Changes in the Fatty Acid Patterns of Brain Phospholipids during Development of Rats Fed Peanut or Rapeseed Oil, Taking into Account Differences between Milk and Maternal Food

Abstract

The nature and amount of essential fatty acids in dietary fat play a leading part in the repartition of brain polyunsaturated fatty acids (n-3 and n-6). To determine precisely the respective roles of linolenic and linoleic acids in the diet on rat brain development, 2 diets were used in which the percentage of linolenic acid (18:3 n-3) was different. The animals were fed peanut oil (group A) or rapeseed oil (group B) during pregnancy and throughout lactation. The study of the fatty acid composition of gastric milk showed that the levels of linoleic acid (18:2 n-6) and more so linolenic acid (18:3 n-3) were much lower than in dietary fats. In group B, the 18:3 n-3 level of gastric content was .apprx. 4 times lower (2.4%) than in the maternal diet (8.5%) at the beginning of the suckling period and significantly increased until weaning. Analysis of the fatty acid composition of ethanolamine phosphoglycerides showed that docosapentaenoic acid .DELTA.7-10-13-16-19 (22:5 n-3) and docosahexaenoic acid .DELTA.4-7-10-13-16-19 (22:6 n-3) levels increased in group B in relation to group A, and the docosapentaenoic acid .DELTA.4-7-10-13-16 (22:5 n-6) level decreased in group B. The sum of (n-3 + n-6) fatty acids did not change in either group B or group A. No marked effect of diet composition was found upon conversion of linoleic acid to arachidonic acid. Linolenic acid can be utilized in the brain (rather than linoleic acid) to provide long-chain polyunsaturated fatty acids and the amount of n-3 fatty acids would correlate with the desaturation activity of docosatetraenoic acid .DELTA.7-10-13-16 (22:4 n-6) to docosapentaenoic acid .DELTA.4-7-10-13-16 (22:5 n-6).