金刚烷胺减缓抑郁模型大鼠认知功能的损伤及其机理研究

发布时间：2019-01-10 12:51

【摘要】：抑郁症(depression)是一种由多种原因引起的心境障碍或情感障碍,以显著而持久的心境低落为主要临床特征,患者常常伴有明显的认知功能障碍,包括执行功能障碍、记忆障碍、注意障碍等。抑郁症的发病机制复杂,如有研究报道在生活中遭遇过度的挫折和刺激会引发抑郁。据此,在基础临床研究中,常常将各种不同的应激刺激施加于动物身上来模拟抑郁的发展并研究其发病机制及治疗。其中,慢性不可预知性应激模型(chronic unpredictable stress, CUS)是目前应用较广泛且获得学术界普遍认可的抑郁症动物模型之一。它主要模拟了抑郁的核心表现,即快感缺乏。研究发现慢性不可预知性应激模型大鼠的空间学习及灵活性显著下降。在慢性应激的刺激下,海马CA3区神经元萎缩、树突棘形态严重受损、齿状回区神经元的再生减少,且其突触可塑性也受到了严重的损伤,这些改变与其导致的认知功能损伤密切相关。金刚烷胺(amantadine, AMA)是一种三环癸烷氨基衍生物。最早它主要用于流行性感冒的治疗和预防,后来发现其具有治疗帕金森氏综合症的作用。其可能的机制是由于它能促进纹状体内多巴胺能神经末梢释放多巴胺(dopamine,DA)。此外,它还能通过绑定N-甲基-D-天冬氨酸受体(N-methyl-D-aspartic acid, NMDA)和阻断谷氨酸进入细胞起到对神经元的保护作用。与美金刚(memantine,MEM)一样,它是一种低中度亲和力、非竞争性的NMDA受体拮抗剂。实验室的前期研究发现,美金刚能改善抑郁模型大鼠的抑郁样症状,并对抑郁模型大鼠水迷宫反向学习的损伤具有恢复倾向,并指出其可能是通过调节NR2B受体,部分恢复了应激大鼠受损的突触可塑性。金刚烷胺作为临床应用的药品,与美金刚结构相似,但是其价格低廉、副作用明确,耐受性好,使用历史也较长。因此在本研究中,将主要探讨金刚烷胺是否具有减缓抑郁模型大鼠的认知功能损伤,及其可能的细胞学和分子生物学机制。本实验选用雄性Wistar大鼠,随机分成四组：对照组(CON)、AMA对照给药组(CON+AMA)、应激模型组(STRESS)、AMA模型给药组(STRESS+AMA)。应激模型组采用CUS模型,并结合孤独饲养,以此来模拟抑郁样的行为表现,用糖水偏好实验及体重变化来验证建模是否成功。水迷宫实验主要检测动物空间记忆功能及再认知的灵活性。应用电生理技术记录海马Schaffer侧枝到CA1的长时程增强(long term potentiation, LTP)和去增益(depotentiation, DP)。应用Western blot技术检测海马中NMDA受体的功能亚单位NR2B及突触后致密蛋白95 (postsynapticdensity-95, PSD-95)的相对表达量,以此来了解金刚烷胺对抑郁样模型大鼠空间认知功能受损的可能疗效,并探讨其潜在的机制。主要实验结果如下：(1) STRESS组大鼠体重增长及糖水消耗百分比显著低于正常对照组,而金刚烷胺明显增加了应激模型组大鼠体重增长缓慢的趋势,并提高了其糖水消耗百分比。(2)在定位航行阶段,与正常对照组相比,STRESS组大鼠的逃避潜伏期明显延长,而金刚烷胺显著缩短了STRESS组大鼠的逃避潜伏期。并在空间探测阶段,应激模型组大鼠的目标象限停留时间百分比和平台穿越次数显著减少,而AMA给药后明显增加。(3)在空间反向训练阶段,STRESS组大鼠需要更多的时间找到平台所在的新位置,而给予金刚烷胺则显著地减少了应激大鼠的逃避潜伏期。此外,新目标象限停留时间百分比和平台穿越次数在STRESS组大鼠中较CON组大鼠明显减少,AMA显著增加了平台穿越次数,新目标象限目标百分比有所增加但无统计学差异。(4)与对照组相比,STRESS组大鼠海马CA1区的LTP显著降低而去增益明显增加,给予金刚烷胺之后LTP显著增加且去增益明显降低。(5) Western blot实验结果显示STRESS组大鼠海马中NR2B及PSD-95的相对表达量明显低于CON组和STRESS+AMA组。根据以上的结果,我们得到如下结论：(1)金刚烷胺能有效的减缓应激模型大鼠快感缺乏、体重减轻等症状,表现出潜在的抗抑郁效果。(2)金刚烷胺能降低抑郁模型大鼠的认知功能损伤程度,其潜在的机制可能是增加了海马中NR2B和PSD-95的相对表达量,从而阻止了CA3-CA1的LTP和去增益的双向可塑性失衡,进而减缓了抑郁模型大鼠的空间认知损伤。
[Abstract]:Depression is a kind of mood disorder or affective disorder, which is caused by a variety of reasons, which is characterized by a significant and persistent state of mind and is often accompanied by obvious cognitive impairment, including executive dysfunction, memory disorder, attention disorder, and the like. The pathogenesis of depression is complex, as it is reported that excessive setbacks and irritation in life can trigger depression. Therefore, in the basic clinical study, various stress stimulation is often applied to the animal to simulate the development of the depression and to study the pathogenesis and treatment of the depression. The chronic unpredictable stress model (CUS) is one of the most widely accepted models of depression in the academic community. It mainly simulates the core performance of depression, that is, the lack of pleasure. The study found that there was a significant decrease in the spatial learning and the flexibility of the rats with chronic unpredictable stress model. Under the stimulation of chronic stress, the neurons of the CA3 region of the hippocampus atrophy, the shape of the dendritic spine is severely damaged, the regeneration of the dentate gyrus neurons is reduced, and the synaptic plasticity of the dentate gyrus is also severely damaged, and the changes are closely related to the cognitive function damage caused by the changes. amantadine (AMA) is a tricyclic decane amino derivative. It was the first to be used for the treatment and prevention of influenza, and it was later found to have the effect of treating Parkinson's disease. The possible mechanism is that it promotes dopamine in the striatum to release dopamine (DA). In addition, it can play a protective role on neurons by binding the N-methyl-D-aspartate receptor (N-methyl-D-aspartic acid, NMDA) and blocking glutamate. Like memantine (MEM), it is a low medium affinity, non-competitive NMDA receptor antagonist. The early study of the laboratory found that memantine can improve the depression-like symptoms in the depressed model rats and have a