慢性复合应激性增强空间学习与记忆时突触素Ⅰ在大鼠海马中的表达

目的观察突触素Ⅰ在慢性复合应激性空间学习与记忆增强大鼠海马各亚区表达的变化及其意义.方法成年雄性Wistar大鼠随机分成应激组和对照组.采用垂直旋转、剥夺睡眠、噪音刺激和夜间光照4种应激原无规律交替应激动物6周,每天6 h,制作慢性复合应激动物模型.采用Morris水迷宫和Y-迷宫测试大鼠空间学习与记忆成绩,并用免疫组织化学技术显示突触素Ⅰ在慢性复合应激性空间学习与记忆增强大鼠海马中的表达变化.结果结果显示,应激组动物慢性复合应激后在Morris水迷宫内寻找隐蔽平台所需时间(潜伏期)比对照组的明显地短(P<0.05),在Y-迷宫内寻找安全区的正确率比对照组的明显地高(P<0.05);应激组动物慢性复合应激后,其海马齿状回(dentate gyrus,DG)和CA3区突触素I的免疫反应性明显地强于对照组(P<0.05), 两组CA1区突触素I的免疫反应性无明显差别(P>0.05).结论这些结果提示,慢性复合应激可增强大鼠空间学习与记忆能力,突触素Ⅰ在大鼠海马内表达的变化可能参与了大鼠空间学习与记忆增强的机制.     

氟西汀抑制PTSD大鼠海马神经元PSD-95和突触素Ⅰ水平的下调与学习记忆力的损害

目的探讨氟西汀(fluoxetine,FLXT)对创伤后应激障碍(post-traumatic-stress-disorder,PTSD)大鼠记忆及大鼠海马神经元突触后致密物蛋白95(postsynaptic density 95,PSD-95)和突触素Ⅰ(synapsinⅠ)表达的影响。方法采用国际认定的SPS方法刺激大鼠建立PTSD大鼠模型,应用水迷宫实验观察氟西汀对PTSD大鼠学习记忆的影响,采用免疫荧光染色和免疫印迹法检测海马神经元PSD-95和突触素Ⅰ水平。结果 Morris水迷宫前5天的定位航行实验结果显示,SPS刺激后大鼠(PTSD大鼠)找到水下平台的游泳距离和潜伏期比正常组大鼠长,给予氟西汀的PTSD大鼠找到水下平台的距离和潜伏期较未用氟西汀处理的PTSD大鼠缩短。Morris水迷宫第6天空间探索实验结果显示,PTSD大鼠穿越平台的次数和在靶象限花费时间的百分比明显低于正常对照大鼠,而氟西汀可显著增加PTSD大鼠在水迷宫实验中的穿台次数和在靶象限停留的时间百分比。免疫荧光染色和Western Blot检测显示,PTSD大鼠PSD-95和突触素Ⅰ的水平降低,氟西汀干预可抑制PTSD大鼠PSD-95和突触素Ⅰ水平的降低。结论氟西汀可通过抑制PTSD大鼠海马神经元细胞PSD-95和SynapsinⅠ水平的下调,减轻PTSD大鼠空间记忆和学习能力的损伤。     

锁阳乙酸乙酯提取物改善慢性应激小鼠认知功能障碍的神经保护机制

本实验以去卵巢后慢性应激模型,探究锁阳乙酸乙酯提取物(ECS)改善慢性应激小鼠认知功能障碍的神经保护机制。采用Morris水迷宫检测小鼠空间学习记忆能力,Western Blot检测海马组织突触蛋白中突触囊泡蛋白(synaptophysin,Syn)和突触后致密物(Postsynaptic density protein 95,PSD-95)表达量,通过海马组织形态学改变进一步证明ECS的神经保护作用。Morris水迷宫结果显示雌鼠锁阳乙酸乙酯组穿越平台次数增加(P0.01)。Western Blot结果显示,ECS可增加Syn(P0.05)与PSD-95(P0.05)蛋白表达量。HE染色结果显示ECS可减轻海马神经元损伤,改善海马CA1区锥体细胞形态。结果表明ECS能够增加去势后慢性应激小鼠突触蛋白中Syn与PSD-95的表达量,保护海马神经元,改善慢性应激所致学习记忆障碍。     

