Lipid synthesis by oligodendrocytes from adult pig brain maintained in long-term culture

Oligodendrocytes were isolated from adult pig brain and cultivated for 18-24 days. [(14)C]acetate, [(3)H]galactose or [(35)S]sulfate were added to the medium for an additional 24 h. Lipids were extracted and separated by high-performance thin-layer chromatography. The labeled lipids were studied by fluorography and scintillation counting. [(14)C]acetate was incorporated in decreasing order into neutral lipids, phosphatidylcholine, ethanolamine phosphatides, galactocerebrosides, phosphatidylinositol, phosphatidylserine, sulfatides and sphingomyelin. From the [(14)C]acetate incorporated into ethanolamine and choline phosphatides, 71.6 and 14.8%, respectively, were found in plasmalogens. Among neutral lipids, [(14)C]acetate labeled not only cholesterol but also large amounts of triglycerides. No cholesterol esters were synthesized. [(3)H]galactose primarily labeled galactocerebrosides, sulfatides, and monogalactosyl diglyceride. [(35)S]sulfate incorporation was restricted to sulfatides. Together with our previous results concerning proteins, these data show that: (1) oligodendrocytes remain highly differentiated in long-term cultures; (2) they are able to synthesize the major components of myelin; (3) they synthesize surprisingly high amounts of triglycerides and of monogalactosyl diglyceride, a marker for myelination.