Neural 22-carbon fatty acids in the weanling rat respond rapidly and specifically to a range of dietary linoleic to alpha-linolenic fatty acid ratios.
Changing the dietary ratio of the essential fatty acids (EFA), 18:2n6 and 18:3n3, while keeping the amounts of other fatty acids in the diet constant can rapidly and specifically alter the proportions of n6 and n3 22-carbon fatty acids in the brain of the weanling rat. A dietary 18:2n6/18:3n3 ratio of 165 versus 1.8 caused higher n6 and lower n3 22-carbon fatty acid levels, without changing total 22-carbon fatty acid levels, in phosphatidylethanolamine and phosphatidylcholine from several neural membrane fractions. This was apparent after only 2 weeks and showed no sign of plateauing after 12 weeks. Other neural fatty acids were essentially unaffected. The three most abundant 22-carbon fatty acids responded somewhat differently to increments in the dietary 18:2n6/18:3n3 ratio (1.8, 9, 36, and 165). Levels of 22:4n6 increased by similar absolute amounts for each four-fold increase in dietary 18:2n6/18:3n3 ratio; in contrast, the largest absolute changes in 22:5n6 and 22:6n3 levels occurred as the 18:2n6/18:3n3 ratio increased from 36 to 165. This study shows that the 18:2n6/18:3n3 ratio of diets high in fat (40% of energy) and adequate in EFA, both typical of diets in developed countries, can substantially and relatively quickly affect the 22-carbon fatty acids in the brain, even after the rapid accumulation of these fatty acids during neural growth has ceased.
Dyer
J R
JR
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.
Greenwood
C E
CE
D000818:Animals; D002244:Carbon; D004041:Dietary Fats / Q000494:pharmacology*; D005227:Fatty Acids / Q000737:chemistry / Q000378:metabolism*; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000494:pharmacology*; D008042:Linolenic Acids / Q000494:pharmacology*; D008297:Male; D009420:Nervous System / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors; D014886:Weaning; D017962:alpha-Linolenic Acid
D004041:Dietary Fats; D005227:Fatty Acids; D008041:Linoleic Acids; D008042:Linolenic Acids; D017962:alpha-Linolenic Acid; D002244:Carbon; D019787:Linoleic Acid