟西汀治疗组和大豆甙元治疗组与模型对照组相比大鼠体重、蔗糖消耗量、大鼠旷场试验得分以及海马BNDF和NPY表达水平显著增加,差异有统计学意义(P0.05或P0.01)。大豆甙元组大鼠外周血白细胞数目、抗体分泌细胞功能及淋巴细胞增殖力显著高于模型组。大豆甙元剂量脾脏指数显著高于模型组(P0.01)。结论:大豆甙元能显著拮抗慢性应激模型大鼠抑郁症状,大豆甙元可增加海马内BDNF和NPY蛋白的含量,并且有增强慢性应激模型大鼠体液免疫应答和淋巴细胞增殖能力的作用,大豆甙元拮抗慢性应激模型大鼠抑郁作用的机制可能与大豆甙元治疗后海马中BDNF和NPY蛋白含量增加及免疫调节作用有关。     

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。     

仙茅苷对老年痴呆模型大鼠学习记忆能力及海马BDNF/TrkB表达的影响

目的探讨仙茅苷对老年痴呆模型大鼠学习记忆能力及海马脑源性神经营养因子/酪氨酸激酶受体B(BDNF/TrkB)表达的影响。方法 36只健康成年SD大鼠,随机分为对照组、模型组与仙茅苷组,每组l2只。采用皮下注射D-半乳糖联合双侧海马注射Aβ25-35构建痴呆模型大鼠,仙茅苷灌胃8周后,Morris水迷宫方法观察各组大鼠的学习记忆能力,免疫组织化学方法和Western Blot方法检测各组大鼠海马BDNF与TrkB的表达,real time PCR方法检测各组大鼠海马BDNF mRNA与TrkB mRNA的表达。结果与对照组相比,模型组大鼠的平均潜伏期明显延长,探索次数明显减少;与模型组相比,仙茅苷组大鼠的平均潜伏期明显缩短,探索次数明显增加。模型组大鼠海马BDNF与TrkB mRNA与蛋白表达水平显著低于对照组;而仙茅苷组大鼠在给予治疗后显著高于模型组。结论仙茅苷能够提高老年痴呆模型大鼠学习记忆能力,可能与激活BDNF/TrkB信号通路相关。     

侧脑室注射PP2对慢性复合应激大鼠学习记忆功能和海马内Fyn、BDNF和TrkB表达的影响

为了探讨酪氨酸激酶抑制剂PP2对慢性复合应激性学习记忆增强大鼠的学习记忆功能和海马内非受体酪氨酸激酶(Fyn)、脑源性神经营养因子(BDNF)和Trk酪氨酸激酶B(TrkB)表达的影响,本实验将成年雄性大鼠22只,随机分为三组:即慢性复合应激组(对照组)、慢性复合应激+注射盐水组(盐水组)和慢性复合应激+注射PP2组(PP2组)。全部动物暴露于复合应激原中6周后,盐水组和PP2组动物分别侧脑室注射生理盐水或PP2(1次/d,共11d)。实验结束后,用Morris水迷宫测试大鼠的空间学习记忆成绩;采用免疫组织化学方法检测Fyn、BDNF和TrkB在海马内蛋白表达的变化。结果显示:与对照组和盐水组相比,PP2组动物的学习与记忆成绩明显下降(P<0.05);海马内Fyn和BDNF蛋白阳性表达减弱(P<0.05);但3组动物海马内TrkB的蛋白表达无显著性差异(P>0.05)。上述结果表明:侧脑室注射PP2可抑制大鼠慢性复合应激性学习记忆能力的增强作用,下调Fyn和BDNF在海马内的表达;提示Fyn和BDNF/TrkB信号转导途径在慢性复合应激增强大鼠学习记忆能力的过程中发挥重要作用。     

