老年大鼠脑白质损害在学习记忆降低中的意义  

The significance of white matter lesion in decline of learning and memory during aging

作　　者：赵士福[1] 成戎川[1] 刘磊[1] 金燕[1] 肖道宏[1] 

机构地区：[1]第三军医大学新桥医院神经内科,重庆400037

出　　处：《中国老年学杂志》2006年第5期638-640,共3页Chinese Journal of Gerontology

基　　金：国家自然科学基金项目(NO.3970004230170311)

摘　　要：目的探讨老化时轴突及髓鞘结构和成分变化在学习记忆功能改变中的意义。方法使用穿梭箱、电镜和免疫组织化学技术,观察老年大鼠学习、记忆维持功能、髓鞘和轴突的超微结构改变,以及髓鞘碱性蛋白表达变化。结果在训练第1天至第6天,老年大鼠主动逃避反应率(AAR)、总逃避反应率(GAR)较青年组显著减慢(P<0.01),逃避潜伏时(LER)较青年组延长(P<0.01),训练第6天GAR青年组达到89.0%,老年组为40.5%,LER青年组为3.16 s,老年组为6.10 s。在记忆功能维持上,训练后第5天和第10天,老年组大鼠AAR、GAR很快降低,LER明显升高(P<0.01)。老年大鼠髓鞘异常为轴突周围间隙扩大,髓鞘致密层分离,部分板层结构破坏,髓鞘内形成大泡,轴突直径增加,轴突内含有吞噬小泡、致密颗粒和巨大线粒体,少突胶质细胞电子密度增加。老年大鼠髓鞘碱性蛋白(MBP)表达下降。结论老年大鼠学习及记忆维持能力降低,老化可以导致轴突及髓鞘的结构变化,MBP表达降低,髓鞘结构和成分改变可能参与老化时学习和记忆损害。Objective To investigate the significance of axon and myelin structures and components in decline of learning and memory during aging. Methods The learning and the maintenance of memory, the changes of the ultrastructure in myelin and axon, and the expression of myelin basic protein （MBP） were observed by the shuttle box apparatus, electron microscope and immunohistochemistry in aged rat. Results During 1 ～ 6 days of behavior training, active avoidance response （AAR） and general avoidance response （GAR） were slower significantly （ P 〈 0. 01 ）, latency of escaping response （LER） prolonged significantly （ P 〈 0. 01 ） in aged group than those in young group. GAR was 40. 5% and 89. 0%, LER was 6. 10 and 3. 16 s respectively in the aged group and young group at the 6th day during training. AAR and GAR decreased fast, LER increased sharply in aged group at the 5th and 10th day after training in aged group than those in young group （P 〈 0.01 ）. The common abnormalities of the myelin sheaths in aged rat were a distended periaxonal space between axon and myelin sheaths, splitted dense line of myelin sheaths, damaged lamellae structure, formed blister in the sheath, increased axon diameter, enlarged axons contained vacuoles and dense granules, giant mitochondria （Mt） and enhanced electron density in cytoplasm of oligodendrucyte, and reduced MBP expression in aged rats. Conclusions The learning and memory were reduced with aging. Aging could result in the structure changes of axon and myelin, and decline of MBP expression. The alteration in structure and components in myelin might contribute to the injury of learning and memory during aging.

关 键 词：脑老化 学习记忆 髓鞘 碱性髓鞘蛋白 

分 类 号：R742[医药卫生—神经病学与精神病学]