慢性复合应激对学习记忆功能的影响及神经颗粒素在其机制中的作用
发布时间：2019-06-18 11:51
【摘要】： 应激是机体在内外环境剧变的刺激下所产生的综合应答状态,包括精神、神经、内分泌和免疫等方面的反应。当机体接受某种应激原刺激时,其下丘脑-垂体-肾上腺(Hypothalamus-pituitary-adrenal gland,HPA)轴的兴奋性增强,肾上腺分泌应激激素,使血液中糖皮质激素(GC)水平升高,最终产生一系列的非特异性适应反应。应激对机体的影响取决于应激模式、应激强度和持续时间以及机体的反应性等因素。其中,应激对认知功能的影响更为复杂。目前,大多数研究结果显示慢性应激损伤动物的学习和记忆功能,但也有少数实验结果表明慢性应激可增强动物的学习和记忆功能。 中枢神经系统的海马脑区富含糖皮质激素受体(GR),是中枢GR含量最高的脑区,因而是HPA轴应激反应的高位调节中枢和应激激素的主要靶区。而且,由于海马的解剖位置和它与多个脑区之间的纤维联系,使得海马成为学习与记忆的重要脑区。神经颗粒素(Neurogranin,Ng)是一种78个氨基酸组成的神经元特异性蛋白,主要分布于大脑皮层、海马和嗅球等脑区。作为Calpacitin蛋白家族中的一员,它不仅是蛋白激酶C(Protein kinase C, PKC)的天然作用底物,还是突触后钙调蛋白(CaM)结合蛋白。在生理状态下,Ng与CaM结合成CaM-Ng复合体,而当Ng被PKC磷酸化或被氧化剂氧化或细胞内的Ca2+浓度升高时,Ng与CaM的亲和力下降,CaM-Ng复合体解离,释放出游离的CaM,从而实现对CaM及Ca2+/CaM依赖性蛋白激酶和蛋白酶等活性的调节。同时,这些酶大多参与长时程增强(LTP)的诱导。LTP是突触传递效能持续增强的一种表现形式,是突触可塑性的一个重要功能性指标,而突触可塑性则是中枢神经系统可塑性这一学习和记忆的重要机制的基础。因此,Ng可能在学习和记忆的神经系统可塑性等生理性变化中具有重要作用。 本实验采用4种应激原组成的复合应激,将应激时间持续6周,以模拟现代社会人类面临的复杂的生存环境,如竞争、经济、人际关系等所产生的慢性社会心理应激,处理实验动物,制作动物模型,探讨慢性复合应激对动物学习与记忆功能的影响和Ng在此影响机制中的作用。实验将成年雄性Wistar大鼠随机分为2组:(1)对照组:平行接受常规喂养,不作任何处理;(2)慢性复合应激组:每天无规律交替暴露于水池中睡眠剥夺、金属网笼中捆绑、垂直旋转器垂直旋转、和夜间间歇性光照4种应激原组成的复合应激环境中,持续6周。观察慢性复合应激对大鼠体重和行为的影响;应激结束后,用Morris水迷宫测试大鼠的空间学习与记忆成绩;采用免疫组织化学方法观察大鼠海马各亚区Ng表达水平的变化;同时应用RT-PCR技术分析各组大鼠海马Ng mRNA水平的变化。结果显示: 1、慢性复合应激组动物警惕性增高,呈现攻击性增强的趋势,且排泄物增多; 2、慢性复合应激组大鼠的体重增长幅度明显小于对照组(p0.05); 3、Morris水迷宫测试提示,应激前两组大鼠寻找隐蔽平台的潜伏期无明显差别,应激后慢性复合应激组大鼠的空间学习记忆能力(潜伏期:14.19s)明显好于对照组(潜伏期:18.89s)(p0.05); 4、分析免疫组织化学实验结果,海马DG区和CA3区Ng的蛋白表达水平明显高于对照组(p0.05),而两组海马CA1区的Ng的免疫反应性无显著差别; 5、与对照组相比,慢性复合应激组动物的Ng mRNA水平亦明显上调。实验结果提示,慢性复合应激可增强海马依赖的学习与记忆功能,而Ng蛋白在海马中的表达和Ng mRNA转录水平的增高,则说明Ng参与了该增强机制。
[Abstract]:Stress is the comprehensive response state of the body under the stimulation of the change of the internal and external environment, including the reaction of the spirit, the nerve, the endocrine and the immunity. The hypothalamic-pituitary-adrenal gland (HPA) of the hypothalamus-pituitary-adrenal gland (HPA) of the body increases the excitability of the shaft of the hypothalamus-pituitary-adrenal gland (HPA), and the adrenal gland secretes the stress hormone to increase the level of the glucocorticoid (GC) in the blood, resulting in a series of non-specific adaptation reactions. The effect of stress on the body depends on the stress pattern, the stress intensity and the duration, and the reactivity of the body. The effect of stress on cognitive function is more complicated. At present, most of the results show that the learning and memory function of the animals with chronic stress damage, but a few experimental results show that the chronic stress can enhance the learning and memory function of the animals. The brain region of the central nervous system is rich in the glucocorticoid receptor (GR), which is the brain region with the highest central GR content, and is thus the high-level regulation center and the stress-induced stress response of the HPA axis stress reaction. In addition, due to the anatomical location of the hippocampus and the fiber connection between it and a plurality of brain regions, the hippocampus becomes a learning and a memory. Neurogranin (Ng) is a neuron-specific protein composed of 78 amino acids, which is mainly distributed in the cerebral cortex and the hippocampus. As a member of the family of Calpacitin, it is not only a natural active substrate of protein kinase C (PKC), or postsynaptic calmodulin (Ca M) Binding protein. In physiological state, Ng and CaM are combined into CaM-Ng complex, and when Ng is phosphorylated by PKC or oxidized by the oxidizing agent or the concentration of Ca 2 + in the cell increases, the affinity of Ng and CaM decreases, and the CaM-Ng complex is dissociated and released. Free CaM for CaM and Ca2 +/ CaM-dependent protein kinases and proteases At the same time, most of these enzymes are involved in long-term potentiation (L The induction of TP is an expression of the