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ACYL GROUP COMPOSITION OF METABOLICALLY ACTIVE LIPIDS IN BRAIN: VARIANCES AMONG SUBCELLULAR FRACTIONS AND DURING POSTNATAL DEVELOPMENT

Using a combination of preparative TLC and GLC technique, the content and acyl group composition of diacyl‐glycerophosphoinositols, diacyl‐glycerophosphates, diacylglycerols and triacyl‐glycerols in brain tissue were determined. The level of diacyl‐glycerophosphoinositols in 40 day‐old mouse brain was 2.7 μmol/g tissue as compared to 40–170 nmol/g for other minor lipids. The acyl groups of diacyl‐glycerophosphoinositols were enriched in 18:0 and 20:4 (n‐6). This characteristic acyl group profile was found in microsomes, synaptosomes, and in myelin. The acyl groups of diacyl‐glycerophosphates and diacylglycerols were comprised mainly of 16:0, 18:0, 18:1 and 20:4 (n‐6). In rat brain subcellular fractions, the acyl groups of diacylglycerols and diacyl‐glycerophosphates in the microsomal fraction had a higher proportion of 22:6 (n‐3) than those in the myelin and synaptosomal fractions. The acyl groups of the myelin lipids were higher in 18:l and lower in 20:4 (n‐6) as compared to those in the microsomal and synaptosomal fractions. The triacylglycerols in brain exhibited an unusual acyl group profile which included small proportions of 14:0, 16:1, 20:4 (n‐6), 22:4 (n‐6) and 22:6 (n‐3). Except for an increase in 18:1 and a corresponding decrease in 16:0 which was found in diacyl‐glycerophosphoinositols, no apparent acyl group change was observed in other metabolically active lipids during postnatal brain development.