青蒿素经PI3K/Akt通路改善突触可塑性减轻糖尿病小鼠认知障碍

目的 本研究旨在阐明青蒿素对II型糖尿病（T2DM）小鼠认知功能障碍的改善作用及其机制。方法 C57BL/6J小鼠单次腹腔注射STZ（100 mg/kg）后联合高脂饲料喂养建立T2DM模型。T2DM小鼠随后腹腔注射青蒿素（40 mg/kg/d）或等体积溶剂。干预4周后，新物体识别、Y迷宫和Morris水迷宫实验检测小鼠的学习和记忆能力。蛋白质印迹法（Western blot）检测海马PI3K、Akt、磷酸化Akt、SYN和PSD-95蛋白的表达。透射电镜观察海马CA1区突触密度和突触超微结构改变。结果 与模型组相比，青蒿素干预组T2DM小鼠的认知功能显著改善，海马中PI3K和磷酸化Akt水平升高，SYN和PSD-95蛋白表达增加，CA1区神经元丢失减少。此外，青蒿素干预组小鼠CA1区的突触密度、PSD-95和突触界面曲率增加，突触间隙宽度减小。结论 青蒿素可能通过激活海马PI3K/Akt途径增强突触可塑性，从而减轻T2DM小鼠认知功能障碍；青蒿素有望成为治疗糖尿病性认知功能障碍的新型药物。     

D-半乳糖合并Meynert基底核损毁对海马长时程增强和突触形态的影响

目的 :研究D 半乳糖合并Meynert基底核损毁Alzheimer病 (AD)大鼠模型海马突触可塑性的变化。方法 :通过0 .96 %D 半乳糖致亚急性损伤及鹅膏蕈氨酸损毁Meynert基底核建立AD动物模型 ,应用行为学测试、电生理学方法和电镜观察 ,研究AD模型大鼠海马突触形态结构和长时程增强现象 (long termpotentiation ,LTP)的变化。结果 :①AD模型大鼠在Morris水迷宫的学习记忆能力明显低于对照组 ;②AD大鼠海马CA1区突触的数密度、面密度明显减少 ;③AD模型大鼠海马齿状回产生的LTP较对照组明显降低。结论 :海马突触结构改变和功能可塑性的降低可能与AD大鼠的学习记忆能力下降有关     

永久性局灶性中动脉阻断脑缺血（pMCAO）模型大鼠脑内突触相关蛋白表达的免疫组织化学观察

目的观察永久性局灶性中动脉阻断脑缺血（pMCAO）模型大鼠脑缺血发作后2 d、7 d脑内突触相关蛋白表达的变化。方法制作大鼠永久性局灶性中动脉阻断脑缺血（pMCAO）模型。缺血动物术后随机分为缺血2 d组、缺血7 d组,另设假手术组。在术后2 d、7 d 2个时间点采用HE染色观察动物神经病理学改变,同时采用免疫组织化学法观察动物的缺血侧脑组织突触素-I（synapsin-I）、突触后致密蛋白95（PSD-95）、α-突触核蛋白（α-synuclein）表达情况。结果与假手术组相比,缺血后,模型动物神经元大量变性坏死,数目减少,排列散乱。缺血后2 d,synapsin-I在CA1区、CA3区、皮层表达显著减少（P〈0.05或P〈0.01）,PSD-95在CA1区、皮层表达显著减少（P〈0.05或P〈0.01）,α-synuclein在CA1区神经元产生显著积聚（P〈0.01）;缺血后7 d,synapsin-I在CA1区、皮层表达仍显著降低（P〈0.01）,PSD-95在CA1区、皮层表达显著减少（P〈0.05或P〈0.01）,α-synuclein在CA1、CA3、皮层表达显著增加（P〈0.05或P〈0.01）。结论 pMCAO模型大鼠在脑缺血发生后,神经突触有关蛋白的表达显著改变,并随缺血后不同时间点表达情况不同,这可能与神经元突触重塑有关。突触相关蛋白的表达与缺血损伤程度密切相关。     

