Polyunsaturated fatty acids in tissues of rats fed trielaidin and high or low levels of linolenic acid.

Male and female weanling rats that were born to dams fed a diet low in linolenic acid received diets of 15% lipids by weight containing 45% elaidic acid (as trielaidin) and 8.5% or 0.1% linolenic acid for 10 weeks. Four other groups, in which palmitic or oleic acid replaced elaidic acid in the diet, served as controls. The fatty acid profiles of several lipid classes were determined in adipose tissue, adrenals, testes, heart and brain. Elaidic acid was incorporated into tissue lipids in varying degrees, depending on the organ and on the lipid class. Feeding elaidic acid induced no changes in the polyunsaturated fatty acid (PUFA) profiles of testes lipids but resulted in definite modifications of the PUFA patterns of heart phosphatidylcholine (PC) and phosphatidylethanolamine (PE). In linolenic acid-deprived rats, arachidonic acid was decreased in PC and linoleic acid was increased in both PC and PE; 22:5n-6 was strongly depressed in both PC and PE. In linolenic acid-fed rats, 22:6n-3 was decreased in PC and PE. These changes, on the whole, were more evident in females, and some also were observed in adrenal cholesteryl esters but only slightly in brain phospholipids. The apparent inhibition of the biosynthesis of PUFA induced by dietary elaidic acid appeared to be complex and of greater intensity in the n-6 fatty acid series than in their n-3 homologues.