慢性应激对不同月龄大鼠前额叶皮质、纹状体脑源性神经营养因子表达的影响

目的:观察慢性应激对不同月龄大鼠行为、前额叶皮质、纹状体脑源性神经营养因子(BDNF)表达的影响.方法:采用慢性轻度不可预知性应激建立动物模型,观察2月龄和15月龄48只Wistar大鼠的行为学、前额叶皮层和纹状体细胞形态学及BDNF的表达.结果:与对照组相比,青年应激大鼠水平运动、直立次数均明显减少,这一变化在老年应激组更明显.应激组糖水偏爱百分比显著低于对照组,并持续到应激结束后一周;老年应激组的糖水偏爱百分比低于青年组.应激组前额叶皮层和纹状体神经细胞呈程度不同的损伤现象,且老年应激组的损伤较青年组严重.应激组前额叶皮质和纹状体BDNF表达明显下调,老年应激组下调明显.应激后一周,青年应激组BDNF表达有一定程度的升高,但仍显著低于对照组.结论:慢性轻度不可预知性应激引起老年大鼠明显的行为学改变,提示老年大鼠对应激的反应性和耐受性降低.应激导致前额叶皮层和纹状体细胞的变性、萎缩和死亡及BDNF表达下降,这一变化在老年组更为明显.     

白藜芦醇对高脂饮食去卵巢肥胖大鼠海马组织脑源性神经营养因子水平的影响

 目的：探讨去卵巢联合高脂饮食诱导的肥胖大鼠海马组织中脑源性神经营养因子（BDNF）、雌激素受体α (ERα)和雌激素受体β (ERβ) 表达的变化,同时观察白藜芦醇对这些改变的影响。方法：50只3月龄雌性Wistar大鼠随机分为5组：假手术普通饮食对照（C）组、假手术高脂饮食（H）组、单纯去卵巢（O）组、去卵巢高脂饮食（O+H）组和白藜芦醇（40 mg·kg-1·d-1）+去卵巢高脂饮食(O+H+R)组。3月后抽取股动脉血检测血清雌二醇（E2）、总胆固醇（TC）、甘油三酯（TG）、高密度脂蛋白胆固醇（HDL-C）和低密度脂蛋白胆固醇(LDL-C)含量;实时荧光定量PCR法检测海马BDNF、ERα和ERβ mRNA表达,蛋白免疫印迹法及ELISA法分别检测海马BDNF蛋白含量。结果：与C组比较,H组大鼠血清TC和LDL-C含量升高,海马BDNF水平显著降低（P<0.05或P<0.01）,O组大鼠血清E2水平降低,TC含量升高,海马BDNF 水平及ERα、ERβ mRNA表达均明显下降（P<0.05或P<0.01）;O+H组大鼠血清TC含量升高,HDL-C水平降低,海马BDNF 水平降低,与C组、H组和O组比较均有显著差异（P<0.05或P<0.01）,海马ERα和ERβ mRNA表达下降,与C组和H组比较差异显著（P<0.05或P<0.01）;O+H+R组大鼠血清E2水平升高,TC含量降低,海马ERα和ERβ mRNA表达水平及BDNF含量均明显增加,与O+H组比较有显著差异（P<0.05或P<0.01）。结论：去卵巢联合高脂饮食显著降低大鼠海马ERα和ERβ mRNA表达及BDNF水平,而白藜芦醇能够明显改善绝经后肥胖大鼠的血脂水平,上调海马ERα和ERβ mRNA表达,增加海马BDNF水平。     

慢性应激对大鼠海马Bcl-xl表达的影响及应激后的变化

目的:探讨慢性应激对大鼠海马神经元Bcl-xl蛋白表达的影响及其应激后的变化。方法:采用慢性强迫冰水游泳制作动物模型。运用open-field法观察大鼠行为学的变化,运用免疫组织化学方法观察大鼠海马DG区、CA3区Bcl-xl的变化。结果:与对照组相比,实验组1大鼠海马CA3区齿状回(DG)区Bcl-xl平均灰度值显著增加(t=4.69,P<0.05和t=3.77,P<0.01),实验组2平均灰度值与对照组2相比同样增加(t=3.35,P<0.05和t=3.30,P<0.05)。结论:慢性应激使大鼠海马Bcl-xl表达降低,应激三十天后,其表达仍低于对照组。     