通脉益智方对VD大鼠学习记忆行为和海马CA1区突触结构的影响

目的:观察通脉益智方对血管性痴呆模型大鼠学习记忆行为和海马CA1区突触超微结构的影响.方法:应用高脂血症大鼠,采用脑缺血再灌注的方法建立血管性痴呆动物模型,利用跳台实验和Y型迷宫实验检验大鼠的学习记忆能力,应用透射电镜和光镜观察分析海马CA1区神经细胞和突触形态结构的变化.结果:跳台实验和Y型迷宫实验表明模型大鼠学习记忆能力明显下降,而给予通脉益智方组学习记忆能力改善,与模型组相比有显著性差异(p＜0.05).形态学观察显示模型组大鼠海马CA1区神经细胞排列紊乱,核固缩、退化、变性、坏死、消失.突触结构不完整,突触小泡减少;突触间隙模糊,线粒体肿胀、空泡样变.通脉益智方组的神经细胞、突触的形态与模型组相比有明显改善.结论:通脉益智方通过减轻突触的损伤及对神经细胞的保护作用,从而改善了学习记忆能力.     

突触素、神经肽Y(NPY)在糖尿病模型大鼠脑组织细胞中的表达研究

对突触素(synaptophysin)、神经肽Y(NPY)在链尿佐菌素诱导的糖尿病模型大鼠额叶皮质和海马组织细胞中的表达进行研究,并利用UTHSCSA Image Tools 3.0进行图象分析,同时对其与学习记忆的关系进行探讨.选取成年Sprague-Dawley雄性大鼠20只,体重200-300g,随机分为两组.实验组用链尿佐菌素诱导产生糖尿病模型,并以血糖测定和尿糖水平测定进行筛选,另一组为空白对照组.继续饲养4周后,各组大鼠先进行Y型迷宫测试其学习记忆能力,然后取出脑组织,制做连续冰冻切片,对大脑额叶皮质和海马组织进行突触素、神经肽Y酶标免疫组织化学染色,观察这些蛋白在糖尿病大鼠和正常大鼠脑中表达的差异.结果发现糖尿病大鼠在Y型迷宫测试中,错误次数明显增多,糖尿病大鼠额叶皮质和海马神经元数目较正常对照组明显减少,神经细胞内突触素和神经肽Y的表达均较正常对照组明显下降.我们的研究显示突触素和神经肽Y在糖尿病大鼠大脑额叶皮质和海马组织内表达的减少可能与糖尿病组神经细胞突触数目及突触的可塑性下降、学习和记忆能力障碍有关.这可能是造成糖尿病性痴呆的一个因素.     

应激诱发的海马神经元突触增强参与大鼠的新环境学习

本文旨在研究应激对海马新环境空间学习记忆的损伤作用机制.在大鼠海马CA1区埋植电极,刺激schaffer侧枝记录CA1区树突层的兴奋性突触后场电位(field excitatory postsynaptic potential,fEPSP),探索应激对火鼠新环境空间学习的突触可塑性的影响.同时研究了再次新环境空间学习时...     

蛋白激酶Cγ和蛋白磷酸酯酶Aα在慢性复合应激性学习记忆增强大鼠海马中表达的变化

目的 探讨蛋白激酶Cγ(PKCγ)和蛋白磷酸酯酶Aα(PP2B-Aα)在慢性复合应激性学习记忆增强大鼠海马中的表达及其意义。方法 将成年雄性Wistar大鼠随机分为应激组和对照组,对应激组实行慢性复合应激42d后,用Morris水迷宫,Y-迷宫对2组大鼠进行学习和记忆能力测试,然后用免疫组织化学方法,观察2组大鼠PKCγ和PP2B-Aα的表达,并用计算机图像分析系统对免疫阳性反应结果进行处理。结果 应激组比对照组学习记忆能力明显增强;在海马CA3区PKCγ的免疫反应阳性日月显增强;PP2B-Aα在海马CA1和CA3区的免疫反应阳性明显减弱。结论 海马内PKCγ和PP2B-Aα表达的变化可能参与了慢性复合应激致大鼠学习记忆增强的机制。     

