Nomura T, Yabe T, Rosenthal E S, Krzan M, Schwartz J P
Neurotrophic Factors Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-4126, USA.
J Neurosci Res. 2000 Sep 15;61(6):588-96. doi: 10.1002/1097-4547(20000915)61:6<588::AID-JNR2>3.0.CO;2-M.
6-hydroxydopamine (6-OHDA) lesion of the substantia nigra (SN) causes the appearance of reactive astrocytes not only in the SN but also in the striatal terminal fields, as measured by increased size of the cells and their processes, as well as enhanced expression of glial fibrillary acidic protein (GFAP) and an epitope recognized by monoclonal antibody 19D1. We now demonstrate that polysialylated neural cell adhesion molecule (PSA-NCAM) is induced on reactive astrocytes, as well as on large neurons, on the ipsilateral side of the 6-OHDA-lesioned SN. Colocalization of GFAP and PSA-NCAM was confirmed for reactive astrocytes using a confocal laser scanning microscope. Negligible amounts of PSA-NCAM reactivity were detected contralaterally, although colocalization was noted on astrocytes with sparse, significantly thinner processes. In contrast to the increase of GFAP in the lesioned striatum, few striatal astrocytes expressed PSA-NCAM. In agreement with these results, PSA-NCAM was detected on cultured reactive astrocytes from SN but not reactive striatal astrocytes. Double immunohistochemistry for proliferating cell nuclear antigen (PCNA), a marker of dividing cells, and GFAP demonstrated that reactive astrocytes in lesioned SN were PCNA-positive whereas those in striatum were not. Although NG2 chondroitin sulfate proteoglycan expression also increased in the lesioned SN, NG2 was not colocalized with PSA-NCAM, was not expressed on astrocytes, and labeled only oligodendrocyte precursor cells. Our results suggest that PSA-NCAM can act as a marker for reactive astrocytes only at the site of the lesion and not in the terminal fields, probably because it is reexpressed only when astrocytes divide.
黑质（SN）的6-羟基多巴胺（6-OHDA）损伤不仅会导致SN中出现反应性星形胶质细胞，还会在纹状体终末区域出现，这可通过细胞及其突起大小的增加、胶质纤维酸性蛋白（GFAP）表达的增强以及单克隆抗体19D1识别的表位来衡量。我们现在证明，在6-OHDA损伤的SN同侧，多唾液酸神经细胞黏附分子（PSA-NCAM）在反应性星形胶质细胞以及大神经元上被诱导表达。使用共聚焦激光扫描显微镜证实了GFAP和PSA-NCAM在反应性星形胶质细胞中的共定位。虽然在对侧检测到的PSA-NCAM反应性可忽略不计，但在具有稀疏、明显较细突起的星形胶质细胞上也观察到了共定位。与损伤纹状体中GFAP的增加相反，很少有纹状体星形胶质细胞表达PSA-NCAM。与这些结果一致，在来自SN的培养反应性星形胶质细胞上检测到了PSA-NCAM，但在反应性纹状体星形胶质细胞上未检测到。对增殖细胞核抗原（PCNA，一种分裂细胞的标志物）和GFAP进行双重免疫组织化学分析表明，损伤SN中的反应性星形胶质细胞PCNA呈阳性，而纹状体中的反应性星形胶质细胞则不是。虽然损伤的SN中NG2硫酸软骨素蛋白聚糖表达也增加，但NG2与PSA-NCAM不共定位，不在星形胶质细胞上表达，仅标记少突胶质细胞前体细胞。我们的结果表明，PSA-NCAM可能仅在损伤部位作为反应性星形胶质细胞的标志物，而在终末区域则不然，这可能是因为它仅在星形胶质细胞分裂时重新表达。
