LINOLEIC AND ALPHA-LINOLENIC ACIDS DIFFERENTLY MODIFY THE EFFECTS OF ELAIDIC ACID ON POLYUNSATURATED FATTY-ACID METABOLISM AND SOME IMMUNE INDEXES IN RATS

To explore whether the metabolic responses to trans, compared with cis , fatty acids depend on the source of dietary polyunsaturated fatty ac ids (PUFA), male Sprague-Dawley rats, 5 weeks old, were fed on diets c ontaining 30 g oleic (cis) or elaidic (trans) acids/kg in combination with either 70 g perilla oil (alpha-linolenic acid) or safflowerseed o il (linoleic acid)/kg for 3 weeks in separate experiments, The dietary fats were adjusted to have the same level of total PUFA, The dietary manipulation did not influence the growth indices, but spleen weight w as greater when the dietary PUFA source was perilla oil, The incorpora tion of trans fatty acid into liver phosphatidylcholine, phosphatidyle thanolamine, phosphatidylinositol and phosphatidylserine and adipose t issue lipids, particularly phospholipids, was significantly higher whe n rats were fed on safflowerseed oil compared with perilla oil, Howeve r, only limited differences were observed in the effects of cis and tr ans fatty acids on the proportions of PUFA in liver phospholipids. Spl enic production of prostaglandin E-2 was reduced by trans fatty acid w hen safflowerseed oil was the PUFA source, but no trans effect was obs erved on leukotriene C-4 production, Dietary PUFA significantly influe nced the concentration of plasma immunoglobulins (Ig) but the effect o f geometry was only seen in IgG which was increased by trans acid, Die tary trans fatty acid increased the CD4(+):CD8(+) T-lymphocyte ratio i n the spleen, reflecting a decreasing trend of the proportion of CD8(), when combined with perilla oil, These observations indicate that th e type of PUFA simultaneously ingested specifically influences the eff ect that trans acid exerts on PUFA metabolism, eicosanoid production a nd some immune indices.