慢性复合应激对大鼠学习和记忆及海马神经元神经颗粒素表达的影响

目的探讨慢性复合应激对大鼠学习和记忆功能及海马内神经元神经颗粒素(neurogranin,Ng)表达的影响。方法成年雄性Wistar大鼠随机分为对照组和复合应激组,复合应激组动物每天无规律交替暴露于复合应激原环境中,为期6周。应激结束后,用Morris水迷宫测试大鼠空间学习和记忆成绩,同时用免疫组织化学方法观察海马各亚区Ng表达的变化,并用RT-PCR技术分析各组大鼠海马Ng mRNA水平的变化。结果Morris水迷宫测试显示,应激组动物寻找隐蔽平台潜伏期明显短于对照组(P<0.05);应激组大鼠海马DG和CA3区Ng的蛋白表达水平明显高于对照组(P<0.05),而两组海马CA1区的Ng的免疫反应性无明显差别;与对照组相比,应激组动物的Ng mRNA水平亦明显上调(P<0.05)。结论慢性复合性应激大鼠的学习与记忆能力增强;Ng在海马中的表达和Ng mRNA转录水平增高,提示Ng参与了该增强机制。     

The role of the supramammillary area of the hypothalamus in cognitive functions

The supramammillary area (SUM) of the hypothalamus has wide spread connection with numerous brain structures. It is known that the SUM can control the frequency of the hippocampal theta rhythm, which plays a role in the cognitive functions of the hippocampal formation. In order to examine the role of the specific cells of the SUM in learning and memory, selective cholinergic neurotoxic or excitotoxic lesioned rats of the SUM were tested for spatial memory on the Morris water maze (MWM) test. After the behavior tests, the expression of acetylcholinesterase (AChE) in the hippocampus was studied using the immunohistochemistry. In the MWM test, both lesion of the SUM with 192 IgG-saporin or ibotenic acid produced the impairment of spatial learning and memory. The expression of AChE immunreactive neurons in the hippocampal CA3 region was decreased after injections of 192 IgG-saporin into the SUM. These findings suggest that cholinoceptive cells of the SUM area may play a critical role in the process of learning and memory.     

慢性应激对大鼠学习记忆能力和海马LTP的影响

目的和方法：本研究采用一种多因素的２１ｄ慢性应激动物模型,以Ｙ迷宫和ＬＴＰ为指标,探讨慢性应激对运动学习记忆能力和海马神经突触可塑性的影响。结果：长期慢性应激使大鼠空间学习记忆能力下降,而且,使中枢海马齿状回ＬＴＰ的诱生受到抑制。结论：慢性应激可能使大鼠海马齿状回神经突触可塑性降低,并进一步影响到学习记忆的功能。     

Long-Term Moderate Dose Exogenous Erythropoietin Treatment Protects from Intermittent Hypoxia-Induced Spatial Learning Deficits and Hippocampal Oxidative Stress in Young Rats

Exposure to intermittent hypoxia (IH) is associated with cognitive impairments and oxidative stress in brain regions involved in learning and memory. In earlier studies, erythropoietin (EPO) showed a neuroprotective effect in large doses. The aim of the present study was to explore the effect of smaller doses of EPO, such as those used in the treatment of anemia, on IH-induced cognitive deficits and hippocampal oxidative stress in young rats. The effect of concurrent EPO treatment (500 and 1,000 IU/kg/day ip) on spatial learning and memory deficits induced by long-term exposure to IH for 6 weeks was tested using the Morris water maze (MWM) test and the elevated plus maze (EPM) test. Moreover, the effect on hippocampal glutamate and oxidative stress were assessed. Exposure to IH induced a significant impairment of spatial learning and cognition of animals in both MWM and EPM performance parameters. Moreover, hippocampal glutamate and thiobarbituric acid reactive substances (TBARS) increased while antioxidant defenses (GSH and GSH-Px) decreased. EPO in the tested doses significantly reduced the IH-induced spatial learning deficits in both MWM and EPM tests and dose-dependently antagonized the effects of IH on hippocampal glutamate, TBARS, GSH levels, and GSH-Px activity. Treatment with EPO in moderate doses that used for anemia, concurrently with IH exposure can antagonize IH-induced spatial learning deficits and protect hippocampal neurons from IH-induced lipid peroxidation and oxidative stress-induced damage in young rats, possibly through multiple mechanisms involving a potential antioxidative effect.     