continuous enhancement of synaptic transmission, which is an important functional index of the synaptic plasticity, and the plasticity of the synapse is the core of the study and memory of the plasticity of the central nervous system. The foundation of the mechanism. Therefore, Ng may be in physiological changes, such as learning and memory neuroplasticity. The invention has the important effect. The experiment adopts four stress original compound stress, and the stress time is continued for 6 weeks, so as to simulate the complex living environment of the modern society human, such as the chronic social psychological stress caused by the competition, the economy, the human relationship and the like, To study the effect of chronic compound stress on the learning and memory function of animals and (2) the chronic composite stress group: the daily irregular exposure to the sleep deprivation in the pool, the metal mesh cage, The vertical rotation of the vertical rotator and the intermittent illumination at night are composed of four stress sources. The effects of chronic compound stress on body weight and behavior of rats were observed in a complex stress environment. After the stress, the space and memory of the rats were tested by Morris water maze. Changes of the expression level of Ng in each subzone of the horse, and the simultaneous application of RT-PCR to the analysis of each group of rats Hippocampus Ng m The change of RNA level. The results showed that:1. The vigilance of the animals in the chronic compound stress group to increase, to present a trend of aggression enhancement, and to increase the amount of excretion;2. Chronic complex The weight gain of the rats in the combined stress group was obviously small. In the control group (p0.05),3, Morris water maze test suggested that there was no significant difference in the latency of the two groups of rats before the stress, and the spatial learning and memory ability of the rats after the stress (incubation period) : 14.19 s) was better than the control group (incubation period: 18.89 s) (p0.05);4. Analysis of the results of the immunohistochemical study, the protein tables of the hippocampal DG region and the CA3 region Ng. The level of Ng in the CA1 region of the two groups was significantly higher than that in the control group (p0.05). There was no significant difference in reactivity.5. The level of Ng mRNA in the chronic compound stress group was also up-regulated in comparison with the control group. The results suggested that the chronic compound stress could enhance the dependence of the hippocampus.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2006
【分类号】：R33
本文编号：2501466
[Abstract]:Stress is the comprehensive response state of the body under the stimulation of the change of the internal and external environment, including the reaction of the spirit, the nerve, the endocrine and the immunity. The hypothalamic-pituitary-adrenal gland (HPA) of the hypothalamus-pituitary-adrenal gland (HPA) of the body increases the excitability of the shaft of the hypothalamus-pituitary-adrenal gland (HPA), and the adrenal gland secretes the stress hormone to increase the level of the glucocorticoid (GC) in the blood, resulting in a series of non-specific adaptation reactions. The effect of stress on the body depends on the stress pattern, the stress intensity and the duration, and the reactivity of the body. The effect of stress on cognitive function is more complicated. At present, most of the results show that the learning and memory function of the animals with chronic stress damage, but a few experimental results show that the chronic stress can enhance the learning and memory function of the animals. The brain region of the central nervous system is rich in the glucocorticoid receptor (GR), which is the brain region with the