NMDA受体在焦虑症发病机制的研究进展

伴随社会生活和工作压力的增大,常见精神类疾病焦虑症的发病率逐年攀升。焦虑症的发病机制非常复杂,迄今尚未完全阐明。本文概述了焦虑症发病机制与NMDA受体不同亚型的关系。NMDA受体主要广泛分布于脑、脊髓和周围神经系统。NR1广泛分布于中枢神经,在NR2D亚基敲除小鼠中,NR1和NR2D的相互影响可能参与了焦虑样行为。NR2A与NR2B是NMDA受体的两个重要亚基,NR2B的高选择性拮抗剂艾芬地尔在小鼠的高架十字迷宫实验中发挥了抗焦虑功效。将小鼠全脑的NR2C基因用NR2B替代之后,1月龄变异小鼠的高架十字迷宫实验显示有明显的非条件性焦虑行为,表明NR2B和NR2C均可能参与焦虑的发生。因此,深入阐明调控NMDA受体亚基组成的确切作用机制,将有助于探索焦虑症潜在治疗靶点的发现,并针对性地开展新药的研发。     

间歇性低氧预处理对创伤后应激障碍模型小鼠恐惧和焦虑行为的改善作用

间歇性低氧(intermittent hypoxia, IH)对高血压、心肌梗死、脑缺血以及抑郁症有一定预防和治疗作用,但IH对创伤后应激障碍(post-traumatic stress disorder, PTSD)的作用尚不清楚。本研究采用不可逃避足底电击联合场景再现制备PTSD小鼠模型,通过旷场测试、高架十字迷宫测试及条件性恐惧测试反映其恐惧和焦虑水平;通过Y迷宫测试反映其空间记忆能力;通过免疫组化染色检测海马、杏仁核和内侧前额叶皮层Fos阳性神经元的数量;采用Western blot方法检测海马、杏仁核和内侧前额叶皮层低氧诱导因子1α(hypoxia inducible factor-1α, HIF-1α)、血管内皮生长因子(vascular endothelial growth factor,VEGF)和脑源性神经营养因子(brain derived neurotrophic factor, BDNF)蛋白表达水平。结果显示,IH与模型(电击)对高架十字迷宫测试中进入开放臂次数所占百分比、条件性恐惧测试中僵住时间和排便数量存在交互作用,IH能增加PTSD模型小鼠在高架十字迷宫中开放臂运动次数,减少条件性恐惧测试中僵住时间和排便数量。同时,IH预处理能减少PTSD模型小鼠海马、杏仁核和内侧前额叶皮层Fos阳性神经元的数量,增加这些脑组织中HIF-1α、VEGF和BDNF蛋白的表达水平。以上结果表明,IH预处理对PTSD模型小鼠恐惧和焦虑行为有改善作用,提示IH有可能成为预防PTSD的有效手段。     

小鼠动物实验方法系列专题(五) 应用高架十字迷宫分析小鼠焦虑行为

高架十字迷宫(the elevated plus maze,EPM)是研究小鼠焦虑行为的重要实验,本文介绍了EPM的原理和实验步骤。将小鼠置于开臂闭臂接合处,面向开臂,通过录像记录分析小鼠在EPM的表现。结果发现,两种小鼠均可成功完成实验,C57小鼠在EPM内较不活跃,闭臂滞留时间占总时间百分比显著高于129Sv小鼠。应用EPM可以简单直观地分析小鼠焦虑行为。     

Wistar大鼠幼年期丰富环境刺激对其社会竞争行为的影响

目的：探讨大鼠幼年期丰富环境经历对其成年后焦虑样行为和社会竞争行为的影响。方法：幼年期Wistar大鼠（生后21天）分为标准饲养组（对照组）和丰富环境刺激（EE）组。对照组为持续在标准实验室饲养条件下饲养;丰富环境组为生后21天至行为学检查时持续在丰富环境下饲养。在生后70天进行行为学检测：采用高架十字迷宫方法测试焦虑样行为;采用社会优势管道试验观察社会竞争性行为。结果：高架十字迷宫实验结果显示,与对照组相比,丰富环境组在开放臂的时间和次数显著增加;优势管道实验结果显示丰富环境刺激组大鼠的社会竞争力明显下降。结论：大鼠幼年期丰富环境刺激可改善大鼠的焦虑样情绪,但导致大鼠社会竞争力下降。     

