【作者】 杨林；

【导师】 王红阳；

【作者基本信息】 华北煤炭医学院 ， 内科学， 2010， 硕士

【摘要】 目的:通过模拟OSAHS的发病特征,建立大鼠间歇性低氧(IH)模型,观察5%间歇低氧条件下,不同暴露时间过程对大鼠的学习记忆功能的影响和海马CA1区超微结构的改变,为研究OSAHS引起的认知功能损害提供实验基础。方法:选择成年雄性Wistar大鼠(体重约170±10g)48只,随机均分为2组:空白对照组(UC组)和5%间歇性低氧组(5%IH组),UC组放入舱内给予压缩空气,IH组大鼠每日放入自制的低氧舱内暴露8小时,分别暴露2、4、6、8周。各组大鼠均常规饲养。在实验结束后进行Morris水迷宫实验;利用光镜和电镜观察海马组织结构和超微结构的变化。结果:1、Morris水迷宫测试成绩:①定位航行实验:各组大鼠的逃避潜伏期均随实验天数延长而逐渐缩短,不同天数之间比较,逃避潜伏期有明显差异(P<0.05)。IH各组逃避潜伏期随着缺氧时间延长呈逐渐延长趋势。不同暴露组之间及与对照组的逃避潜伏期比较不完全相同。5%IH2周组与6周、8周组比较,4周组与8周组比较差异显著(P<0.05),其它各组内比较无差异明显(P>0.05)。②Morris水迷宫记忆成绩:⒈跨越目标象限时间:各CIH组随着低氧时间延长和低氧浓度的降低,跨越目标象限时间呈逐渐缩短趋势。IH组与UC组之间比较有显著差别(P<0.05)。5%CIH2周组和4、6、8周组比较差异显著(P<0.05);⒉穿台次数:采用非参数检验(秩和检验),不同暴露条件之间以及不同暴露时间之间不完全相同,随着间歇低氧浓度的降低,穿台次数减少,P<0.01。2、光镜下海马组织结构的变化随着间歇低氧时间的延长,早期表现为核固缩呈强嗜碱性,核染色质聚集在核膜下呈环状,晚期凋亡表现为核溶解碎裂等,尼氏体结构逐渐变模糊并发生崩解。随着暴露时间的延长神经元数量减少。亦可见肿胀神经元细胞,表现为细胞空泡化,透亮度增高,胞浆成分不明显。3、电镜观察可见正常海马神经元核核大而圆,核仁清晰,核质均匀散在,核膜光滑,边缘清晰,细胞器丰富完整。间歇低氧组随着暴露时间的延长,海马神经元早期表现为细胞核形态变化不明显,糖原颗粒减少。后期出现核沟,并逐渐加深加大,染色质边集。细胞器逐渐减少,线粒体空泡化并出现异型结构,粗面内质网表面的脱颗粒现象逐渐加重。神经元数量减少。突触结构随暴露时间逐渐出现突触小泡增大,结构模糊,突触间隙增宽。暴露至6周时脱髓鞘现象达高峰。各时间段血管均有不同程度的水肿。结论:1、间歇性低氧可造成大鼠学习记忆功能的降低。随着暴露时间的延长,大鼠学习记忆功能损害呈现逐渐加重趋势,慢性间歇性低氧在暴露一定时间后出现明显的学习记忆功能障碍。2、间歇性低氧可引起海马神经元的损害,随着暴露时间的延长而逐渐加重。更多还原

【Abstract】 ObjectiveWe set up an intermittent hypoxia animal model by simulating the features of OSAHS(obstructive sleep apnea-hypopnea syndrome) to observe the learning and memory changes and the ultrastructure in CA1 region of the hippocampus exposed to 5%IH.Our purpose is that providing a theoretical basis of cognitive impairment for OSAHS patients.MethodsExperiments were performed on 48 mature male Wistar rats,they were randomly assigned to three experimental groups(n=6/group weight 170±10g):5% intermittent hypoxia group(5%IH) and unhandled control group (UC). Rats in every group were raised normally, and then those in IH groups suffered 8 hours intermittent hypoxia everyday, the duration of experiment was respectively 2,4,6 and 8 weeks. The compressed air was given to the UC group. The learning and memory ability of rats in each group were assessed with the Morris water maze(MWM) test at the end of the experiments,and then we observed the ultramicrostructural changes in the hippocampus of rats with electromicroscope and light microscope.Results1、Morris water maze test learning scores:①place navigation:The escape latency period was shorted gradually during the place navigation in all groups and there were signifcant statistically differences among different days(P<0.05).There were trends that the escape latency period of IH groups prolonged with hypoxia time increased. The escape latency period was apparently different between 5% IH and UC groups. Within-subjects contrasts: The escape latency period in 5%IH2w was shorter than5%IH6w,8w groups.The ELP in 5%IH8w was much longer than that in 5%IH4w(P<0.05).The contrast had not sharply differences among other IH groups.②spatial probe :⒈frequency of crossing the platform : Using nonparametric tests, the number of times of crossing the platform in different exposure time were not incompletely same.With the prolongation of exposure time, the numbers of crossing the platform decreased( P<0.01).⒉crossing the target quardant time:The time spent on crossing the target quardant to the total swimming time had gradually degressive trends with the extension of hypoxia time in IH groups.There was notable distinction between IH groups and UC group(P<0.05). 5%IH2w group was different with 5%IH4w,6w,8w groups.2、the change of hippocampus structure under the light microscopeWith the extention of intermittent hypoxia, each stage apoptosis could be seen in neuron cells.The phenomenon was observed that nuclear chromatin buildup under the nuclear envelope at the nonage.Nuclear fragmentation were observed at advanced stage. Tigroid body became blur gradually and generated dosaggregation. The quantity of neuron diminished along with the extention of intermittent hypoxia. Besides we also observed oncootic neurons which showed vacuolization and the raise of lucency ,but the composition of kytoplasm did not clear.3、We could observe that chromatospherite is clear, caryoplasm displayed uniform distribution caryotheca was smooth and glossy, and cell organ was abundant and integrated. With the extention of exposure time,hippocampus neurons displayed that the reduction of glycogen granule and lower-grade damage in intermittent hypoxia groups.The fissura of cellular nucelus emerged and became deeply with the extention of exposure time. The quantity of cell organ diminished, apart from this chondrosome showed vacuolization and emerged allotype. The phenomenon of degranulation in the surface of Rough endoplasmic reticulum became serious. With the extention of exposure time, synaptic vesicle greaten,Frame became indefinite and synaptic cleft widen.The following appearance,including chromatin margination and the formation of the decrease of neuron, happened at the later stage. Demyelinate reached the peak when the rats exposured to six weeks.Blood vessel showed different degree oedema at each stage.Conclusion1、Chronic intermittent hypoxia can make the function of learning and memory in rats drop. With the extention of exposure time , the function of learning and memory presents the gradually aggravating trend. The rats have presented obvious cognitive impairment when the chronic intermittent hypoxia reaches certain time.2、The injury of hippocampus neurons could be resulted in by chronic intermittent hypoxia. With the extention of exposure time , the injury of hippocampus neurons became serious.更多还原