猫运动皮层神经元和S100、GFAP阳性细胞的年龄相关性变化

比较了青、老年猫运动皮层神经元与S100、GFAP免疫阳性胶质细胞的形态学变化,并探讨其与衰老过程中运动功能衰退的关系。采用Nissl染色显示青、老年猫运动皮层分层结构和神经元。免疫组织化学方法(SABC法)显示青、老年猫运动皮层S100免疫反应阳性(S100-immunoreactive,S100-IR)细胞及胶质纤维酸性蛋白免疫反应阳性(GFAP-immunoreactive,GFAP-IR)细胞。在Olympus显微镜下,用Moitcam5000数码成像与分析系统计数运动皮层各层神经元、S100-IR细胞及GFAP-IR细胞的数量,并随机抽样测量S100-IR、GFAP-IR细胞的胞体直径。与青年猫相比,老年猫运动皮层Ⅴ、Ⅵ层神经元密度显著下降(P<0.01),老年猫运动皮层中S100-IR和GFAP-IR细胞密度与胞体直径均显著增加(P<0.01),且细胞的免疫阳性反应较强。研究结果表明,猫运动皮层的神经元密度在衰老过程中Ⅴ、Ⅵ层神经元密度显著下降,有可能会降低老年个体运动皮层对运动的调控能力;随着衰老、运动皮层的星形胶质细胞出现明显的反应性活化与增生,这对维持大脑运动皮层神经元的活性和神经元之间的通讯联系,从而延缓老年性运动功能衰退具有重要意义。

Age-Related Changes in Neurons and S100-, GFAP-Immunoreactive Cells in the Motor Cortex of Cats

Morphological changes of neurons and S100-,GFAP-immunoreactive cells in the motor cortex of young adult and older cats were comparatively investigated, and the correlation of these changes and motor function degradation during senescence was discussed. Nissl staining was applied to show cortical layers and neurons. Immunohistochemical method was employed to exhibit S100-immunoreactive (S100-IR) and GFAP-immunoreactive (GFAP-IR) cells. Under an Olympus microscope, Moitcam 5000 Digital Image Acquisition and Analysis System was used to statistically count the number of total cortical neurons, GFAP-IR cells and S100-IR cells in each cortical layer, and the cell-body diameter of GFAP-IR cells and S100-IR cells were randomly sampled and measured. The density of total neurons in layer V and VI of the motor cortex showed a significant decrease in older cats (P < 0.01). Furthermore, the density and the cell-body diameter of GFAP-IR and S100-IR cells in the motor cortex of old cats were significantly increased when compared to that in young adults (P < 0.01). In addition,the S100 and GFAP immunoreactivity in the motor cortex of older cats was stronger than in younger ones. The density of total neurons in layer V and VI of the motor cortex was significantly reduced during aging, which might lead to a decreased motion mediation capacity of the motor cortex in older individuals. Moreover, with age, astrocytes in the motor cortex were significantly activated and increased, which is of great significance in maintaining normal neuronal activities, signalling between neurons and therefore slowing down age-dependent motor function degradation.