大鼠生后中枢神经系统S100B和胶质纤维酸性蛋白表达的变化

目的 探讨SD大鼠生后中枢神经系统发育过程中S100B和胶质纤维酸性蛋白(GFAP)的表达变化.方法 24只雄性SD大鼠分为生后7d、14d、21d和成年4组,用免疫组织化学方法对脑、脊髓切片进行S100B、GFAP抗体染色,观察不同时间点不同部位中两种阳性细胞平均数.结果 生后7d到成年,前额皮质、海马、纹状体、黑质和脊髓S100B阳性标记的密度和数量逐渐减少,生后2～3周时渐趋于稳定;脑内GFAP阳性星形胶质细胞(AST)随年龄增大逐渐增多,突起增粗增长,生后21d GFAP阳性细胞数量已接近成年;相反,脊髓GFAP阳性标记数则随年龄增长呈现由多到少的趋势;海马CAl区生后各年龄段GFAP和S100B免疫荧光双标显示,生后1周至成年S100B阳性细胞的数量明显减少,尤以分子层明显;随年龄增长,双标阳性细胞的比例逐渐增高,多集中分布于锥体细胞层和多形层.结论 大鼠中枢神经系统中S100B和GFAP两种星形胶质细胞蛋白存在不同的表达模式;同时S100B和GFAP蛋白的表达在发育过程中可能受不同机制的调节,并可能代表星形胶质细胞的不同亚型.

POSTNATAL DEVELOPMENT OF S100B AND GFAP IN THE CENTRAL NERVOUS SYSTEM IN RATS

Objective To study the expressions of S100B and glial fibrillary acidic protein(GFAP) in the central nervous system of Sprague-Dawley rats during postnatal development. Methods Twenty-four male SD rats were divided equally into four groups according to different postnatal times:7-day group,14-day group,21-day group and adult group.Immunohistochemistry was used to investigate the expressions of S100B protein and GFAP in the brain and the spinal cord. Results The amount and density of S100B positive astrocytes decreased significantly in frontal cortex,hippocampus,striatum,substantia nigra and spinal cord during postnatal development.It seemed that the second through the third week after birth was a critical period for these changes.The amount and density of GFAP positive AST increased gradually in the brain,but it was the opposite in the spinal cord.Double-labeled immunofluorescence of S100B and GFAP in hippocampus CA1 area showed that S100B positive stains were evenly distributed in the pyramidal,polymorphic and molecular layers from the seventh till the twenty first day after birth,but apparently decreased in each layer especially in the molecular layer in adult hippocampus while the immunoreactivities of GFAP increased.The proportion of double labeled cells also increased with the aging and more of them were found in the pyramidal and polymorphic layers.Conclusion Different patterns of the expressions of S100B and GFAP exist during postnatal development.It may reflect the different roles of these proteins on the glial cell development.And it may also indicate that the expressions of S100B and GFAP are regulated by different mechanisms during the course of development,which reflects the differentiation of subpopulations of astrocytes during ontogenesis.