Kiss J Z
Department of Morphology, University of Geneva Medical School, Switzerland.
Mol Cell Endocrinol. 1998 May 25;140(1-2):89-94. doi: 10.1016/s0303-7207(98)00034-3.
Glial cells are exquisitely sensitive to changes in neuronal activity, and their capacity for structural plasticity including migration is critical for remodeling an repair of nervous tissue. Our in vitro studies suggest that isoforms of the neural cell adhesion molecule (NCAM) carrying an unconventional carbohydrate polymer, polysialic acid (PSA), are involved in these events. We have demonstrated that neurohypophyseal explants from newborn rats generate cellular outgrowth of immature astrocytes displaying the characteristics of oligodendrocyte-type 2 astrocyte (O-2A) progenitor cells previously identified in the optic nerve. Treatment of O-2A cells with the enzyme Endo N, which specifically removes PSA from the cells surface, produced a complete blockade of the dispersion of the O-2A cell population from the explant. Identical effects of Endo N were observed in migration assays using cortical O-2A cells. Neurohypophyseal O-2A cells express functional NMDA class of glutamate receptors and the pharmacological blockade of these receptors inhibit PSA-NCAM biosynthesis and dramatically diminish O-2A cell migration from neurohypophyseal explants. This suggests a potential mechanism through which neuronal activity via glutamate release may regulate PSA-NCAM expression on immature glial cells, which in turn is critical for their migration.
神经胶质细胞对神经元活动的变化极为敏感，其包括迁移在内的结构可塑性能力对于神经组织的重塑和修复至关重要。我们的体外研究表明，携带非常规碳水化合物聚合物多唾液酸（PSA）的神经细胞黏附分子（NCAM）同工型参与了这些过程。我们已经证明，新生大鼠的神经垂体外植体可产生未成熟星形胶质细胞的细胞生长，这些细胞表现出先前在视神经中鉴定出的少突胶质细胞2型星形胶质细胞（O-2A）祖细胞的特征。用内切酶N（Endo N）处理O-2A细胞，该酶可特异性地从细胞表面去除PSA，导致O-2A细胞群体从外植体分散的完全阻断。在使用皮质O-2A细胞的迁移试验中观察到Endo N具有相同的作用。神经垂体O-2A细胞表达功能性的NMDA类谷氨酸受体，这些受体的药理学阻断抑制PSA-NCAM生物合成，并显著减少O-2A细胞从神经垂体外植体的迁移。这提示了一种潜在机制，通过该机制，经由谷氨酸释放的神经元活动可能调节未成熟神经胶质细胞上PSA-NCAM的表达，而这反过来对它们的迁移至关重要。
