睡眠剥夺大鼠大脑皮层和海马nNOS表达的改变在其学习记忆损伤中的作用

目的观察睡眠剥夺（SD）后,大鼠学习记忆能力及大脑皮层和海马神经元型一氧化氮合酶（nNOS）蛋白表达的变化。方法采用小平台水环境法建立大鼠SD模型。观察大鼠经过不同时间SD后,各组“Y”迷宫成绩及大脑皮层和海马nNOS阳性神经元的变化情况。结果（1）“Y”迷宫实验：3组SD组的迷宫成绩较正常笼养对照组（CC）分别下降了24．3％、17．6％和41．9％（P〈0．01）。（2）nNOS阳性神经元数目：在皮层,SDld组较CC组增加了8．7％（P〈0．01）,SD2d组和SD3d组较CC组则减少了9．0％和16．0％（P〈0．01）;在海马CA。区,3个SD组较CC组分别减少了9．4％、16．0％和22．0％（P〈0．01）。结论SD可能通过改变大鼠大脑皮层和海马CA．区nNOS蛋白的表达来损害大鼠学习记忆能力。     

脑缺血与慢性应激对依赖海马的学习记忆的影响

目的 对比脑缺血与慢性应激所致认知损害及海马病变的强弱,为临床改善脑卒中后认知障碍(poststroke cognitive impairment,PSCI)提供参考.方法 40只成年雄性SD大鼠平均分为4组:对照组、应激组、缺血组与缺血加应激组,缺血手术采用改良的选择性大脑中动脉栓塞术;应激处理采用连续3周的慢性不可预见性温和应激;Moms水迷宫实验评价依赖海马的学习记忆功能;免疫组织化学染色及半定量RT-PCR观察海马CA3区脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)的表达变化.结果 应激或缺血均可使大鼠学习功能明显下降,表现为与同时点对照组比较,逃避潜伏期显著延长,二者的综合作用更明显.慢性应激对学习功能的影响强于脑缺血损伤.应激或缺血均减弱记忆功能,但二者的作用差异无统计学意义.与对照相比,缺血显著增加海马CA3区BDNF的表达(27.0±2.5与20.1±2.1),应激降低BDNF的表达(15.2±1.8与20.1±2.1),二者综合作用仍显著降低BDNF的表达(8.2±1.5),差异均具有统计学意义(F=52.87,P＜0.05).结论 缺血与应激均降低大鼠学习记忆功能,应激对认知功能的损害高于缺血,而缺血与应激的综合作用对认知功能损害与抑制BDNF表达作用更明显,提示进行PSCI的综合治疗时,要重视心理社会应激干预和抑郁状态的改善.     

糖尿病大鼠海马组织中周期素依赖性激酶5表达的实验研究

目的：分析糖尿病大鼠海马组织中周期素依赖激酶5（CDK5）蛋白表达情况，探讨糖尿病影响学习与记忆的机制。方法：Y-迷宫评估大鼠学习与记忆成绩，用免疫组化法和Western blot检测海马区CDK5蛋白表达。结果：DM组大鼠第4周迷宫作业错误反应次数和全天总反应时间分别为（3．43±2．20）次、（115．42±36．64）s，对照组为（2．17±1．34）次，（90．83±20．27）s；CDK5蛋白表达相对水平为15．62±7．07，对照组为20．61±5．63，两组间差异有统计学意义（P〈0．05）。结论：糖尿病大鼠CDK5蛋白表达水平下降，学习记忆能力下降，提示CDK5可能参与了学习记忆过程。     

铅暴露鼠学习记忆障碍相关机制的研究

目的 研究铅暴露大鼠海马神经细胞精氨酸加压素(AVP)、生长抑素(SS)的阳性表达,及其与学习记忆障碍的关系.方法 将健康两月龄SD大鼠60只,随机分为对照组、染铅组,每组30只,染铅动物饮用0.1%醋酸铅去离子水3个月,制成慢性染铅大鼠模型;对照组饮用去离子水.Y-迷宫试验检测两组大鼠的学习和记忆能力,采用免疫组化方法测定大鼠海马AVP和SS阳性神经元数,观察铅暴露对其阳性表达的影响.结果 染铅组大鼠学习记忆能力较对照组明显减低(P<0.01),海马CA1区AVP 和SS阳性神经元数量均明显减少(均P<0.01),CA3区AVP(P<0.05)和SS(P>0.05)阳性神经元数量亦减少,但不如CA1区明显.结论 铅暴露大鼠学习记忆能力的减低可能与海马神经细胞AVP和SS的阳性表达减少有关.     