Spatial learning and memory deficits after whole-brain irradiation are associated with changes in NMDA receptor subunits in the hippocampus

Whole-brain irradiation is used for the treatment of brain tumors, but can it also induce neural changes, with progressive dementia occurring in 20-50% of long-term survivors. The present study investigated whether 45 Gy of whole-brain irradiation delivered to 12-month-old Fischer 344 x Brown Norway rats as nine fractions over 4.5 weeks leads to impaired Morris water maze (MWM) performance 12 months later. Compared to sham-irradiated rats, the irradiated rats demonstrated impaired MWM performance. The relative levels of the NR1 and NR2A but not the NR2B subunits of the NMDA receptor were significantly higher in hippocampal CA1 of irradiated rats compared to control rats. No significant differences were detected for these NMDA subunits in CA3 or dentate gyrus. Further analysis of CA1 revealed that the relative levels of the GluR1 and GluR2 subunits of the AMPA receptor and synaptophysin were not altered by whole-brain irradiation. In summary, a clinically relevant regimen of fractionated whole-brain irradiation led to significant impairments in spatial learning and reference memory and alterations in the relative levels of subunits of the NMDA, but not the AMPA, receptors in hippocampal CA1. These findings suggest for the first time that radiation-induced cognitive impairments may be associated with alterations in glutamate receptor composition.     

Acute Physiological Stress Promotes Clustering of Synaptic Markers and Alters Spine Morphology in the Hippocampus

GluA2-containing AMPA receptors and their association with protein kinase M zeta (PKMζ) and post-synaptic density-95 (PSD-95) are important for learning, memory and synaptic plasticity processes. Here we investigated these synaptic markers in the context of an acute 1h platform stress, which can disrupt spatial memory retrieval for a short-term memory on the object placement task and long-term memory retrieval on a well-learned radial arm maze task. Acute stress increased serum corticosterone and elevated the expression of synaptic PKMζ while decreasing synaptic GluA2. Using co-immunoprecipitation, we found that this stressor promotes the clustering of GluA2, PKMζ and PSD-95, which is consistent with effects reported from overexpression of PKMζ in cell culture. Because PKMζ overexpression has also been shown to induce spine maturation in culture, we examined how stress impacts synaptic markers within changing spines across various hippocampal subfields. To achieve this, we employed a new technique combining Golgi staining and immmunohistochemistry to perform 3D reconstruction of tertiary dendrites, which can be analyzed for differences in spine types and the colocalization of synaptic markers within these spines. In CA1, stress increased the densities of long-thin and mushroom spines and the colocalization of GluA2/PSD-95 within these spines. Conversely, in CA3, stress decreased the densities of filopodia and stubby spines, with a concomitant reduction in the colocalization of GluA2/PSD-95 within these spines. In the outer molecular layer (OML) of the dentate gyrus (DG), stress increased both stubby and long-thin spines, together with greater GluA2/PSD-95 colocalization. These data reflect the rapid effects of stress on inducing morphological changes within specific hippocampal subfields, highlighting a potential mechanism by which stress can modulate memory consolidation and retrieval.     

