Posse de Chaves E, Vance D E, Campenot R B, Vance J E
Lipid and Lipoprotein Group, University of Alberta, Edmonton, Canada.
J Cell Biol. 1995 Mar;128(5):913-8. doi: 10.1083/jcb.128.5.913.
The goal of this study was to assess the relative importance of the axonal synthesis of phosphatidylcholine for neurite growth using rat sympathetic neurons maintained in compartmented culture dishes. In a double-labeling experiment [14C]choline was added to compartments that contained only distal axons and [3H]choline was added to compartments that contained cell bodies and proximal axons. The specific radioactivity of labeled choline was equalized in all compartments. The results show that approximately 50% of phosphatidylcholine in distal axons is locally synthesized by axons. The requirement of axonal phosphatidylcholine synthesis for neurite growth was investigated. The neurons were supplied with medium lacking choline, an essential substrate for phosphatidylcholine synthesis. In the cells grown in choline-deficient medium for 5 d, the incorporation of [3H]palmitate into phosphatidylcholine was reduced by 54% compared to that in cells cultured in choline-containing medium. When phosphatidylcholine synthesis was reduced in this manner in distal axons alone, growth of distal neurites was inhibited by approximately 50%. In contrast, when phosphatidylcholine synthesis was inhibited only in the compartment containing cell bodies with proximal axons, growth of distal neurites continued normally. These experiments imply that the synthesis of phosphatidylcholine in cell bodies is neither necessary nor sufficient for growth of distal neurites. Rather, the local synthesis of phosphatidylcholine in distal axons is required for normal growth.
本研究的目的是利用培养在分隔培养皿中的大鼠交感神经元，评估轴突合成磷脂酰胆碱对神经突生长的相对重要性。在一项双标记实验中，将[¹⁴C]胆碱添加到仅含有远端轴突的隔室中，将[³H]胆碱添加到含有细胞体和近端轴突的隔室中。使所有隔室中标记胆碱的比放射性相等。结果表明，远端轴突中约50%的磷脂酰胆碱是由轴突在局部合成的。研究了轴突磷脂酰胆碱合成对神经突生长的需求。为神经元提供缺乏胆碱（磷脂酰胆碱合成的必需底物）的培养基。在胆碱缺乏培养基中培养5天的细胞中，与在含胆碱培养基中培养的细胞相比，[³H]棕榈酸掺入磷脂酰胆碱的量减少了54%。当仅远端轴突中的磷脂酰胆碱合成以这种方式减少时，远端神经突的生长受到约50%的抑制。相反，当仅在含有细胞体和近端轴突的隔室中抑制磷脂酰胆碱合成时，远端神经突的生长仍正常继续。这些实验表明，细胞体中磷脂酰胆碱的合成对于远端神经突的生长既非必需也不充分。相反，远端轴突中磷脂酰胆碱的局部合成是正常生长所必需的。