γ-氨基丁酸对慢性脑缺血致血管性痴呆大鼠学习记忆能力的影响

目的观察γ-氨基丁酸（GABA）对慢性脑缺血致血管性痴呆（VD）大鼠学习记忆能力及海马CA1区神经元形态学的影响。方法将SD大鼠随机分为假手术组、模型组、GABA组,采用双侧颈总动脉永久性结扎法建立VD模型。GABA组术后腹腔注射GABA0.5g.kg-1.d-1,连续注射60d;用Morris水迷宫实验检测大鼠空间学习记忆能力;Nissl染色观察大鼠海马CA1区神经元形态学变化。结果 GABA能明显改善VD大鼠学习记忆能力,也能减轻海马CA1区神经元损伤。结论 GABA能改善慢性脑缺血致VD大鼠的学习记忆能力,减轻海马神经元损伤可能是其机制之一。     

缺血后处理对脑缺血大鼠学习记忆能力的影响

目的研究缺血后处理(IP)对大鼠脑缺血再灌注损伤后的学习和记忆能力的影响,探讨各组大鼠脑缺血再灌注后海马CA1区β淀粉样蛋白前体(APP)表达。方法将48只雄性SD大鼠随机分为3组:假手术组、对照组和缺血后处理组(IP组),每组16只大鼠。术后用Morris水迷宫方法测定大鼠认知记忆能力变化。3组大鼠脑组织切片行HE染色和APP染色,并行统计学分析。结果 Morris水迷宫试验显示,对照组大鼠训练第1~4天逃避潜伏期长于IP组(P 0. 01);跨越原平台次数IP组明显多于对照组(P 0. 05)。HE染色结果显示,对照组大鼠海马CA1区神经元细胞脱失明显,而IP可减轻这种形态学改变。免疫组化结果显示,在脑缺血再灌注144 h后对照组中APP表达明显高于假手术组(P 0. 01); IP组海马CA1区APP表达较对照组减少(P 0. 05)。结论缺血后处理可通过抑制APP的表达改善缺血再灌注后大鼠的记忆减退。     

血管性痴呆小鼠海马细胞外信号调节激酶免疫组化表达及其意义

目的探讨血管性痴呆小鼠海马CA1区锥体细胞细胞外信号调节激酶1（extracellular signal—regulated kinase 1，ERKI）的免疫组化表达及其意义。方法采用双侧颈总动脉线结反复缺血-再灌注法制备血管性痴呆（VaD）小鼠模型，共设健康对照组、假手术组及VaD模型组，利用跳台试验和水迷宫试验观测其行为学改变，应用免疫组化技术观测其海马CA1区锥体细胞ERK1的表达变化，对小鼠学习成绩和记忆成绩与ERK1免疫反应阳性锥体细胞免疫组化评分进行相关性分析。结果VaD模型组小鼠学习、记忆成绩低于健康对照组和假手术组（P〈0．05）。VaD模型组小鼠ERK1免疫反应阳性锥体细胞免疫组化评分（13．38&#177;3．32）较健康对照组（21．21&#177;9．15）和假手术组（21．00&#177;7．21）明显减少（P〈0．01），而且各组小鼠海马ERK1免疫反应阳性锥体细胞免疫组化评分与小鼠学习、记忆的各项参数存在相关关系。结论VaD小鼠海马CA1区锥体细胞ERK1表达减少可能是VaD小鼠学习、记忆成绩下降的分子机制之一。     

尿酸对阿尔茨海默病大鼠学习记忆能力的影响及其机制

目的 观察尿酸对阿尔茨海默病(Alzheimer disense,AD)大鼠学习记忆能力的影响,并探讨作机制.方法 Morris水迷宫实验筛选出90只大鼠,随机分为空白对照组,模型对照组.尿酸处理组(1～4组),每组15只.Aβ1-42海马注射制作AD模型,用Morris水迷宫实验观察干预前后大鼠空间学习记忆能力的变化,丙二醛(malondialdehyde,MDA)试剂盒测定海马区MDA的含量;免疫组化染色测定半胱氨酸天冬氨酸蛋白酶-3(caspase-3)的表达.结果 与空白对照组比较,模型对照组大鼠空间学习记忆能力下降(P<0.01),海马区MDA含量和caspase-3明显增高(P<0.01);与模型对照组比较,2种剂量尿酸处理组大鼠的学习记忆能力明显改善(P<0.01).海马区MDA和caspase-3的表达减少(P<0.01).结论 尿酸具有改善AD大鼠空间学习记忆作用,可能与抗氧化应激作用及抑制海马中easpase-3表达有关.     

