老年记忆减退大鼠海马CA1区锥体细胞和神经毡线粒体的体视学研究

A quantitative study of hippocampal mitochondria in CAl pyramidal cells and neuropiles in senile memory-impaired rats

目的 应用电镜观察老年记忆损害大鼠海马线粒体的形态学改变.方法 青年(3月龄)和老年(26月龄)SD大鼠经Morris水迷宫测试后,以青年鼠平均逃避潜伏期正常值上限的95%和99%上限值为界将老年鼠分为老年记忆正常组和老年记忆减退组.用透射电镜观察海马CA1锥体细胞和神经毡内线粒体的体视学参数.结果 1.与青年大鼠相比,老年记忆正常大鼠海马线粒体数密度(Nv)、比膜面(Sm)、比表面(Ss)下降显著,但体密度(Vv)与青年大鼠相比无显著差异;老年记忆减退大鼠海马线粒体Nv、Ss、Sm、Vv均下降显著,且Vv、Nv的下降与老年记忆正常大鼠间有显著差异;2.老年记忆减退大鼠和老年记忆正常大鼠线粒体平均体积(V)均较青年组明显增加,但两老年组间无差异.讨论 线粒体的形态学参数体现了老年期海马线粒的代偿改变,而线粒体的功能失调可能在老年记忆损害中起重要作用.

Objective To observe the morphological changes of hippocampal mitochondria in senile memory impaired rats. Methods Young(3 months) and aged(26 months) female SD rats were tested in the Morris water maze.The aged rats were divided into senile memory-impaired group( escape latency > 48. 2sec) and senile memory-unimpaired group( escape latency < 38.8 sec) , according to the 99 % and 95 % upper limits of the mean escape latency of the young rats. Stereological parameters of mitochondria in hippocampal CA1 pyramidal cells and neuropiles were analyzed on TEM graphs.Results 1 .Compared with the young rats,the mitochondrial numerical density(Nv) .specific surface (Ss) ,and specific membrane(Sm) remarkably decreased in the senile memory-umimpaired group, whereas in the senile memory impaired group the mitochondrial Nv, Ss, Sm, and Vv were all remarkably lower than the ones in the young rats. In addition, the differences in Vv and Nv be-tween the two senile groups were significant. 2. The mitochondrial average volum( V) increased significantly in both senile groups and there was no remarkable difference observed between them. Conclusion Our results suggested that the changes of hippocampal mitochondria might sup-port mitochondrial compensation in senile hippocampus and the malfunction of the hippocampal mitochondria might play an important role in the senile memory impairment.