Padilla S, Pope C N
Cellular and Molecular Toxicology Branch, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711.
J Neurochem. 1991 Aug;57(2):415-22. doi: 10.1111/j.1471-4159.1991.tb03768.x.
Although autoradiography has demonstrated local incorporation of [3H]inositol into axonal phospholipids after intraneural injection, retrograde axonal transport of phosphatidylinositol has only been demonstrated after injection of lipid precursor into the cell body regions (L4 and L5 dorsal root ganglia) of the sciatic nerve. We now report the retrograde axonal transport of inositol phospholipids synthesized locally in the axons. Following microinjection of myo-[3H]inositol into the rat sciatic nerve (50-55 mm distal to L4 and L5 dorsal root ganglia), a time-dependent accumulation of 3H label occurred in the dorsal root ganglia ipsilateral to the injection site. The ratio of dpm present in the ipsilateral dorsal root ganglia to that in the contralateral dorsal root ganglia was not significantly different from unity between 2 and 8 h following isotope injection but increased to 10-12-fold between 24 and 72 h following precursor injection. By 24 h following precursor injection, the ipsilateral/contralateral ratio of the water-soluble label in the dorsal root ganglia still remained approximately 1.0, whereas the corresponding ratio in the chloroform/methanol-soluble fraction was approximately 20. The time course of appearance of labeled lipids in the ipsilateral dorsal root ganglia after injection of precursor into the nerve at various distances from the dorsal root ganglia indicated a transport rate of at least 5 mm/h. Accumulation of label in the dorsal root ganglia could be prevented by intraneural injection of colchicine or ligation of the sciatic nerve between the dorsal root ganglia and the isotope injection site. These results demonstrate that inositol phospholipids synthesized locally in the sciatic nerve are retrogradely transported back to the nerve cell bodies located in the dorsal root ganglia.
尽管放射自显影已证明在神经内注射后[3H]肌醇可局部掺入轴突磷脂中，但磷脂酰肌醇的逆行轴突运输仅在将脂质前体注射到坐骨神经的细胞体区域（L4和L5背根神经节）后得到证实。我们现在报告在轴突中局部合成的肌醇磷脂的逆行轴突运输。将肌醇-[3H]肌醇微量注射到大鼠坐骨神经中（距L4和L5背根神经节远端50-55毫米）后，注射部位同侧的背根神经节中出现了3H标记的时间依赖性积累。同位素注射后2至8小时，同侧背根神经节中存在的每分钟衰变数与对侧背根神经节中的比值与1无显著差异，但在前体注射后24至72小时之间增加到10-12倍。在前体注射后24小时，背根神经节中水溶性标记的同侧/对侧比值仍约为1.0，而氯仿/甲醇可溶部分中的相应比值约为20。在距背根神经节不同距离处将前体注射到神经中后，同侧背根神经节中标记脂质出现的时间进程表明运输速率至少为5毫米/小时。神经内注射秋水仙碱或在背根神经节与同位素注射部位之间结扎坐骨神经可防止背根神经节中标记的积累。这些结果表明，坐骨神经中局部合成的肌醇磷脂被逆行运输回位于背根神经节中的神经细胞体。