雌二醇对血管性痴呆大鼠海马CA1区GFAP表达的影响

目的研究17β-雌二醇对血管性痴呆（vascular dementia，VD）大鼠海马CA1区GFAP表达的影响，探讨雌激素对血管性痴呆大鼠中枢神经系统保护作用的机制。方法采用结扎双侧颈总动脉方法制备血管性痴呆动物模型，腹腔注射不同剂量17β-雌二醇60d后，应用γ迷宫检测各组VD大鼠认知功能以及免疫组化法等检测大鼠大脑海马CA1区GFAP表达的变化。结果腹腔注射17β-雌二醇60d后，大鼠认知功能显著改善；学习、记忆功能测试30次的正确次数较实验对照组明显增高（P〈0．05），造模60d后的大鼠，其脑内CA1区GFAP免疫阳性细胞数较假手术组显著增高，而雌二醇组大鼠CA1区GFAP免疫阳性细胞数较实验对照组显著减少。结论雌激素补充疗法能选择性影响血管性痴呆大鼠脑内CA1区GFAP阳性细胞，并有可能影响学习和记忆能力。     

阿尔茨海默病大鼠模型海马MAPK的表达

目的探讨丝裂酶原激活蛋白激酶（mitogen activated protein kinase，MAPK）在阿尔茨海默病（Alzheimer’s diease，AD）发病中的变化及其可能机制。方法将β-淀粉样肽（beta—amyloid peptide，Aβ）1-40 1μl（10μg/μl）在立体定位仪下注人大鼠海马建立大鼠AD模型，2周后测水迷宫潜伏期、长时程增强（long term potentiation，LTP）、免疫组化SABC法检测MAPK的蛋白表达，并应用显微图像分析系统对二者的表达进行分析。结果AD模型组AB注射2周后，水迷宫潜伏期与模型组术前及对照组相比显著延长（P〈0．05）；模型组刺激前后fEPSP斜率变化及高频刺激增加的幅值与对照组相比显著下降（P〈0．01）；模型组海马CA，区、CA，区MAPK蛋白的表达显著降低（P〈0．05或P〈0．01）。结论AB可能通过抑制MAPK信号通路，导致大鼠海马LTP降低和学习记忆功能减退，参与AD学习记忆障碍和痴呆形成。     

行为训练对双侧海马梗死大鼠学习记忆与NCAM的影响

目的探讨行为训练对双侧海马梗死大鼠空间学习记忆功能恢复及海马神经细胞粘附因子(NCAM)的影响及其作用机制。方法30只SD大鼠采用光化学诱导法制作双侧海马CA1区梗死模型,于24h后随机分为行为训练组和制动组,于造模3d后分别给予行为训练或制动,在大鼠造模后3d、行为训练后7d、14d和21d时进行学习记忆能力测试。并于不同时间取脑进行免疫组织化学染色,观察其梗死灶海马周围NCAM含量的变化。结果行为训练组学习记忆能力评估均优于制动组(P<0.05),海马NCAM含量均较制动组增多。结论行为训练可促进大鼠空间学习记忆能力的恢复,其作用机制可能与海马NCAM的增多有关。     

海人酸诱导颞叶癫癎大鼠海马中GAP-43和NCAM的表达变化以及托吡酯的干预作用

目的研究海人酸（KA）对大鼠海马中生长相关蛋白-43（GAP-43）和神经细胞粘附分子（NCAM）表达的影响，以及托吡酯（TPM）对其的干预作用。方法将48只大鼠随机分成生理盐水（NS）组、4mgKA组、10mgKA组和10mgKA＋TPM组（n=12），建立KA诱导颞叶癫癎大鼠模型和TPM干预模型，观察大鼠行为学改变，并通过RT-PCR和WesternBlot的方法测定各组大鼠海马中GAP-43及NCAM的mRNA和蛋白表达水平。结果大鼠建模成功；4mgKA组、10mgKA组大鼠GAP-43及NCAM的mRNA和蛋白表达水平明显高于NS组（P〈0．01），且10mgKA组高于4nagKA组（P〈0．01）；10mgKA＋TPM组大鼠的GAP-43和NCAM表达明显低于10mgKA组（P〈0．01）。结论KA能够诱导致癎大鼠海马GAP-43和NCAM表达上调，且与KA剂量有关，而TPM能够抑制KA诱导的GAP-43和NCAM的表达上调。     

