Axon-myelin transfer of glycerol-labeled lipids and inorganic phosphate during axonal transport

Robert W. Ledeen, James E. Haley

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Axon-to-myelin transfer of lipids and lipid precursors have been studied in the rabbit optic system by intraocular injection of [32P]orthophosphate, [14C]glycerol and [3H]glycerol. Choline and ethanolamine phosphoglycerides and myelin showed increasing [32P]-radioactivity between 7 and 21 days following injection, while [3H]- and [14C]-radioactivities remained relatively constant. The latter radioactivities decreased, however, in all the axon- and axolemma-enriched fractions during the same period. These findings supported the concept that a portion of substances undergoing axonal transport enters the pool of myelin lipids by two mechanisms: transcellular transfer of intact lipid and axon-myelin transfer of precursors which are re-utilized for lipid biosynthesis by myelin-localized enzymes. The present study shows that inorganic phosphate, possibly generated by catabolic activity within the axon, is able to enter myelin and participate in the re-utilization mechanism as previously described for serine, choline and acyl chains. The relative invariance of the 3H:14C ratio suggested that the majority of glycerol is not re-utilized in this manner but probably enters myelin through transfer of intact lipid. These and earlier results suggest a possible form of metabolic dependence of myelin on trophic substances from the axon.

Original languageEnglish (US)
Pages (from-to)267-275
Number of pages9
JournalBrain research
Issue number2
StatePublished - Jun 20 1983
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Neuroscience
  • Molecular Biology
  • Clinical Neurology
  • Developmental Biology


  • axon-myelin transfer
  • axonal transport
  • myelin
  • phospholipids


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