The influence oftrans‐acids on desaturation and elongation of fatty acids in developing brain

Abstract

trans-Monounsaturated acids account for up to 3% of the total octadecenoic acyl chains of human brain lipids. To investigate the influence of trans-acids on desaturation and chain elongation of fatty acids, in vitro and in vivo experiments with rat brain were performed. In the in vitro assays of delta 9 desaturation, delta 6 desaturation and chain elongation, trans,trans-dienoic acid was inhibitory, particularly to chain elongation. Slight differences between the inhibitory effects of trans-monoenoic acids and their cis-isomers were observed. In an in vivo model, unlabeled fatty acid (stearate, oleate, elaidate, linoleate, linoelaidate, arachidonate, or trans-monoene from margarine) was injected simultaneously with [1-14C] linoleic acid into the brains of suckling rats. Linoelaidate and oleate inhibited desaturation and elongation of linoleate, whereas elaidate, stearate and trans-monoene from margarine were stimulatory. While the demonstration of differences between cis and trans monenic isomers required relatively high levels of the test acids, it appears that trans-acids can influence desaturation and elongation enzymes that lead to acyl chain modification in the central nervous system.

Metabolism of trans fatty acid isomers

“…Much smaller effects were observed in comparable experiments when elaidic acid per se was fed, suggesting that other trans isomers may have a greater influence on desaturation in vivo (Astorg & Chevalier, 1988). In experiments in which particular fatty acids were injected into rat brain, oleate strongly inhibited desaturation and elongation of linoleate, while elaidate, and a trans-monoene from margarine were stimulatory (Cook, 1981). However, the effects may be dependent on the levels of linoleate in the diet, and Zevenbergen et al (1988), for example, found small effects only of dietary trans monoenoic fatty acids on mitochondrial fatty acid composition when higher levels of linoleate were fed.…”

“…For example, these include liver microsomes , cultured glioma cells (Cook & Emken, 1990), brain homogenates (Cook, 1981), bovine endothelial cells (Loi et al, 2000) and perfused rat liver (Bretillon et al, 1998a).…”

“…The Δ6 desaturation of 18:2 isomers in vitro has been studied by Cook (1981) and Berdeaux et al (1998), using liver microsomes, and by Bretillon et al (1998a) using a perfused liver model. Studies on microsomes showed that the 9c,12t-18:2 isomer was a much better substrate for desaturase than the 9t,12c isomer.…”

Essential Fatty Acids - A Review

“…Activities of 6 and 5 desaturases are decreased in diabetes mellitus, hypertension, hyperlipidemia, and metabolic syndrome X. Trans fats interfere with the metabolism of EFAs and promote inflammation, atherosclerosis and coronary heart disease [1,11]. The pro-inflammatory action of trans fats is due to their ability to interfere with EFA metabolism.…”

Inverse association between trans isomeric and long-chain polyunsaturated fatty acids in cord blood lipids of full-term infants

“…In addition, the ability of trans fatty acids to interfere with essential fatty acid metabolism (8,9) may be of practical importance in pediatrics. Evidence of this interference in humans includes significant inverse correlations between plasma values of trans isomeric and long-chain polyunsaturated fatty acids, both in preterm infants (10) and in healthy children aged 1-15 y (11).…”