托吡酯对戊四氮点燃慢性癫(癎)大鼠海马神经细胞黏附分子的影响

目的:探讨神经元活化在癫发生、发展中的作用及托吡酯对其的影响。方法:采用戊四氮制备慢性癫模型,利用托吡酯干扰,选取不同时间点,观察大鼠行为学变化及神经细胞黏附分子在海马回的表达(免疫组织化学染色)。结果:托吡酯组点燃率在27d明显低于模型组;模型组及托吡酯组神经细胞黏附分子表达增加,并随时间延长明显;而不同时间点该表达的增加程度,托吡酯组均低于模型组。结论:神经细胞黏附分子表达的增加,说明出现了神经元活化及脑可塑性变化,而托吡酯明显地抑制了该表达的增加。     

Effects of neonatal stress on markers of synaptic plasticity in the hippocampus: Implications for spatial memory

Early stressful adverse situations may increase the vulnerability to cognitive deficits and psychiatric disorders, such as depression. Maternal separation (MS) has been used as an animal model to study changes in neurochemistry and behavior associated with exposure to early‐life stress. This study investigated the effects of neonatal stress (MS) on the expression of synaptic plasticity markers in the hippocampus and a purported relationship to cognitive processes. Spatial learning (Morris water maze) significantly increased the expression of total levels of the neural cell adhesion molecule (NCAM), as well as its three major isoforms (NCAM‐120, ‐140, and ‐180) both in the control and MS groups. Interestingly, these increases in NCAM expression after learning were lower in MS animals when compared with control rats. MS induced a significant decrease in total levels of NCAM, and specifically, in the NCAM‐140 isoform expression. In the hippocampus of MS rats there was a significant decrease in brain‐derived neurotrophic factor and synaptophysin mRNA densities. Cell proliferation, measured as BrdU‐positive cells, was also decreased in the dentate gyrus of MS rats. Altogether these results suggest that MS can alter normal brain development, providing a potential mechanism by which early environmental stressors may influence vulnerability to show cognitive impairments later in life. © 2009 Wiley‐Liss, Inc.     

Olfactory learning-related NCAM expression is state, time, and location specific and is correlated with individual learning capabilities

The notion that long-term synaptic plasticity is generated by activity-induced molecular modifications is widely accepted. It is well established that neural cell adhesion molecule (NCAM) is one of the prominent modulators of synaptic plasticity. NCAM can be polysialylated (PSA-NCAM), a reaction that provides it with anti-adhesion properties. In this study we have focused on NCAM and on its polysialylated state, and their relation to learning of an olfactory discrimination task, which depends on both the piriform (olfactory) cortex and hippocampus. We trained rats to distinguish between pairs of odors until rule learning was achieved, a process that normally lasts 6-8 days. At four time points, during training and after training completion, synaptic NCAM and PSA-NCAM expression were assessed in the piriform cortex and hippocampus. We report that NCAM modulation is specific to PSA-NCAM, which is upregulated in the hippocampus one day after training completion. We also report a correlation between the performance of individual rats in an early training stage and their NCAM expression, both in the piriform cortex and hippocampus. Since individual early performance in our odor discrimination task is correlated with the performance throughout the training period, we conclude that early NCAM expression is associated with odor learning capability. We therefore suggest that early synaptic NCAM expression may be one of the factors determining the capability of rats to learn.     

Causal evidence for the involvement of the neural cell adhesion molecule,NCAM, in chronic stress‐induced cognitive impairments

In rodents, chronic stress induces long‐lasting structural and functional alterations in the hippocampus, as well as learning and memory impairments. The neural cell adhesion molecule (NCAM) was previously hypothesized to be a key molecule in mediating the effects of stress due to its role in neuronal remodeling and since chronic stress diminishes hippocampal NCAM expression in rats. However, since most of the evidence for these effects is correlative or circumstantial, we tested the performance of conditional NCAM‐deficient mice in the water maze task to obtain causal evidence for the role of NCAM. We first validated that exposure to chronic unpredictable stress decreased hippocampal NCAM expression in C57BL/6 wild‐type mice, inducing deficits in reversal learning and mild deficits in spatial learning. Similar deficits in water maze performance were found in conditional NCAM‐deficient mice that could not be attributed to increased anxiety or enhanced corticosterone responses. Importantly, the performance of both the conditional NCAM‐deficient mice and chronically stressed wild‐type mice in the water maze was improved by post‐training injection of the NCAM mimetic peptide, FGLs. Thus, these findings support the functional involvement of NCAM in chronic stress‐induced alterations and highlight this molecule as a potential target to treat stress‐related cognitive disturbances. © 2009 Wiley‐Liss, Inc.     