复合不育剂EP-1对小鼠空间记忆与焦虑行为的影响

EP-1是由炔雌醚和左炔诺孕酮按照1∶2的比例配制而成的一种用于鼠类不育控制的激素类复合不育剂,对鼠类的繁殖及繁殖行为等有一定影响,但对鼠类空间学习与记忆、焦虑行为等非繁殖行为的影响还没有报道。为此,用0(对照)、1.0、2.0、3.0 mg/kg剂量的EP-1对昆明小鼠(Mus musculus)进行灌胃处理,然后用Morris水迷宫和高架十字迷宫分别测定其空间记忆、焦虑行为。结果发现灌胃后15 d,剂量为2.0 mg/kg的EP-1使小鼠空间记忆能力显著下降,但30 d后其空间记忆能力有所恢复,表明2.0 mg/kg剂量的EP-1可以在一定时间范围内降低小鼠的空间记忆能力。但不同剂量的EP-1对小鼠焦虑行为无显著影响。该结果可以为从对非繁殖行为的影响的角度研究EP-1对鼠类的作用提供一定启示。     

T细胞调节天然免疫新发现

中国科学家发现,无法产生神经递质5-羟色胺的小鼠焦虑程度较正常小鼠低,但保持恐惧记忆的时间更长。5-羟色胺是与许多行为有关的重要信号传导分子,和抑郁、焦虑及创伤后应激障碍特别有关。研究者比较了缺乏5-羟色胺的小鼠和对照组小鼠,缺乏5-羟色胺的小鼠在高架迷宫的开口部分游荡时比对照组小鼠放松,这提示它们焦虑程度较低。     

社会隔离对小鼠焦虑水平及神经活动的影响

目的 探究不同饲养条件下小鼠Mus musculus的焦虑行为特征及神经活动特征.方法 对21日龄的雄性CD-1小鼠进行社会隔离(SI)或社会群居(SG)饲养处理2周后,采用经典的焦虑行为范式(高架十字迷宫)进行测试,并同步采集内侧前额叶(mPFC)、内侧杏仁核(MeA)、腹内侧下丘脑(VMH)等脑区的局部场电位(LF...     

淀粉样β蛋白抑制大鼠海马theta节律并致行为脱抑制和空间记忆损伤

海马神经元网络振荡与哺乳动物学习记忆、焦虑及行为抑制密切相关。阿尔茨海默病患者早期表现出的认知功能减退及行为脱抑制,极可能与海马内沉积的淀粉样β蛋白(amyloid β protein,Aβ)损伤了海马神经元网络电活动有关,但海马注射Aβ能否在伤害学习记忆功能的同时也引起行为脱抑制和改变神经元同步化活动,仍缺乏足够的动物实验证据。本研究利用Morris水迷宫、高架十字迷宫和在体局部场电位记录技术,观察了海马注射Aβ1–42寡聚体对大鼠空间学习记忆和行为抑制活动的影响,并分析了海马theta节律的改变。结果表明,与对照组相比,海马注射Aβ1–42寡聚体两周后:(1)大鼠在高架十字迷宫中焦虑性减低,出现明显的行为脱抑制现象,去开臂次数和在开臂停留时间均明显增加;(2)大鼠空间学习、记忆严重受损,水迷宫定位航行实验中寻找水下平台的潜伏期明显延长,空间探索实验中在原平台象限的游泳时间百分比明显减小;(3)大鼠海马CA1区theta节律压抑,由夹尾刺激诱导的theta节律的功率峰值明显减低,而theta节律功率峰值对应的频率值未发生改变。以上结果表明,海马注射Aβ1–42寡聚体可同时引起大鼠行为脱抑制、空间记忆损伤和海马theta节律压抑。这提示,AD患者出现的学习记忆能力障碍和精神行为异常很可能与Aβ对海马神经元网络theta节律活动的压抑以及由此引起的突触可塑性下调有关。     

