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.
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.
J R
JR
Dyer
C E
CE
Greenwood
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