Locally Synthesized Phosphatidylcholine, but Not Protein, Undergoes RapidRetrograde Axonal Transport in the Rat Sciatic Nerve

摘要

Retrograde axonal transport of phosphatidylcholine in the sciatic nerve has beendemonstrated only after injection of lipid precursors into the cell body region. After microinjection (1 microliters) of (methyl-(3)H)choline chloride into the rat sciatic nerve (35-40 mm distal to the L4 and L5 dorsal root ganglia), time-dependent accumulation of (3)H-labeled material occurred in dorsal root ganglia ipsilateral, but not contralateral, to the injection site. The level of radioactivity in the ipsilateral dorsal root ganglia was minimal at 2 h after isotope injection but was significantly increased at 7, 24, 48, and 72 h after intraneural isotope injection (n = 3-8 per time point); at these time points, all of the radiolabel in the chloroform/methanol extract of the ipsilateral dorsal root ganglia was present in phosphatidylcholine. The radioactivity in the water-soluble fraction did not show a time-dependent accumulation in the ipsilateral dorsal root ganglia as compared with the contralateral DRGs, ruling out transport or diffusion of precursor molecules. In addition, colchicine injection into the sciatic nerve proximal to the isotope injection site prevented the accumulation of radiolabel in the ipsilateral dorsal root ganglia. Therefore, this time-dependent accumulation of radiolabeled phosphatidylcholine in the ipsilateral dorsal root ganglia is most likely due to retrograde axonal transport of locally synthesized phospholipid material. (Copyright (c) 1993 International Society for Neurochemistry.)