妊娠期和哺乳期双酚A暴露对幼年子代小鼠焦虑和抑郁行为的影响

双酚A(bisphenol-A,BPA)对脑和行为发育的低剂量效应已引起广泛关注。本研究分别于妊娠最后2周和分娩后前2周母鼠灌胃BPA(0.4和4 mg/kg.d),然后以旷场、高架十字迷宫、明暗箱、镜子迷宫、强迫游泳和被动回避箱等模型,分别测试幼年期(生后21～28 d)子代小鼠的行为,探讨围生期不同阶段的BPA暴露对幼年仔鼠自发活动、探究、焦虑、抑郁和被动回避记忆等行为的影响。结果表明,围生期不同阶段的BPA暴露对这些行为的影响不同,主要表现为:妊娠期BPA暴露促进幼年仔鼠的活动性,减弱其焦虑状态,提高雄性仔鼠的探究能力,促进雌性仔鼠的被动回避记忆;哺乳期BPA暴露减少幼年仔鼠的活动性,但对其焦虑行为的影响相对较弱,不影响仔鼠的探究能力和被动回避记忆;而妊娠期和哺乳期BPA暴露均加剧幼年仔鼠的抑郁行为。以上结果提示,妊娠期和哺乳期BPA暴露均可影响幼年仔鼠的焦虑、抑郁、被动回避记忆等多种行为,而妊娠期可能是BPA影响的更敏感时期。     

ω-3 多不饱和脂肪酸对PTSD-SPS 大鼠行为学影响的研究

目的:观察饲料中添加ω-3PUFAs对PTSD-SPS大鼠焦虑/抑郁行为的防护作用。方法:将40只健康成年雄性SD大鼠随机分为正常对照组、PTSD-SPS模型组、60%ω-3PUFAs+PTSD-SPS模型组1、60%ω-3PUFAs+PTSD-SPS模型组2。采用高架十字迷宫实验和旷场实验评价实验组大鼠的焦虑/抑郁行为变化。结果:与对照组相比,SPS模型组大鼠进入开放臂的次数比例和时间比例明显减少;中央格停留时间明显缩短(5.56±0.21)s,穿格次数明显减少(30.23±5.96)次,差异均显著(P<0.05)。与SPS模型组相比,60%ω-3PUFAs的SPS组大鼠进入开放臂的次数比例和时间比例明显增加;中央格停留时间明显延长(9.88±1.14)s,穿格次数明显增加(43.22±4.35)次,差异均显著(P<0.05);与对照组相比没有显著差异。结论:膳食补充ω-3多不饱和脂肪酸可以降低PTSD-SPS大鼠焦虑/抑郁程度。     

Differences in anxiety-related behavior between apolipoprotein E-deficient C57BL/6 and wild type C57BL/6 mice

The influence of ApoE gene deletion on the anxiety state has not been previously investigated. The elevated plus maze was used in this study to determine differences in anxiety-related behavior between apoE-deficient and wild type C57BL/6 mice. The apoE-deficient mice demonstrated less anxiety on the elevated plus maze by spending more time in the open arms of the elevated plus maze compared to wild type mice (p<0.001). Additionally, female apoE-deficient mice visited the open arm of the maze more often than their apoE-deficient male counterpart (p<0.05). The anxiety state and/or sex are possible variables to be considered when designing physiological and/or behavioral studies involving mice that are apoE-deficient.     

Testing for episodic-like memory in rats in the absence of time of day cues: replication of Babb and Crystal

Two experiments were performed to look for evidence of episodic-like memory in rats. On each of a series of trials on an eight-arm radial maze, rats in two groups entered four open arms in Phase 1, with reward pellets on three arms and a favored reward (chocolate in Experiment 1 and cheese in Experiment 2) on the remaining arm. Phase 2 retention tests were given 30 min or 4 h after Phase 1, with all eight arms open. The four arms not entered in Phase 1 all contained reward pellets, and the three arms that contained pellets in Phase 1 were empty. In the replenish short group, the favored reward was replenished at the same location where it was found in Phase 1 at the 30 min retention interval but was absent (Experiment 1) or degraded (Experiment 2) at the 4 h retention interval. In the replenish long group, the favored reward was replenished at the 4 h retention interval but not at the 30 min retention interval. Over a number of daily trials that randomly mixed short and long delays, rats in both experiments learned to return earlier to the arm containing the favored reward at the retention interval when it was replenished than at the retention interval when it was absent or degraded. These results replicate earlier findings [Babb, S.J., Crystal, J.D., 2005, Discrimination of what, when, and where: implications for episodic-like memory in rats. Learn. Mot., 36, 177-189] and provide evidence of episodic-like memory in rats.     