丙二醛对大鼠空间学习、记忆能力及海马CA1区超微结构的影响

研究了氧化应激毒性中间产物丙二醛(MDA)对SD大鼠空间学习、记忆的影响。用Morris水迷宫方法研究发现,经侧脑室注射丙二醛的大鼠在定位航行试验中寻找水下平台的逃避潜伏期极显著地延长,同时在空间探索试验中120s内穿台次数减少,说明较高浓度的丙二醛能导致大鼠的空间学习、记忆能力降低。电镜观察研究发现,处理组大鼠海马CA1区神经元细胞内线粒体变形、嵴消失,说明不同浓度的丙二醛在非氧自由基条件下也能直接对大鼠海马CA1区神经元造成一定程度的损伤。     

Changes in vascular endothelial growth factor (VEGF) induced by the Morris water maze task

The present study was undertaken to evaluate the effects on hippocampal vascular endothelial growth factor (VEGF) levels in rats when they experience hippocampal-dependent spatial learning via the Morris water maze (MWM) task. Rats underwent one of two different versions of the MWM: weak or intensive. After one day of intensive training, a highly sensitive enzyme-linked immunosorbent assay (ELISA) was used to measure VEGF protein levels in the hippocampus, cortex, and serum, and higher levels were found in the trained group compared to a naive control group. VEGF levels also increased in rats that swam only for durations equal to the intensive training periods. In contrast, rats trained under the weaker MWM paradigm for five days showed a decrease in hippocampal VEGF protein level. Mimicking increases in neuronal VEGF in the hippocampus by direct infusion of VEGF into CA1 resulted in up-regulation of the phosphorylation of the cAMP response element-binding (CREB) protein and the Ca²⁺/calmodulin-dependent protein kinases II (CaMKII). These results suggest that VEGF may be a physiological parameter involved in learning procedures that include physical activity.     

东莨菪碱慢性给药大鼠作为老龄相关记忆损害模型的探索

目的对东莨菪碱慢性给药大鼠能否作为老龄相关记忆损害模型进行探索。方法14只1月龄SD大鼠随机分为对照组和东莨菪碱模型组。东莨菪碱模型组大鼠皮下注射东莨菪碱2mg kg,2次日,正常对照组予等量生理盐水,连续21d。然后利用Morris水迷宫(MWM)参照记忆试验进行行为学测试;神经元的特殊染色及电子显微镜技术,观察大鼠海马CA1、CA3区锥体细胞数、超微结构的改变以及突触可塑性变化。结果东莨菪碱组大鼠隐匿平台搜索实验成绩有一定损害;两组大鼠空间探索次数差异无显著性(P>0.05)。两组间海马CA1、CA3区锥体细胞数差异无显著性(P>0.05)。两组大鼠锥体细胞胞体超微结构无差异,但两组大鼠CA1区神经元突触超微结构有轻微变化。结论东莨菪碱慢性给药对大鼠学习记忆能力有一定损害,但对长时记忆无明显影响;对海马神经元结构无明显损害,对神经元突触可塑性有轻微影响。此种动物模型可能不是理想的老年性痴呆或老年相关记忆损害模型。     

早期干预改善缺氧缺血性脑损伤大鼠认知能力及其机制分析

目的研究早期干预对缺氧缺血性脑损伤(HIBD)大鼠学习记忆功能的影响及其作用机制。方法选用SD大鼠建立宫内HIBD动物模型,随机分为非干预组和干预组,非干预组与正常对照组常规饲养,对干预组采取早期触摸和丰富环境刺激。干预28d后,通过三等臂Y型迷宫试验检测各组大鼠的学习记忆功能,而后取大鼠额皮质和海马组织进行病理观察,并采用DNA缺口原位末端标记法(TUNEL反应法)检测凋亡细胞,观察脑组织神经元凋亡情况。结果单纯HIBD组大鼠学习获得与记忆保持能力明显低于正常对照组(P<0·01),但HIBD干预组Y迷宫测试成绩则优于HIBD非干预组(P<0·01)。同时,HIBD非干预组脑额皮质和海马CA1区神经元缺失远较正常组多(P<0·01),而HIBD干预组与HIBD非干预组之间神经元数量的差异则不那么显著。但HIBD干预组脑额皮质和海马神经元凋亡百分率明显低于HIBD非干预组(P<0·01)。结论早期干预可减轻缺氧缺血性损伤脑组织神经细胞凋亡,该作用可能是早期干预促进HIBD大鼠脑功能修复的机制之一。