BDNF对慢性应激性大鼠海马神经元损伤的保护作用

目的研究脑源性神经营养因子(BDNF)对大鼠海马神经元的保护作用。方法40只成年Wistar大鼠随机分为对照组、应激组、BDNF低剂量组和高剂量组,每组10只。用电击足底结合噪声建立慢性应激大鼠模型,Morris水迷宫观察动物的空间学习和记忆能力,Nissl染色观察和计数海马神经元数量,Fara-2荧光法测海马突触体内游离钙浓度。结果在双海马注射BDNF后,对于因慢性应激引起的空间学习和记忆能力下降,海马神经元数量减少,海马突触体内游离钙浓度增高有明显保护作用。结论BDNF对应激海马损伤有保护作用,其机制可能是通过调节海马细胞内的钙浓度,防止海马神经细胞丢失有关。     

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。     

Modulation of BDNF and TrkB expression in rat hippocampus in response to acute neurotoxicity by diethyldithiocarbamate

In this study, we examined the expression profile of brain-derived neurotrophic factor (BDNF) and its receptor TrkB in adult rat hippocampus following acute administration of diethyldithiocarbamate (DDTC), a neurotoxic compound which was previously shown to induce microglia activation and cell death. Semiquantitative RT-PCR analysis detected significant variations of BDNF mRNA levels in whole hippocampus homogenates, with a peak at 24h after DDTC injection. Increased BDNF protein expression was demonstrated by immunohistochemistry in various hippocampal subfields. The most relevant increase was observed in the hilus of the dentate gyrus where BDNF levels at 120h were found to be almost four times those of basal levels. Full-length TrkB (TrkB.FL) encoding mRNA was also shown to undergo an earlier increase in the hippocampus of DDTC-treated rats. TrkB immunostaining with an antibody binding both full-length and truncated (TrkB.T) isoforms was found to increase at 120h in the hippocampal CA2 and CA3 regions. These results demonstrate that DDTC modulates the expression of BDNF and its receptor in the adult rat hippocampus and suggest a possible involvement of this neurotrophin in the protective response to DDTC-induced neuronal damage.     

Expression and Role of the BDNF Receptor-TrkB in Rat Adrenal Gland under Acute Immobilization Stress

We reported that plasma brain-derived neurotrophic factor (BDNF) was maximally elevated following a 60-min period of acute immobilization stress and that salivary glands were the main source of plasma BDNF under this stress condition. However, the expression pattern of the BDNF receptor, Tyrosine receptor kinase B (TrkB), under this condition has yet to be determined. We therefore investigated the effect of this stress on the expression level of TrkB in various rat organs using real-time PCR. No significant differences were found between controls and 60 min-stressed rats with respect to TrkB level in various organs. Only adrenal glands showed significantly increased TrkB mRNA levels after 60 min of stress. TrkB mRNA and protein were observed to localize in chromaffin cells. In addition, we investigated whether BDNF-TrkB interaction influences the release of stress hormones from PC12 cells, derived from chromaffin cells. Truncated receptor, TrkB-T1, was identified in PC12 cells using RT-PCR. Exposure of PC12 cells to BDNF induced the release of catecholamine. This BDNF-evoked release was totally blocked by administration of the K252a in which an inhibitor of Trk receptors. Thus, BDNF-TrkB interactions may modulate catecholamine release from adrenal chromaffin cells under acute stress conditions.     

Chronic stress, as well as acute stress, reduces BDNF mRNA expression in the rat hippocampus but less robustly

Daily restraint for 3 weeks was shown to atrophy dendrites of hippocampal pyramidal neurons in rats. Brain-derived neurotrophic factor (BDNF), which maintains neuronal survival and morphology, has been shown to decrease in response to acute stress. Plasma glucocorticoid (GC) and serotonergic projections from the raphe nuclei play major roles in reducing BDNF synthesis in the hippocampus. We investigated BDNF mRNA levels there, together with plasma GC levels, GC receptors in the hippocampus/hypothalamus and 5-HT synthesizing enzyme, tryptophan hydroxylase in the raphe nuclei, in animals chronically stressed for 1-3 weeks, using in situ hybridization and immunohistochemistry. In these animals, BDNF mRNA levels were significantly decreased in the hippocampus after 6 h of restraint, but the ability of restraint to reduce BDNF synthesis seemed less robust than that seen in acute stress models. HPA axis response to stress in these animals assessed by plasma GC levels was delayed and sustained, and the GC receptor in the paraventricular hypothalamic nucleus was increased at 1 week. Tryptophan hydroxylase immunoreactivity was increased in the median raphe nucleus at 2-3 weeks. Repetitive stress-induced reduction of BDNF may partly contribute to the neuronal atrophy/death and reduction of hippocampal volume observed both in animals and humans suffering chronic stress and/or depression.     

