Alexander John K, Fuss Babette, Colello Raymond J
Department of Anatomy and Neurobiology, Medical College of Virginia, Virginia Commonwealth University, Richmond, USA.
Neuron Glia Biol. 2006 May;2(2):93-103. doi: 10.1017/S1740925X0600010X.
The extension and directionality of neurite outgrowth are key to achieving successful target connections during both CNS development and during the re-establishment of connections lost after neural trauma. The degree of axonal elongation depends, in large part, on the spatial arrangement of astrocytic processes rich in growth-promoting proteins. Because astrocytes in culture align their processes on exposure to an electrical field of physiological strength, we sought to determine the extent to which aligned astrocytes affect neurite outgrowth. To this end, dorsal root ganglia cells were seeded onto cultured rat astrocytes that were pre-aligned by exposure to an electric field of physiological strength (500 mV mm(-1)). Using confocal microscopy and digital image analysis, we found that neurite outgrowth at 24 hours and at 48 hours is enhanced significantly and directed consistently along the aligned astrocyte processes. Moreover, this directed neurite outgrowth is maintained when grown on fixed, aligned astrocytes. Collectively, these results indicate that endogenous electric fields present within the developing CNS might act to align astrocyte processes, which can promote and direct neurite growth. Furthermore, these results demonstrate a simple method to produce an aligned cellular substrate, which might be used to direct regenerating neurites.
在中枢神经系统发育过程以及神经创伤后连接重建过程中，神经突生长的延伸和方向性是实现成功靶连接的关键。轴突伸长的程度在很大程度上取决于富含生长促进蛋白的星形胶质细胞突起的空间排列。由于培养中的星形胶质细胞在暴露于生理强度的电场时会使其突起排列整齐，我们试图确定排列整齐的星形胶质细胞对神经突生长的影响程度。为此，将背根神经节细胞接种到经生理强度电场（500 mV mm(-1)）预排列的培养大鼠星形胶质细胞上。利用共聚焦显微镜和数字图像分析，我们发现24小时和48小时时的神经突生长显著增强，并始终沿着排列整齐的星形胶质细胞突起方向生长。此外，当在固定的、排列整齐的星形胶质细胞上生长时，这种定向神经突生长得以维持。总体而言，这些结果表明发育中的中枢神经系统内存在的内源性电场可能作用于使星形胶质细胞突起排列整齐，从而促进和引导神经突生长。此外，这些结果展示了一种产生排列整齐的细胞基质的简单方法，该方法可用于引导再生神经突。
