猫皮层第一体感区髓质胶质反应的年龄相关性变化

Age-related changes of gliosis in the medulla of primary somatosensory area of cat

目的比较青年猫与老年猫大脑皮层第一躯体感觉区(SI区)髓质中胶质细胞和S100蛋白免疫阳性细胞和胶质纤维酸性蛋白(GFAP)免疫阳性细胞的年龄相关性形态学变化,探讨该变化的原因及其在老年性躯体感觉功能衰退中的意义。方法选青年猫与老年猫各4只,用改良的Holzer结晶紫染色显示SI区髓质中所有胶质细胞,并用成年动物Golgi法显示其形态;免疫组织化学法(SABC法)显示S100蛋白免疫阳性(S100-IR)细胞及GFAP免疫阳性(GFAP-IR)细胞。光镜下观察细胞形态,用BI-2000医学图像分析系统计数SI区髓质中的胶质细胞、S100-IR细胞及GFAP-IR细胞的数量,测定S100及GFAP表达的平均吸光度值和阳性细胞面积比。结果与青年猫相比,老年猫SI区髓质中胶质细胞、S100-IR细胞及GFAP-IR细胞密度显著增加(P<0.01),S100-IR细胞及GFAP-IR细胞占胶质细胞的比例均增加,免疫组织化学染色平均吸光度值及阳性细胞面积比也显著增大(P<0.01);星形胶质细胞胞体膨大,突起稠密、粗大。结论衰老过程中,猫SI区髓质中存在明显的反应性胶质化,其中星形胶质细胞对衰老更为敏感。

Objective Age-related morphological changes of glial cells, S100-and glial fibrillary acid protein （GFAP）-immunoreactive cells in the medulla of primary somatosensory area （SI） were comparatively investigated between 4 young cats and 4 old cats, the causation and the effect for these changes were also discussed. Methods Modified Holzer staining was applied to show the total glial cells and the adult animal. Golgi method was used to display the cells＇ morphology; Immunohistochemical method was employed to exhibit Sl00-immunoreactive （S100-IR） and GFAP- immunoreactive （GFAP-IR） cells. Under microscope, the cell morphology was comparatively observed; The numbers of the glial cells, S100-IR and GFAP-IR cells were counted; the average optical density and the area ratio of the immunoreactive cells were calculated with the software of BI-2000. Results The density of the glial cells, S100-IR and GFAP-IR ceils showed a significant increase in the medulla SI of old cats （ P 〈 0.01 ） , accompanied with a notable increased ratio of S100-IR and GFAP-IR cells to the total glial cells. The average absorbance and the area ratio of the positive cells showed a remarkable increase in the old cats than those in the young ones （P 〈 0. 01 ）. In addition, the GFAP-IR astrocytes exhibited larger soma and denser processes in the old animals. Conclusion The medulla of SI exists reactive gliosis during senescence, especially a more sensitivity of the astrocytes, which indicates that an increased glial activity might exert a protective function for aging nervous fibres and might suspend the cortical function degeneration in the seneseeuce.