Which type of lipid is found in high concentrations in the myelin sheath of nerve cells?
Myelin ultrastructure demands lipid composition favoring extremely stable insulating multilamellar wraps reducing capacitance increasing resistance for saltatory conduction. Oligodendrocyte Schwann cell myelin contains seventy percent lipid eighty percent dry weight enriched sphingolipids galactosylceramide twenty three percent sulfatide four percent sphingomyelin eight percent plus cholesterol twenty eight percent compared plasma membrane choline phospholipids lower PC ten PE fifteen phosphatidylethanolamine. Sphingomyelin amide linked saturated very long chain fatty acids C22 C24 C26 promotes tight packing interdigitation hydrogen bonding sphingosine OH amide raising thickness five nanometers increasing electrical resistance hundred fold enabling conduction velocity up to one hundred meters per second Nodes Ranvier. Enzymes CGT UDP galactose ceramide galactosyltransferase CERS2 ceramide synthase essential myelin synthesis deficiency causes dysmyelination tremor ataxia. Degradation arylsulfatase A deficiency leads metachromatic leukodystrophy sulfatide storage demyelination. Enrichment explains detergent insolubility myelin slow turnover half life months vulnerability autoimmune demyelination multiple sclerosis targeting myelin lipid protein complexes MAG MOG PLP neurobiology concept pathology examination focus central nervous system disease mechanisms and lipid biochemistry.
Ref: Quarles et al., Neurochemical myelin membranes sphingomyelin high concentration, in Basic Neurochemistry 2012.