IDO、KYN在大鼠慢性脑低灌注所致认知障碍中的作用

发布时间：2018-07-30 07:53

【摘要】：目的：在我国，血管性认知障碍（vascular cognitive impairment,VCI）是老年期痴呆的主要组成部分，不仅会严重损害患者的健康及生存质量，也给社会和家庭带来了沉重负担。目前，VCI的发病机制尚不十分清楚，也无特殊有效的治疗方法，因此探讨VCI的发病机理，制定合理的治疗方案，是医学领域研究中的重要课题。慢性脑低灌注是VCI、阿尔茨海默病(Alzheimer's Disease,AD)等多种神经系统疾病发生发展过程中的一个共同病理过程。慢性脑供血不足发病早期以轻度认知障碍为主要表现，最终可导致持久或进展性的认知与神经功能障碍。有研究指出，犬尿氨酸通路相关代谢产物可以引起神经系统损害，可能是产生脑实质和脑微血管系统损害的重要物质，故我将通过检测吲哚胺-2,3-双加氧酶(indoleamine2,3-dioxygenase,IDO)、犬尿氨酸(kynurenine,Kyn)等相关因子，探讨犬尿氨酸通路相关代谢产物在慢性脑低灌注所致认知障碍的作用。方法：用健康雄性Wistar大鼠30只，鼠龄3~4个月，体质量200～250g，随机分成实验组（n=15），假手术对照组（n=15）。实验组大鼠行改良的双侧颈总动脉结扎术,假手术组大鼠除不结扎双侧颈总动脉外,余处理同实验组。各组大鼠术后4周在水迷宫测试后断头，在冰上快速取海马组织。行免疫组化染色观察海马病理变化和海马IFN-γ、TNF-a、iNOS表达变化。行ELISA法显示IDO、KYN含量变化。运用SPSS17.0统计软件进行比较，，P0.05表示有统计学意义。结果：（1）两组大鼠存活情况：实验组大鼠死亡2只，死亡率为13.3%；假手术组大鼠全部存活。（2）水迷宫试验：实验组大鼠学习、记忆成绩显著下降，表现为逃避潜伏期延长，平台象限游泳距离百分比减少，明显高于假手术组（P0.05）。(3)免疫组织化学方法显示海马CA1区IFN-γ、TNF-a、iNOS表达变化：假手术组海马CA1区仅见极少量阳性神经元；实验组可见大量阳性神经元，且排列松散，胞体变小，核固缩，阳性细胞累计光密度（IOD）值高于假手术组(P0.05)。（4）ELISA法提示，实验组大鼠海马IDO及KYN浓度多于对照组(P0.05)。结论：(1)通过水迷宫证实了慢性脑低灌注大鼠存在学习和记忆功能障碍。(2)采用免疫组织化学方法，证实了在慢性脑低灌注状态下大鼠海马组织IFN-γ、TNF-a表达增加，说明慢性脑低灌注大鼠的病理生理过程包含着炎性反应，而炎性反应的发生很可能刺激了IDO的高表达。(3)实验组海马IDO、KYN含量显著增加，提示在慢性脑低灌注中伴随着KYN、IDO的蓄积，从而有可能引起脑损伤，参与慢性脑低灌注致认知障碍的过程。
[Abstract]:Objective: vascular cognitive impairment (vascular cognitive) is a major component of senile dementia in China, which not only seriously damages the health and quality of life of patients, but also brings a heavy burden to society and family. At present, the pathogenesis of VCI is not very clear, and there is no special and effective treatment method. Therefore, it is an important subject in the field of medicine to explore the pathogenesis of VCI and formulate a reasonable treatment scheme. Chronic cerebral hypoperfusion is a common pathological process in the occurrence and development of many nervous system diseases such as VCI, Alzheimer's disease (AD) and so on. Mild cognitive impairment is the main manifestation in the early stage of chronic cerebral blood supply insufficiency, which can eventually lead to persistent or progressive cognitive and neurological dysfunction. Studies have shown that the metabolites associated with the canine uric acid pathway can cause damage to the nervous system and may be important substances that cause damage to the brain parenchyma and the brain microvascular system. Therefore, we will investigate the role of the metabolites of canine uremic acid pathway in cognitive impairment induced by chronic cerebral hypoperfusion by detecting indoleamine-3-dioxygenase (IDO) and kynurenine (kynurenine kyn) and other related factors. Methods: 30 healthy male Wistar rats, aged 3 ~ 4 months, were randomly divided into experimental group (n = 15) and sham operation control group (n = 15). Rats in the experimental group were treated with modified bilateral common carotid artery ligation, and the sham-operated rats were treated the same as the experimental group except the bilateral common carotid artery was not ligated. Four weeks after operation, the rats were severed after water maze test, and hippocampal tissue was quickly removed from the ice. The pathological changes of hippocampus and the expression of IFN- 纬 -TNF-aF- iNOS in hippocampus were observed by immunohistochemical staining. ELISA method was used to show the change of IDOKYN content. The use of SPSS17.0 statistical software to compare P05 indicated that there was statistical significance. Results: (1) the survival of rats in the two groups: two rats died in the experimental group, the mortality was 13.3%, and all the rats in the sham operation group survived. (2) the water maze test showed that the rats in the experimental group were learning, the memory scores were significantly decreased, and the escape latency was prolonged. The percentage of swimming distance in platform quadrant decreased, which was significantly higher than that in sham-operated group (P0.05). (3). The expression of IFN- 纬 -TNF-afi-iNOS in hippocampal CA1 area was significantly higher than that in sham-operated group (P0.05). (3). Only a few positive neurons were found in CA1 area of hippocampus in sham operation group, and a large number of positive neurons were found in experimental group. The (IOD) value of the positive cells was higher than that of the sham-operated group (P0.05). (4) ELISA method. The concentration of IDO and KYN in the hippocampus of the experimental group was higher than that of the control group (P0.05). Conclusion: (1) Learning and memory dysfunction in rats with chronic cerebral hypoperfusion was confirmed by water maze. (2) the expression of IFN- 纬 -TNF-a in hippocampus of chronic cerebral hypoperfusion rats was confirmed by immunohistochemical method. It was suggested that the pathophysiological process of chronic cerebral hypoperfusion rats included inflammatory response, and the occurrence of inflammatory reaction probably stimulated the high expression of IDO. (3) the content of IDOKYN in hippocampus of experimental group increased significantly, which suggested that the accumulation of KYN IDO was associated with chronic cerebral hypoperfusion. This may lead to brain injury and participate in the process of cognitive impairment caused by chronic cerebral hypoperfusion.
【学位授予单位】：山西医科大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R749.16

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