title: Peripheral nerve sphingomyelin and cerebroside are both formed via two metabolically and kinetically distinct pathways in vivo.
abstract: We have studied the labeling kinetics of peripheral nerve sphingolipids in vivo. The kinetic analysis of the labeling profiles observed for the various sphingolipids demonstrated that 90% of cerebrosides, but only 30% of sphingomyelin, were synthesized via a de novo synthesized ceramide intermediate following the injection of 1-4 pmol [3H]palmitate into mouse sciatic nerves. The remaining sphingolipid labeling (30% of the total) was due to direct acylation events, using free fatty acids originating from a pool different from those implicated in the de novo ceramide pathway. Direct acylation events ceased within 1 h following substrate administration, while labeling via the ceramide pathway continued through 5 h. The results provide the first in vivo demonstration that the formation of cerebrosides and sphingomyelin in peripheral nerves in situ can be simultaneously assured via two metabolically and kinetically distinct pathways that employ different fatty acid pools.
authors.affiliation: Laboratory of Membrane Biogenesis, C.N.R.S.-URA 1811, Université de Bordeaux II, France.
authors.forename: A M
authors.initials: AM
authors.lastname: Heape
authors.forename: F
authors.initials: F
authors.lastname: Boiron
authors.forename: J J
authors.initials: JJ
authors.lastname: Bessoule
authors.forename: C
authors.initials: C
authors.lastname: Cassagne
mesh_terms: D000215:Acylation; D000818:Animals; D002518:Ceramides / Q000378:metabolism; D002554:Cerebrosides / Q000096:biosynthesis*; D007700:Kinetics; D051379:Mice; D008808:Mice, Inbred CBA; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D010525:Peripheral Nerves / Q000378:metabolism*; D012584:Sciatic Nerve / Q000378:metabolism; D013109:Sphingomyelins / Q000096:biosynthesis*; D014316:Tritium
chemical_list: D002518:Ceramides; D002554:Cerebrosides; D010169:Palmitic Acids; D013109:Sphingomyelins; D014316:Tritium; D019308:Palmitic Acid