The use of the elevated plus maze as an assay of anxiety-related behavior in rodents

The elevated plus maze is a widely used behavioral assay for rodents and it has been validated to assess the anti-anxiety effects of pharmacological agents and steroid hormones, and to define brain regions and mechanisms underlying anxiety-related behavior. Briefly, rats or mice are placed at the junction of the four arms of the maze, facing an open arm, and entries/duration in each arm are recorded by a video-tracking system and observer simultaneously for 5 min. Other ethological parameters (i.e., rears, head dips and stretched-attend postures) can also be observed. An increase in open arm activity (duration and/or entries) reflects anti-anxiety behavior. In our laboratory, rats or mice are exposed to the plus maze on one occasion; thus, results can be obtained in 5 min per rodent.     

Naltrexone potentiates both amnestic and anxiolytic effects of chlordiazepoxide in mice

Studies have suggested that opioid antagonists potentiate the anxiolytic effect but not the amnestic action of chlordiazepoxide (CDZ). We investigated the effects of naltrexone (NAL) on the anxiolytic and amnestic effects of CDZ in mice tested in the plus-maze discriminative avoidance task (DAT). Mice are conditioned to choose between two enclosed arms (one of which aversive) while avoiding the two open arms of the apparatus. This task measures memory (time spent in the aversive vs. time in the non-aversive enclosed arms) and anxiety (time spent in the open arms). Mice treated with saline (SAL) or 5 mg/kg NAL, and SAL or 2.5 mg/kg CDZ were submitted to DAT training. The test was performed 24 h later, without aversive stimuli. In the training, NAL + CDZ group showed higher percent time spent in the open arms than all the other groups. In the test, NAL + CDZ (but not SAL + CDZ) group showed higher percent time spent in the aversive enclosed arm than SAL + SAL and NAL + SAL groups. The data suggest that NAL potentiates the small decreases in anxiety and retention induced by a subeffective dose of CDZ.     

Effect of Acupuncture on Hypothalamic�CPituitary�CAdrenal System in Maternal Separation Rats

The maternal separation (MS) animal model has been widely used to study early life stress and several psychiatric conditions such as depression and anxiety. In this study, we investigated the effect of acupuncture on anxiety-related behaviors and hypothalamic-pituitary-adrenal (HPA) system in MS-induced early life stress of Sprague-Dawley rat pups (14-21 postnatal days). For determining anxiety-related behaviors, the elevated plus-maze test was performed. The effects of acupuncture on the activation of stress were measured by assessing plasma levels of corticosterone (CORT) and adrenocorticotropin hormone (ACTH). The hypothalamic immunoreactivity (IR) of arginine vasopressin (AVP) was also examined. Acupuncture was conducted at acupoint HT7, which is used to treat mental disorders in Oriental medicine, for seven consecutive days. Acupuncture significantly decreased the frequencies of open arm entries and the amount of time spent in the open arms in MS rats. In addition, acupuncture reduced CORT and ACTH levels in plasma of MS rats, and AVP-IR in the hypothalamic paraventricular nucleus of MS rats. In conclusion, acupuncture reduced anxiety-related behaviors and modulated the HPA system. These findings suggest that acupuncture at HT7 may be useful as a therapeutic treatment in MS-induced early life stress.     

Acute stress disrupts performance of zebrafish in the cued and spatial memory tests: the utility of fish models to study stress-memory interplay

The zebrafish (Danio rerio) has emerged as a promising model organism for affective or cognitive neuroscience research, and may be useful to study the interplay between memory and anxiety-related states. To assess the effects of acute psychological stress on spatial and cued memory, adult zebrafish were trained in an aquatic plus-maze for 14 days using food bait as a reward. Two ecologically relevant stressors (alarm pheromone or Indian leaf fish exposure) were applied to acutely stress zebrafish immediately prior to the final (testing) trial. Overall, acute single inescapable stress markedly impaired spatial and cued memory in zebrafish plus-maze test, reducing the number of correct arm entries and time spent in the target arm. This observation parallels rodent and clinical literature on memory-impairing effects of acute stress, strongly supporting the utility of zebrafish in neurobehavioral research.     