tendency to recover the damage to the water maze of the depressed model rats, and point out that it may be through the regulation of the NR2B receptor, and the partial recovery of the stress-induced synaptic plasticity in the stress rats. As a medicine for clinical application, the amantadine is similar to that of the memantine structure, but has the advantages of low price, clear side effect, good tolerance and long use history. Therefore, in this study, it will be mainly discussed whether the amantadine has the cognitive function damage of the depression model rats, and the possible mechanism of cytology and molecular biology. Male Wistar rats were randomly divided into four groups: control group (CON), AMA control group (CON + AMA), stress model group (STRESS) and AMA model group (STRESS + AMA). In the stress model group, the CUS model was used to simulate the behavior of the depression, and the experiment and weight change of the sugar water were used to verify the success of the model. The experiment of water maze mainly detects the memory function of the animal and the flexibility of the re-cognition. The long term potentiation (LTP) and de-gain (DP) of the hippocampal Schaffer side branch to CA1 were recorded by electrophysiology. The relative expression of the functional subunit NR2B and postsynaptic compact protein 95 (PSD-95) of the NMDA receptor in the hippocampus was detected by Western blot. The results of the main experiments were as follows: (1) The weight gain and the percentage of sugar water consumption in the STRESS group were significantly lower than that of the control group, and the amantadine significantly increased the weight gain of the rats in the stress model group and increased the percentage of sugar water consumption. (2) Compared with the normal control group, the escape latency of the STRESS group was significantly prolonged compared with the normal control group, and the amantadine significantly shortened the escape latency of the STRESS group rats. At the stage of spatial detection, the percentage of the target quadrant retention time and the number of platform-crossing times in the stress model group were significantly reduced, and the AMA was significantly increased after administration. (3) In the stage of space reverse training, the STRESS rats need more time to find the new position of the platform, and the amantadine significantly reduces the escape latency of the stress rats. in addition, that percentage of residence time of the new target quadrant and the number of platform traverse decreased significantly in the CON group in the STRESS group, and AMA significantly increased the number of platform crossing, and the target percentage of the new target quadrant increased without statistical difference. (4) Compared with the control group, the LTP in the CA1 region of the rats in the STRESS group was significantly reduced and the gain was significantly increased, and the LTP was significantly increased after the amantadine was given and the degain was significantly reduced. (5) The results of Western blot showed that the relative expression of NR2B and PSD-95 in the hippocampus of the rats was significantly lower than that of the CON group and the STRESS + AMA group. Based on the above results, we have the following conclusion: (1) The amantadine can effectively slow down the symptoms of the stress model, such as the lack of the pleasure, the weight loss, and the like, and show the potential antidepressant effect. (2) The potential mechanism of amantadine to decrease the degree of cognitive function injury in the depressed model rats may be to increase the relative expression of NR2B and PSD-95 in the hippocampus, thus preventing the two-way plastic imbalance of the LTP and de-gain of CA3-CA1, so that the spatial cognitive impairment of the depression model rats is reduced.
【学位授予单位】：南开大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：R749.4

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