Action of Linolenic and Docosahexaenoic Acids upon the Eicosatrienoic Acid Level in Rat Lipids

Abstract

Weanling rats were fed a fat-free diet, and a fat-free diet supplemented with 4-deoxypyridoxine-HCl. The fatty acid composition of the lipids of heart, liver, epididymal fat, liver phospholipids and triglycerides were analyzed after feeding linoleate, linolenate and docosahexaenoate. The structure of octadecadienoate, eicosatrienoate and eicosatetraenoate was recognized by reductive ozonolysis. The levels of eicosa-5,8,11-trienoate were markedly lowered either by linoleate, linolenate or docosahexaenoate, thus showing a reduced conversion of oleate into eicosa-5,8,11-trienoate. Docosahexaenoate was readily incorporated into the phospholipids and appeared to be a direct regulator of eicosa-5,8,11-trienoic level, whereas linolenate was very slightly incorporated and appeared to produce, at least partially, the same effect through its conversion into docosahexaenoate. This phenomenon is thought to be related not only to a competition in the desaturating and elongating step of oleic, linoleic and linolenic acids, but also to phospholipid synthesis.