文拉法辛对慢性应激抑郁大鼠海马区可塑性相关蛋白mRNA表达的影响

目的 观察文拉法辛对慢性应激抑郁大鼠海马区可塑性相关蛋白mRNA表达的影响.方法 用慢性不可预见应激(CUS)方法建立大鼠抑郁模型,给予2种剂量(5 mg/kg体质量和10 mg/kg体质量)的抗抑郁剂文拉法辛,用反转录-聚合酶链反应检测大鼠海马区脑源性神经营养因子(BDNF)、转录因子环磷腺苷反应元件结合蛋白(CREB)及神经细胞黏附分子(NCAM)mRNA表达的变化.正常对照组、抑郁模型组、抑郁模型后注射生理盐水14 d组及28 d组各10只,抑郁模型后小剂量文拉法辛(5 mg/kg体质量)治疗14 d组及28 d组、抑郁模型后大剂量文拉法辛(10 mg/kg体质量)治疗14 d组及28 d组各11只.结果 抑郁模型大鼠体质量、蔗糖水消耗量及旷场实验结果均明显低于正常对照组,提示抑郁模型大鼠在第28天建立成功.慢性不可预见应激28 d后,抑郁模型大鼠海马区BDNF(0.18±0.09)、CREB(0.10±0.05)及NCAM(0.08±0.04)mRNA表达水平均明显低于正常组[吸光度比值分别为(0.41±0.12)、(0.26±0.05)及(0.24±0.08);P均＜0.05 ].5 mg/kg体质量文拉法辛明显增加海马区3种可塑性相关蛋白mRNA的表达;10 mg/kg文拉法辛轻度降低海马区3种可塑性相关蛋白mRNA的表达.结论 文拉法辛在一定剂量范围内调节海马区的神经可塑性,BDNF、CREB及NCAM在抑郁症的病因及治疗中发挥重要作用.     

Acute stress-induced impairment of spatial memory is associated with decreased expression of neural cell adhesion molecule in the hippocampus and prefrontal cortex.

BACKGROUND: There is an extensive literature describing how stress disturbs cognitive processing and can exacerbate psychiatric disorders. There is, however, an insufficient understanding of the molecular mechanisms involved in stress effects on brain and behavior. METHODS: Rats were given spatial memory training in a hippocampus-dependent water maze task. We investigated how a fear-provoking experience (predator exposure) would affect their spatial memory and neural cell adhesion molecule (NCAM) levels in the hippocampus, prefrontal cortex (PFC), amygdala, and cerebellum. RESULTS: Whereas the control (nonstress) group exhibited excellent memory for the hidden platform location in the water maze, the cat-exposed (stress) group exhibited a profound impairment of memory and a marked suppression of levels of the NCAM-180 isoform in the hippocampus. Predator stress produced a more global reduction of NCAM levels in the PFC but had no effect on NCAM levels in the amygdala and cerebellum. CONCLUSIONS: This work provides a novel perspective into dynamic and structure-specific changes in the molecular events involved in learning, memory, and stress. The selective suppression of NCAM-180 in the hippocampus and the more general suppression of NCAM in the PFC provide insight into the mechanisms underlying the great sensitivity of these two structures to be disturbed by stress.     

Stress alleviates reduced expression of cell adhesion molecules (NCAM, L1), and deficits in learning and corticosterone regulation of apolipoprotein E knockout mice

Cell adhesion molecules (CAMs) involved in synaptic changes underlying learning and memory processes, are implicated in the effect of stress on behavioural performance. The present study was designed to test the hypothesis that (i) expression of CAMs is apolipoprotein E‐ (apoE) genotype dependent and (ii) repeated exposure to stress modulates the synthesis of CAMs in an apoE‐genotype dependent manner. Using ELISA we tested this hypothesis and measured expression of NCAM and L1 in different brain regions of naïve and stressed apolipoprotein E‐knockout (apoE0/0) and C57Bl6 (wild‐type) mice. Naïve apoE0/0 mice had elevated basal morning corticosterone and ACTH concentrations and decreased expression of NCAM and L1 compared to wild‐type mice. Repeated exposure of mice to rats, as the common stressor, alleviated the reduction in expression of CAMs in apoE0/0 mice; seven days after the last rat exposure, expression of NCAM was increased in frontal brain and hippocampus whereas expression of L1 was increased in hippocampus and cerebellum. Rat stress attenuated the elevation of basal morning corticosterone concentration in apoE0/0 mice towards concentrations detected in wild‐type mice. Moreover, rat stress improved learning and memory of apoE0/0 mice in the water maze. In conclusion, repeated exposure to stress eliminated apoE‐genotype‐related differences in expression of CAMs. Under these same conditions the differences in cognitive performance and corticosterone concentrations were abolished between wild type and apoE0/0 mice.