Dietary ALA, EPA and DHA have distinct effects on oxylipin profiles in female and male rat kidney, liver and serum

Abstract

There is much data on the effects of dietary n-3 fatty acids on tissue fatty acid compositions, but comparable comprehensive data on their oxygenated metabolites (oxylipins) is limited. The effects of providing female and male rats with diets high in α-linolenic acid (ALA), EPA or DHA for 6 weeks on oxylipins and fatty acids in kidney, liver and serum were therefore examined. The oxylipin profile generally reflected fatty acids, but it also revealed unique effects of individual n-3 fatty acids that were not apparent from fatty acid data alone. Dietary ALA increased renal and serum DHA oxylipins even though DHA itself did not increase, while dietary EPA did not increase DHA oxylipins in kidney or liver, suggesting that high EPA may inhibit this conversion. Oxylipin data generally corroborated fatty acid data that indicated that DHA can be retroconverted to EPA and that further retroconversion to ALA is limited. Dietary n-3 fatty acids decreased n-6 fatty acids and their oxylipins (except linoleic acid and its oxylipins), in order of effectiveness of DHA > EPA > ALA, with some exceptions: several arachidonic acid oxylipins modified at carbon 15 were not lower in all three sites, and EPA had a greater effect on 12-hydroxy-eicosatetraenoic acid and its metabolites in the liver. Oxylipins were predominantly higher in males, which was not reflective of fatty acids. Tissue-specific oxylipin profiles, therefore, provide further information on individual dietary n-3 fatty acid and sex effects that may help explain their unique physiological effects and have implications for dietary recommendations.