Location: Immunity and Disease Prevention ResearchTitle: Docosahexaenoic acid and eicosapentaenoic acid did not alter trans-10,cis-12 conjugated linoleic acid incorporation into mice brain and eye lipids
Submitted to: Lipids Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2017
Publication Date: 8/4/2017
Citation: Vemuri, M., Adkins, Y.C., Mackey, B.E., Kelley, D.S. 2017. Docosahexaenoic acid and eicosapentaenoic acid did not alter trans-10,cis-12 conjugated linoleic acid incorporation into mice brain and eye lipids. Lipids Journal. 52(9):763-769. https://doi.org/10.1007/s11745-017-4282-x.
Interpretive Summary: Increased intake of trans fatty acids increases the incidence of several chronic human diseases including diabetes, cardiovascular and nonalcoholic fatty liver diseases (NAFLD). Conjugated linoleic acid (t10, c12-CLA) CLA is one of the major trans fatty acids found in processed foods and partially hydrogenated vegetable oils; it has been found to cause insulin resistance and NAFLD in animal models. We have previously reported that dietary CLA was incorporated into tissue lipids including liver, heart, and adipose tissue and decreased the concentrations of n3 polyunsaturated fatty acids (PUFA) and the n3:n6 ratio in these tissues. Incorporation of t10, c12-CLA into tissue lipids, its adverse effects and the prevention of those effects by n3 PUFA have been well established in non-neural tissues (liver, adipose, muscle, heart, and others). However, incorporation of CLA into neural (brain and eye) tissue lipids, its effects on fatty acid composition and potential adverse effects and their prevention by n3 PUFA have not been documented. Therefore, the purpose of this study was to determine whether feeding diets containing t10, c12-CLA would result in its incorporation into brain and eye lipids, alter their fatty acid composition, and to compare the efficacies of DHA and EPA in preventing the CLA induced changes in tissue fatty acids when fed concomitantly. Four groups of 8 week old female mice were fed experimental diets (Control, 0.5% (w/w) CLA, 0.5% CLA + 1.5% DHA, or 0.5% CLA + 1.5% EPA, for 56 days before the tissues were collected for fatty acid analysis. When compared with the control group CLA concentration was significantly (P<0.05) greater in the eye but not in the brain lipids of the CLA group. Compared with our previously published findings from the same study, the increase in eye CLA concentration was relatively much lower than that in liver and adipose tissue. The sums of saturated, monounsaturated, polyunsaturated fatty acids, and n3:n6 ratio did not differ between the control and CLA in both brain and eye lipids. The n3:n6 ratio and concentrations of 20:5n3 and 22:5n3 were significantly greater, and those of 20:4n6, 22:4n6, and 22:5n6 were lesser in the CLA+DHA and CLA+EPA groups than in the control and CLA groups for both tissues. DHA concentration was higher only in the CLA+DHA group but not in the CLA+EPA group when compared with the CLA group for both tissues. These findings suggest that compared with the non-neural tissues, brain and eye are relatively protected from the adverse effects of CLA. The two n-3 PUFA, DHA and EPA generally caused similar changes in the brain and eye fatty acids, except that DHA concentration was greater only in the DHA group and not in the EPA group when compared with the control and CLA groups.
Technical Abstract: Trans 10,cis 12-CLA has been reported to alter fatty acid composition in several non-neurological tissues, but its effects are less known in neurological tissues. Therefore, the purpose of this study was to determine if CLA supplementation would alter brain and eye fatty acid composition and if those changes could be prevented by concomitant supplementation with docosahexaenoic acid (DHA; 22:6n3) or eicosapentaenoic acid (EPA; 20:5n3). Eight-week-old, pathogen-free C57BL/6N female mice (n = 6/group) were fed either the control diet or diets containing 0.5% (w/w) t10,c12-CLA in the presence or absence of either 1.5% DHA or 1.5% EPA for 8 weeks. CLA concentration was significantly (P < 0.05) greater in the eye but not in the brain lipids of the CLA group when compared with the control group. The sums of saturated, monounsaturated, polyunsaturated fatty acids, and n3:n6 ratio did not differ between these two groups for both tissues. The n3:n6 ratio and concentrations of 20:5n3 and 22:5n3 were significantly greater, and those of 20:4n6, 22:4n6, and 22:5n6 were lesser in the CLA + DHA and CLA + EPA groups than in the control and CLA groups for either tissue. DHA concentration was higher in the CLA + DHA group only but not in the CLA + EPA group when compared with the CLA group for both tissues. The dietary fatty acids generally induced similar changes in brain and eye fatty acid concentration and at the concentrations used both DHA and EPA fed individually with CLA were more potent than CLA alone in altering the tissue fatty acid concentration.