In vivo labeling of myelin lipids and proteolipid protein with [3H]myristate, [14C]linoleate, and [14C]linolenate.
To investigate the incorporation of essential fatty acids into myelin components, 24-day-old rabbits were injected intracerebrally with [14C]linoleate, [14C]linolenate, or [3H]myristate for comparison. Animals were killed 22 hr later and myelin was isolated. [3H]myristate labeled all myelin lipids including monogalactosyl diglyceride, with the exception of sulfatides. With 14C-essential fatty acids, only glycerophospholipids were efficiently labeled and their specific activities were in the following decreasing orders: PC greater than PI greater than PE greater than PS with [14C]linoleate, and PE greater than PC greater than PI = PS with [14C]linolenate. Among myelin proteins, PLP and DM-20 were labeled with all 3 precursors. PLP was purified from myelin labeled with 14C-essential fatty acids. The label was then cleaved from the protein by alkaline methanolysis and was identified as a dienoic [( 14C]linoleate) or a tetraenoic [( 14C]linolenate) fatty acid. MBP was not labeled with [3H]myristate, but was slightly labeled with both 14C-essential fatty acids. The signification of the latter result is discussed.
Bürgisser
P
P
Service de Pédiatrie, Centre Hospitalier, Universitaire Vaudois, Lausanne, Switzerland.
Matthieu
J M
JM
D000818:Animals; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism*; D008042:Linolenic Acids / Q000378:metabolism*; D050356:Lipid Metabolism; D009185:Myelin Proteins / Q000378:metabolism*; D018991:Myelin Proteolipid Protein; D009186:Myelin Sheath / Q000378:metabolism*; D019814:Myristic Acid; D009227:Myristic Acids / Q000378:metabolism*; D011817:Rabbits; D017962:alpha-Linolenic Acid
D008041:Linoleic Acids; D008042:Linolenic Acids; D009185:Myelin Proteins; D018991:Myelin Proteolipid Protein; D009227:Myristic Acids; D019814:Myristic Acid; D017962:alpha-Linolenic Acid; D019787:Linoleic Acid