老年学习记忆减退大鼠海马GABA能神经元树突内线粒体的变化

为进一步探讨ＧＡＢＡ 能神经元与老年学习记忆减退的关系，本研究以老年学习记忆减退大鼠为模型，用免疫电镜结合体视学方法观察了老年学习记忆减退大鼠海马ＣＡ１ 区放射 分子层的ＧＡＢＡ 能神经元树突内线粒体的改变。结果显示，线粒体的面数密度在老年学习记忆损害组明显小于青年组和老年正常组（Ｐ＜ ０．０１）；体密度的绝对值有所减少，但无统计学意义（Ｐ＞０．０５）。此外，衰老时较小的树突内线粒体的密度增大，老年学习记忆正常组小直径树突内线粒体面数密度的增加较老年学习记忆损害组更明显。结果提示，衰老过程中，ＧＡＢＡ 阳性树突内线粒体的数目减少，单个线粒体的体积代偿性增大。老年学习记忆减退时，树突结构和功能的内源性代偿能力下降，可能处于一种失代偿状态。

CHANGE OF MITOCHONDRIA IN THE GABAERGIC DENDRITE IN HIPPOCAMPUS OF AGED LEARNING AND MEMORY IMPAIRED RATS

The purpose of this study was to explore the behavioral feature and its relation to the mitochondria in GABAergic dendrites of the aged rat. Forty aged SD rats(24 months) were divided into aged impaired group and aged unimpaired group according to the swimming time of platform trial performance in the Morris water maze. Fifteen young rats (3 months) were used as control. The changes of mitochondria in GABAergic dendrites of hippocampal formation were estimated by immunoelectron microscopy and stereological method. The results showed that the average area densities(N A) of mitochondria in GABAergic dendrites were decreased in aged impaired rats compared to young rats and aged unimpaired rats (P<0.01). The volume density(Vv) of mitochondria was decreased in aged rats, but no significant differences were seen in the three groups. The GABAergic dendrites were then classified according to their diameter. It was found that the smaller densities, the more mitochondria. Comparing to the aged impaired rats, there were many more mitochondria in the smaller dendrites of aged unimpaired rats. The results suggest that the number of mitochondria in the GABAergic dendrites was decreasing and the volume of single mitochondria was increasing during aging. The dendritic structure and function may be in a failing compensatory state in the aged learning and memory impaired rats.