Strain differences in activity and emotionality do not account for differences in learning and memory performance between C57BL/6 and DBA/2 mice

This study examined emotionality, activity, learning and memory, as well as the influence of emotionality and activity on learning and memory performance in C57BL/6 and DBA/2 mice using a mouse-test battery. DBA/2 mice performed more poorly than C57BL/6 mice in complex learning tasks such as the water maze and object recognition tasks. In contrast, C57BL/6 mice showed attenuated habituation to novelty in the open field apparatus and poorer performance in the step-down passive avoidance task. The C57BL/6 mice were less exploratory and more anxious than the DBA/2 mice. The anxiety score (open arm entries in the elevated plus maze) was significantly correlated with all measures of learning and memory in the object recognition task, and some measures in the passive avoidance and water maze tasks. Analysis of covariance (with open arm entries as a covariate) revealed that some measures on trial 1 of the object recognition task, but not the memory scores on trial 2, were confounded by anxiety. No confounding factors of anxiety were found in the water maze or passive avoidance tasks. Similar results were obtained with the activity scores (line crossing and rearing in the open field). In conclusion, strain differences in activity and anxiety did not account for strain differences in learning and memory performance of C57BL/6 and DBA/2 mice. Nonetheless, the importance of using complete behavioural test batteries should be stressed to ensure that strain differences in learning and memory tasks are not confounded by non-cognitive factors.     

Connecting Anxiety and Genomic Copy Number Variation: A Genome-Wide Analysis in CD-1 Mice

Genomic copy number variants (CNVs) have been implicated in multiple psychiatric disorders, but not much is known about their influence on anxiety disorders specifically. Using next-generation sequencing (NGS) and two additional array-based genotyping approaches, we detected CNVs in a mouse model consisting of two inbred mouse lines showing high (HAB) and low (LAB) anxiety-related behavior, respectively. An influence of CNVs on gene expression in the central (CeA) and basolateral (BLA) amygdala, paraventricular nucleus (PVN), and cingulate cortex (Cg) was shown by a two-proportion Z-test (p = 1.6 x 10^-31), with a positive correlation in the CeA (p = 0.0062), PVN (p = 0.0046) and Cg (p = 0.0114), indicating a contribution of CNVs to the genetic predisposition to trait anxiety in the specific context of HAB/LAB mice. In order to confirm anxiety-relevant CNVs and corresponding genes in a second mouse model, we further examined CD-1 outbred mice. We revealed the distribution of CNVs by genotyping 64 CD 1 individuals using a high-density genotyping array (Jackson Laboratory). 78 genes within those CNVs were identified to show nominally significant association (48 genes), or a statistical trend in their association (30 genes) with the time animals spent on the open arms of the elevated plus-maze (EPM). Fifteen of them were considered promising candidate genes of anxiety-related behavior as we could show a significant overlap (permutation test, p = 0.0051) with genes within HAB/LAB CNVs. Thus, here we provide what is to our knowledge the first extensive catalogue of CNVs in CD-1 mice and potential corresponding candidate genes linked to anxiety-related behavior in mice.     

Role of learning of open arm avoidance in the phenomenon of one-trial tolerance to the anxiolytic effect of chlordiazepoxide in mice

A single exposure to the elevated plus-maze (EPM) test of anxiety reduces or abolishes the anxiolytic efficacy of benzodiazepines on a second trial. Some possible explanations to the occurrence of this phenomenon (one-trial tolerance-OTT) involve behavioral modifications thought to be consequence of some kind of learning in the first trial. In the present study, the influence of learning-impairing situations on the effects of the benzodiazepine chlordiazepoxide on mice re-tested in the EPM is investigated. The results showed that: (1) as expected, the administration of chlordiazepoxide to mice re-tested in the EPM- under the same conditions of the first trial- failed to induce anxiolysis; (2) a decreased percent time in the open arms was observed on the second trial of mice exposed to both trials under the same experimental conditions; (3) neither the increase in open arm avoidance by mice re-exposed to the EPM nor the OTT to chlordiazepoxide effect were modified by administration of the amnestic agent scopolamine; (4) the decrement of the duration of the first trial to 1 min or the change in light and noise conditions in both trials counteracted the increase in open arm avoidance on trial 2; (5) none of the later procedures modified the phenomenon of OTT. Although not discarding the modulation exerted by other memory processes in the OTT phenomenon, the results indicate that situations that impair the learned avoidance response to the open arms in the EPM do not modify the phenomenon of OTT.