As indicated by our previous electrophysiological investigations , the responsiveness of visual cortical neurons to visual stimulation in cat showed a significant functional degradation during aging. There is no direct evidence to testify whether this functional degradation is accompanied by a glial activity changes. Using cats from previous electrophysiological experiments as materials , we examined morphologically aged-dependent changes of astrocyte activity in the primary visual cortex ( V1) of young adult and old cats. Nissl staining was used to display cortical histological structure and locate cortical layers. Immunohistochemical method ( SABC method) was applied to visualize GFAP immunoreactive cells. Under the microscope, GFAP-IR cells were counted, and their body diameter were measured. The mean density of GFAP-IR cells in each cortical layer and the white matter of V1 in old cats were significantly higher than those in young adult cats ( p ＜ 0. 001) . Compared with that of young adult cats , the mean diameter of astrocytes in both gray matter and white matter of old cats was significantly increased ( p ＜ 0. 0001) . Further, GFAP immunoreaction intensity in the primary visual cortex of old cats was stronger than that of young adult ones. The functional degradation of neurons in the visual cortex of old cats was accompanied by an improved activity of astrocytes, which could be beneficial to communication between neurons and thus may compensate neuronal function declines during senescence.%电生理研究结果显示,在衰老过程中猫的视皮层神经元对视觉刺激的反应性出现显著的功能衰退,是否这种功能性衰退伴随胶质细胞活动的改变尚无直接的实验证据.以前期电生理实验猫为材料,用免疫形态学方法比较青年猫和老年猫初级视皮层内星形胶质细胞的活动状况.利用Nissl染色显示猫初级视皮层组织结构,用免疫组织化学方法(SABC法)显示GFAP免疫阳性(GFAP-IR)星形胶质细胞.光镜下观察、拍照,对GFAP-IR细胞计数并换算成密度,测量GFAP-IR直径取平均值.老年猫初级视皮层灰质各层及白质内的GFAP-IR细胞密度比青年猫的显著升高(P<0.001).与青年猫相比,老年猫视皮层灰质和白质中GFAP-IR细胞的平均直径均比青年猫的显著增大(P<0.0001),且老年猫视皮层内GFAP阳性免疫反应较青年猫的明显增强.老年猫初级视皮层神经元功能衰退伴随着星形胶质细胞活动的增强,胶质细胞活动增强有助于神经元之间的信息交流,因而可能对衰老过程中神经元的功能衰退起补偿作用.
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