Abstract
Purpose :
Recently, it has been shown that a new class of non-dietary polyunsaturated fatty acids (C>26), the very long-chain polyunsaturated fatty acids (VLC-PUFAs), are specifically present in vertebrate retina. VLC-PUFA deficiency may be a key factor in dominant Stargardt disease 3 (STGD3), which leads to vision loss in children. We hypothesize that changes in diet influence the LC-PUFA levels in chicken egg yolk, which in turn could affect the VLC-PUFA levels in developing chicken retinas. We selected this model because of its relative procedural simplicity, larger embryonic eye size compared to rodents, and because it provides an optimal setting to study developmental changes.
Methods :
Eggs were incubated, and the embryos were dissected from embryonic development days 15 (E15) through 21 (E21) to collect developing eyes. Eyes were dissected under a light microscope to separate retina and RPE/choroid. Retina and RPE/choroid were separately extracted using a standardized method to isolate their fatty acid methyl esters, which were then analyzed by GC-MS (electron ionization mode). Analytical Method A was used to analyze the LC-PUFAs, and Method B was used to analyze C24-C36 VLC-PUFAs.
Results :
The VLC-PUFA (C28-C34) levels (%) in developing chicken retinas increase significantly from E15 (0.0108 ± 0.0007) to E21 (0.0131 ± 0.0002), while RPE/choroid is devoid of VLC-PUFAs. The retinal n-3/n-6 VLC-PUFA ratios also increased significantly from E15 (0.22 ± 0.02) to E21 (0.31±0.006). In addition, our results showed an 18% increase in retinal DHA levels and a 12% increase in n-3/n-6 LC-PUFA ratios from E15 to E21, while n-3/n-6 VLC-PUFA precursor ratios decreased by 27%.
Conclusions :
The results of this study suggest that chicken embryos could serve as a promising new model for studying VLC-PUFA synthesis in retina. In the present study, we have observed an increase in the VLC-PUFA (C28-C34) levels in the embryonic chicken retinas starting from E15 through E21. Further experiments with n-3 fatty acid enriched eggs will help us to better understand how maternal diet plays a role in altering n-3/n-6 VLC-PUFA ratios and levels in developing retina and may provide further support for the addition of omega-3 polyunsaturated fatty acids in prenatal vitamins to enhance infant ocular health.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.