Bioavailability and spatial distribution of fatty acids in the rat retina after dietary omega-3 supplementation

Elisa Vidal,Bokkyoo Jun,William C Gordon,Marie-Annick Maire,Lucy Martine,Stéphane Grégoire,Spiro Khoury,Stephanie Cabaret,Olivier Berdeaux,Niyazi Acar,Lionel Bretillon,Nicolas G Bazan

doi:10.1194/jlr.ra120001057

Abstract

Spatial changes of FAs in the retina in response to different dietary n-3 formulations have never been explored, although a diet rich in EPA and DHA is recommended to protect the retina against the effects of aging. In this study, Wistar rats were fed for 8 weeks with balanced diet including either EPA-containing phospholipids (PLs), EPA-containing TGs, DHA-containing PLs, or DHA-containing TGs. Qualitative changes in FA composition of plasma, erythrocytes, and retina were evaluated by gas chromatography-flame ionization detector. Following the different dietary intakes, changes to the quantity and spatial organization of PC and PE species in retina were determined by LC coupled to MS/MS and MALDI coupled to MS imaging. The omega-3 content in the lipids of plasma and erythrocytes suggests that PLs as well as TGs are good omega-3 carriers for retina. However, a significant increase in DHA content in retina was observed, especially molecular species as di-DHA-containing PC and PE, as well as an increase in very long chain PUFAs (more than 28 carbons) following PL-EPA and TG-DHA diets only. All supplemented diets triggered spatial organization changes of DHA in the photoreceptor layer around the optic nerve. Taken together, these findings suggest that dietary omega-3 supplementation can modify the content of FAs in the rat retina.

Highlights

Supplementary key words diet and dietary lipids docosahexaenoic acid eicosapentaenoic acid lipid biochemistry lipid spatial organization omega-3 fatty acids phosphatidylcholine phospholipids triglycerides very long chain polyunsaturated fatty acids
Photoreceptor cells express the elongase enzyme, elongation of very long chain FAs (ELOVL)4, which catalyzes the biosynthesis of very long chain PUFAs ( C28) including n-3 (VLC-PUFAs, n-3) from 26:6 FAs derived from DHA or EPA; EPA is the preferred substrate
Among the factors affecting n-3 LC-PUFA incorporation is the dietary intake of linoleic acid (LA; 18:2, n-6) from the n-6 series because the incorporation of n-3 LC-PUFA is inversely associated with the intake of LA, in the retina [25]

Summary

Introduction

High dietary intake of omega-3 (n-3) long chain (LC)-PUFAs (C18–22) is associated with a lower risk of developing AMD [3]. Some Western countries have raised dietary recommendations for EPA and DHA intake to 500 mg/day to reduce the risk of developing AMD [23]. The efficacy of EPA compared with DHA intake to increase the incorporation of DHA in the retina has not been studied. The present study aims to define the efficacy of different dietary formulations of TGs and/or PLs with EPA and DHA for their incorporation in plasma, erythrocytes, retinal pigment epithelial (RPE) cells, and retina in the rat. Our aim was to determine, using MALDI-imaging MS (MALDI-IMS), whether dietary supplementation with omega-3 FAs altered the cellular spatial distribution of FAs in the rat retina between photoreceptors and RPE cells

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Conclusion