Incorporation of [1-14C]-oleic acid into neutral glycerides and phosphoglycerides of mouse brain

The incorporation of [1-¹⁴C]-oleic acid into the neutral glycerides and phosphoglycerides of adult mouse brain was examined between 1 and 80 min after intracerebral injection. Radioactivity of the free oleic acid in brain decreased rapidly with a half-life of ca. 5 min. The specific radioactivity of the phosphatidic acids was highest at 1 min after injection. This was followed by the diacylglycerols and triacylglycerols which attained a maximum specific radioactivity at 3 and 20 min after injection, respectively. Specific radioactivities of the neutral glycerides were higher than the phosphoglycerides. A larger proportion of the radioactivity in the diacylglycerols was transferred to the phosphoglycerides than to the triacylglycerols. Among the phosphoglycerides, radioactivity was actively incorporated into the inositol phosphoglycerides. The specific radioactivity of the inositol phosphoglycerides was higher than the diacylsn-glycero-3-phosphorylcholines, and the kinetics of incorporation of radioactivity into these lipids was also different. A water soluble material was found which showed maximum specific radioactivity at 6–10 min after injection. The properties of this water soluble material suggested that it may be an intermediate involved in the acyl group metabolism of phosphoglycerides in brain.