右美托咪定对抑郁症大鼠行为及海马BDNF和mTOR蛋白表达的影响

目的:观察右美托咪定(DEX)对抑郁症大鼠行为及海马脑源性神经营养因子(BDNF)和哺乳动物雷帕霉素靶蛋白(mTOR)表达的影响并探讨其机制。方法:实验设5组,即假手术(sham)组、抑郁症模型(model)组及DEX(2.5、5和10μg/kg)组,每组12只大鼠。抑郁症动物模型采用卵巢摘除加慢性不可预知性温和应激法制备。DEX各剂量组大鼠连续腹腔注射给药21 d。强迫游泳及旷场实验观察大鼠行为变化。Morris水迷宫实验评价大鼠空间学习和记忆能力。海马神经元病理变化采用尼氏染色法检测。大鼠海马白细胞介素1β(IL-1β)、IL-6和肿瘤坏死因子α(TNF-α)mRNA的表达水平采用RT-qPCR法检测。Western blot检测海马IL-1β、IL-6、TNF-α和BDNF蛋白表达水平及蛋白激酶A(PKA)、cAMP反应元件结合蛋白(CREB)、原肌球蛋白相关激酶B(TrkB)、磷脂酰肌醇3-激酶(PI3K)、蛋白激酶B(Akt)和mTOR蛋白的磷酸化水平。结果:与model组相比,DEX各剂量组大鼠强迫游泳不动时间明显降低,自发活动明显增加,逃避潜伏期明显降低,穿越平台次数明显增加(P<0.05或P<0.01),海马神经元损伤显著减轻,IL-1β、IL-6和TNF-α的表达水平明显降低,PKA、CREB及TrkB的磷酸化水平和BDNF表达水平均明显升高,同时PI3K/Akt/mTOR信号通路蛋白磷酸化水平明显上调(P<0.01)。结论:右美托咪定可改善抑郁症大鼠行为及空间学习和记忆能力,其机制可能与其抗炎、调节海马BDNF蛋白表达及TrkB磷酸化水平、进而激活PI3K/Akt/mTOR信号通路有关。     

Effects of sleep deprivation on behaviors and abnormal hippocampal BDNF/miR-10B expression in rats with chronic stress depression

Being sleep-deprived can relieve the depressed emotions in rats, but the underlying mechanisms remain unknown. In this study, male rats were divided into 3 groups: normal control (NC), chronicunpredictable stress (CUPS) and sleep-deprived (SD). All of the groups were examined using the sucrose consumption test and the open field test. The sucrose consumption test and the open field test were performed for all three groups. The BDNF and miR-10B expressions were examined using real-time PCR and the level of BNDF was discovered by western blotting. In the sucrose consumption test and the open field test, the CUPS rats consumed less sucrose and got fewer score than the NC rats, however the SD rats consumed significantly more sucrose and received higher scores than the CUPS rats. Both the expression of BNDF and the protein levels in the CUPS group was significantly lower than in the NC group. Also, the CUPS group also showed a higher miR-10B expression than the NC group. However, the SD group demonstrated higher BDNF expression and lower miR-10B expression when compared with the CUPS group. Further investigation demonstrated that the BDNF is the direct target gene of miR-10B and BDNF expression, which is negatively correlated with the expression of miR-10B. In the sucrose consumption test, BNDF expression is positively correlated with the sucrose preference rate whereas miR-10B has an opposing correlation. Moreover, the open field test demonstrated that BNDF expression is positively correlated with the scores and the miR-10B expression is negatively correlated. These results indicate that sleep deprivation is closely linked with the downregulation of miR-10B and possibly the upregulation of BDNF in the hippocampus in the CUPS rats.