Spoerri P E, Dozier A K, Roisen F J
Department of Anatomical Sciences and Neurobiology, University of Louisville, School of Medicine, KY 40292.
Brain Res Dev Brain Res. 1990 Nov 1;56(2):177-88. doi: 10.1016/0165-3806(90)90080-i.
Cultures of mouse Neuro-2a neuroblastoma cells treated with 3-6 mM extracellular Ca2+ exhibited enhanced neurite extension characterized by increased neurite numbers and lengths. The ganglioside GM1 potentiated the effect of extracellular Ca2+ by increasing further the number and length of the neurites formed in response to exogenous Ca2+. Maximal neuritic numbers were achieved with 4 mM Ca2+ while the longest neurites were observed in medium containing 4-6 mM Ca2+. Stimulation of the Ca2+ influx with the ionophore A23187 or the amino acid taurine also enhanced neurite formation and GM1 potentiated these actions. Transmission electron microscopy revealed numerous microtubules and neurofilaments in neurites and microfilaments with the spine-like processes along fine neuritic branches and in the filopodia of growth cones. Neuritic varicosities and growth cones contained a variety of vesicles. All of these structures were increased in the presence of GM1 and were increased further by extracellular Ca2+ or A23187. The ability of GM1 to enhance neuritogenesis was diminished by EGTA or Ruthenium red. Similarly, the effect of GM1 was diminished or abolished by Ca2+ channel blockers such as CdCl2 or LaCl3. X-ray microprobe analysis revealed that GM1 alone enhanced intracellular levels of total ionic and membrane bound Ca2+, perhaps accounting for the increased neuritogenesis observed under conditions in which Ca2+ was manipulated. The present study suggest that the neuritogenic action of GM1 is Ca2+ dependent.
用3 - 6 mM细胞外Ca2+处理的小鼠Neuro-2a神经母细胞瘤细胞培养物表现出神经突延伸增强，其特征为神经突数量和长度增加。神经节苷脂GM1通过进一步增加响应外源性Ca2+形成的神经突数量和长度来增强细胞外Ca2+的作用。4 mM Ca2+时可达到最大神经突数量，而在含有4 - 6 mM Ca2+的培养基中观察到最长的神经突。用离子载体A23187或氨基酸牛磺酸刺激Ca2+内流也增强了神经突形成，并且GM1增强了这些作用。透射电子显微镜显示神经突中有大量微管和神经丝，以及沿着细神经突分支和生长锥丝状伪足的带有棘状突起的微丝。神经突膨体和生长锥含有多种囊泡。在GM1存在的情况下，所有这些结构都增加了，并且通过细胞外Ca2+或A23187进一步增加。EGTA或钌红可减弱GM1增强神经突生成的能力。同样，GM1的作用被Ca2+通道阻滞剂如CdCl2或LaCl3减弱或消除。X射线微探针分析显示，单独的GM1可提高细胞内总离子钙和膜结合钙的水平，这可能解释了在操纵Ca2+的条件下观察到的神经突生成增加。本研究表明GM1的神经突生成作用是Ca2+依赖性的。