highest central GR content, and is thus the high-level regulation center and the stress-induced stress response of the HPA axis stress reaction. In addition, due to the anatomical location of the hippocampus and the fiber connection between it and a plurality of brain regions, the hippocampus becomes a learning and a memory. Neurogranin (Ng) is a neuron-specific protein composed of 78 amino acids, which is mainly distributed in the cerebral cortex and the hippocampus. As a member of the family of Calpacitin, it is not only a natural active substrate of protein kinase C (PKC), or postsynaptic calmodulin (Ca M) Binding protein. In physiological state, Ng and CaM are combined into CaM-Ng complex, and when Ng is phosphorylated by PKC or oxidized by the oxidizing agent or the concentration of Ca 2 + in the cell increases, the affinity of Ng and CaM decreases, and the CaM-Ng complex is dissociated and released. Free CaM for CaM and Ca2 +/ CaM-dependent protein kinases and proteases At the same time, most of these enzymes are involved in long-term potentiation (L The induction of TP is an expression of the continuous enhancement of synaptic transmission, which is an important functional index of the synaptic plasticity, and the plasticity of the synapse is the core of the study and memory of the plasticity of the central nervous system. The foundation of the mechanism. Therefore, Ng may be in physiological changes, such as learning and memory neuroplasticity. The invention has the important effect. The experiment adopts four stress original compound stress, and the stress time is continued for 6 weeks, so as to simulate the complex living environment of the modern society human, such as the chronic social psychological stress caused by the competition, the economy, the human relationship and the like, To study the effect of chronic compound stress on the learning and memory function of animals and (2) the chronic composite stress group: the daily irregular exposure to the sleep deprivation in the pool, the metal mesh cage, The vertical rotation of the vertical rotator and the intermittent illumination at night are composed of four stress sources. The effects of chronic compound stress on body weight and behavior of rats were observed in a complex stress environment. After the stress, the space and memory of the rats were tested by Morris water maze. Changes of the expression level of Ng in each subzone of the horse, and the simultaneous application of RT-PCR to the analysis of each group of rats Hippocampus Ng m The change of RNA level. The results showed that:1. The vigilance of the animals in the chronic compound stress group to increase, to present a trend of aggression enhancement, and to increase the amount of excretion;2. Chronic complex The weight gain of the rats in the combined stress group was obviously small. In the control group (p0.05),3, Morris water maze test suggested that there was no significant difference in the latency of the two groups of rats before the stress, and the spatial learning and memory ability of the rats after the stress (incubation period) : 14.19 s) was better than the control group (incubation period: 18.89 s) (p0.05);4. Analysis of the results of the immunohistochemical study, the protein tables of the hippocampal DG region and the CA3 region Ng. The level of Ng in the CA1 region of the two groups was significantly higher than that in the control group (p0.05). There was no significant difference in reactivity.5. The level of Ng mRNA in the chronic compound stress group was also up-regulated in comparison with the control group. The results suggested that the chronic compound stress could enhance the dependence of the hippocampus.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2006
【分类号】：R33
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