EFFECTS OF DIFFERENT DIETARY LEVELS OF ESSENTIAL FATTY ACIDS ON THE FATTY ACID COMPOSITION OF ETHANOLAMINE PHOSPHOGLYCERIDES IN MYELIN AND SYNAPTOSOMAL PLASMA MEMBRANES

Abstract

Abstract— Three dietary levels of essential fatty acids (EFA), 3 0, 0 75 and 0 07 calorie‐% were fed to rats for two generations or more. Myelin was isolated at the ages of 18, 30, 45 and 120 days and synaptosomal plasma membranes at 18, 30 and 45 days. No difference was found in the lipid composition between the dietary groups in either subcellular fraction. The fatty acid patterns of ethanolamine phosphoglycerides (EPG) were analysed. In myelin the proportions of 18:1 and 20:1 increased with age, while those of 20:4 (n‐6) and 22:6 (n‐3) decreased, in synaptosomal plasma membranes the proportions of 20:4 (n‐6) decreased with age, but 22:6 (n‐3) increased and the sum of the polyunsaturated fatty acids was constant. At no age were significant differences found between the proportions of saturated and monounsaturated fatty acids, in either myelin or the synaptosomal plasma membrane fraction, when the different dietary groups were compared. In myelin from rats fed 007 calorie‐% EFA the proportions of 20:4 (n‐6) were slightly lower than in the two other groups, while those of 22 6 (n‐3) were considerably lower. The synaptosomal plasma membranes fraction of rats fed O‐07 calorie‐% EFA had equal or slightly larger amounts of 20:4 (n‐6) than in the two other groups, while 22:6 (n‐3) was considerably smaller. In both subcellular fractions the decreased proportion of fatty acids of linoleic and linolenic acid series was compensated for by an increase in 20:3 (n‐9) and 22:3 (n‐9). The sum of these two fatty acids was equal in the EPG of myelin and synaptosomal plasma membranes at 18 days of age. At 30 and 45 days of age a lower value was found in the synaptosomal plasma membranes, while in the myelin fraction a slight decrease was found only at 120 days of age.