Cornell-Bell A H, Thomas P G, Caffrey J M
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.
Can J Physiol Pharmacol. 1992;70 Suppl:S206-18. doi: 10.1139/y92-264.
Neurons and glia exhibit complex homeostatic interactions via shared extracellular space which can involve metabolites, inorganic ions, and neurotransmitters. Focal application of glutamate to both human and rat central nervous system astrocytes in primary culture produced a rapid, transient increase in both cytoplasmic and nuclear Ca2+. These Ca2+ waves can propagate at up to 15-20 micron/s for long distances (millimetres) through the astrocyte syncitium. Oscillatory Ca2+ signals were frequently observed under control conditions and were enhanced by glutamate application. These Ca2+ signals were paralleled by rapid extensions of filopodia from the astrocyte cell margin and apical surface near the point of glutamate application. Focal application of glutamate to rat hippocampal neurons also elicited rapid, transient increases in intracellular Ca2+. Levels of Ca2+ signals were consistently two- to three-fold greater in pyramidal neurons cultured from CA1 than in those from CA3. Filopodial extension was extensive in CA1 neurons, but rare in CA3 neurons, and in either case observable only during the first few days of primary culture. Diversity of glial and neuronal responses to binding the glutamate receptors may reflect their roles in homeostatic interactions.
神经元和神经胶质细胞通过共享的细胞外空间表现出复杂的稳态相互作用，这可能涉及代谢物、无机离子和神经递质。将谷氨酸局部应用于原代培养的人和大鼠中枢神经系统星形胶质细胞，会使细胞质和细胞核中的钙离子迅速、短暂增加。这些钙波可以以高达15 - 20微米/秒的速度在星形胶质细胞合胞体中远距离（毫米）传播。在对照条件下经常观察到振荡性钙信号，并且谷氨酸的应用会增强这些信号。这些钙信号伴随着丝状伪足从星形胶质细胞边缘和谷氨酸应用点附近的顶端表面迅速延伸。将谷氨酸局部应用于大鼠海马神经元也会引起细胞内钙离子迅速、短暂增加。从CA1培养的锥体神经元中的钙信号水平始终比从CA3培养的锥体神经元中的高两到三倍。丝状伪足延伸在CA1神经元中广泛存在，但在CA3神经元中很少见，并且在任何一种情况下都仅在原代培养的最初几天内可观察到。神经胶质细胞和神经元对谷氨酸受体结合的反应多样性可能反映了它们在稳态相互作用中的作用。
