中文摘要：

目的为研究脑老化过程中学习、记忆功能减退的神经结构基础提供实验依据。方法应用透射电子显微镜,观察比较从出生1 d至24月龄（1 d、1月龄、3月龄、6月龄、18月龄、24月龄）的Sprague Dawley大鼠海马神经元突触超微结构的随增龄变化,同时观察与脑老化密切相关的指标脂褐素沉积。结果在大鼠6月龄之前,随着月龄的增加,海马神经元突触超微结构的发育逐渐完善,至6月龄大鼠突触数量明显增多;此后突触数量逐渐减少,至24月龄大鼠神经元突触数量最少。从1月龄开始海马神经元内即可见少量脂褐素颗粒沉积,随着月龄的逐渐增加,至24月龄时脂褐素颗粒沉积显著。结论青年期大鼠的海马神经元突触发育最好,进入老年期后,突触结构受损,老年期损伤最为严重,同时伴有大量的脂褐素颗粒沉积。

英文摘要：

Objective To observe and compare the ultrastructural changes of synapses in hippocampal neurons in rats with increasing age. Methods The ultrastructure of synapses and lipofuscin granules in hippocampal neurons of Sprague Dawley rats at the age of 1 day, 1, 3, 6, 18 and 24 months were observed by transmission electron microscopy. Results Syaaptic structures in hippocampal neurons were almost absent in the 1-day neonatal rats, gradually increased from 1 month to 6 month-old, then decreased, and almost disappeared at the age of 24 months. The lipofuscin granules emerged in hippocampal neurons of 1 month-old rats, and increased with ageing. The presence of lipefuscin granules was most numerous at 24 months of age. Conclusion Synaptic structures in the rat hippocampus show prominent changes with increasing age, revealed by electron microscopy. Most well developed synaptic structures are present in young rats, and impaired in aged rats, meanwhile there are lots of deposits of lipofuscin granules in the brain neurons of aged rats.