Abstract
Purpose :
We have shown that retinas of adiponectin receptor 1 (AdipoR1) knockout (KO) mice and membrane frizzled-related protein (MFRP) KO mice have reduced docosahexaenoic acid (DHA) and very-long-chain polyunsaturated fatty acids (VLC-PUFAs) contained in phoshatidylcholine (PC) molecular species. This led to retina degeneration. DHA is enriched in retina, and AdipoR1 and MFRP are involved in DHA uptake/retention in the retina, so we asked if molecular distribution of fatty acids in phosphatidylethanolamine (PE) follows a similar behavior. We also asked if PC and PE molecular species are affected by AdipoR1 KO and MFRP KO in a retina-specific fashion.
Methods :
Lipids were extracted from retinas, brains, kidneys, livers and hearts from AdipoR1 KO, MFRP KO, and control mice. Liquid chromatography tandem mass spectrometry (LC-MS/MS) was used for the measurement of PC and PE molecular species. Naturally-occurring isotope correction was done using self-made programs before distribution of PC and PE was calculated.
Results :
In retina, both AdipoR1 KO and MFRP KO showed reduction of DHA-containing PC and PE, especially PC(44:12) and PE(44:12), which contain DHA for both sn1 and sn2. VLC-PUFAs (ranging from 32 to 38 carbons) occurred only in PCs. Arachidonic acid(AA)-containing PC and PE (PC(36:4),PE(38:4)) increased in the KO retinas, indicating AA replaced DHA in PC and PE. However, other organs did not show any differences among the groups.
Conclusions :
The reduction of DHA and VLC-PUFAs in AdipoR1 KO or MFRP KO in PC and PE molecular species is retina-specific. Even though AdipoR1 is expressed in other organs, including kidney, liver and brain, DHA uptake/retention in those organs was not affected by AdipoR1/MFRP ablation.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.