中文摘要：

目的观察血管性痴呆（vD）模型大鼠海马齿状回（DG）区的超微结构变化，并探讨其与空间学习记忆功能的关系。方法成年雄性SD大鼠12只按随机数字表法分为假手术组（n=6）与VD模型组（n=6），VD模型组采用改良的双侧颈总动脉永久性结扎法制备VD模型，假手术组除了不结扎双侧颈总动脉外其余步骤均与VD模型组相同。利用Morris水迷宫评估2组大鼠学习记忆能力，并用透射电镜观察2组大鼠海马DG区的超微结构。结果（1）在4d的Morris水迷宫定位航行实验中，VD模型组大鼠的逃避潜伏期明显长于假手术组．差异有统计学意义（P〈0．05）；而在第5天的空间探索实验中，VD大鼠穿越原站台象限的次数明显少于假手术组。差异有统计学意义（P〈0．05）。（2）VD模型组大鼠海马DG区的超微结构出现明显异常，包括突触小泡数量减少，粗面内质网数量减少、排列紊乱，游离核糖体增多，线粒体双层膜和嵴结构模糊不清、嵴断裂并变短减少，突触间隙模糊不清等。结论VD模型大鼠出现空间学习记忆的损害可能与海马DG区超微结构的损伤有关。

英文摘要：

Objective To observe the ultrastructure changes ofhippocampal dentage gyrus （DG） and spatial learning and memory ability changes in rats models of vascular dementia （VD）, and investigate the relationship between them. Methods Twelve adult male SD rats were randomly divided into sham-operated group and VD model group （n=6）; the VD rat models were prepared by improved permanent bilateral carotid occlusion. The spatial learning and memory abilities of rats were assessed by Morris water maze （MWM）, and the ultrastructures of DG were detected by transmission electron microscope. Results （1） In the place navigation trial of MWM, the mean escape latency in VD group was significantly longer than that in sham-operated group （P〈0.05）; in the spatial probe trial, the number of platform crossings in VD group was markedly smaller as compared with that in sham-operated group （P〈0.05）. （2） The changes in ultrastructures of hippocampal DG in VD rats were as follows： the number of synaptic vesicles was reduced; the rough endoplasmic reticulum was reduced and arranged in disorder, and free ribosome was increased; the membrane and cristae of mitochondria in the synaptosoma were blurred, and the cristae was fractured; the synaptic cleft was blurred. Conclusion The spatial learning and memory disabilities in VD rats may be associated with injury of ultrastructures in hippocampal DG.