Differential composition of DHA and very-long-chain PUFAs in rod and cone photoreceptors

• Published in: Journal of lipid research Vol. 59; no. 9; pp. 1586 - 1596
• Main Authors: Agbaga, Martin-Paul, Merriman, Dana K., Brush, Richard S., Lydic, Todd A., Conley, Shannon M., Naash, Muna I., Jackson, Shelley, Woods, Amina S., Reid, Gavin E., Busik, Julia V., Anderson, Robert E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2018; The American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: Animals; docosahexaenoic acid; Docosahexaenoic Acids - chemistry; Docosahexaenoic Acids - metabolism; glycerophospholipids; Glycerophospholipids - metabolism; macular degeneration; Mice; polyunsaturated fatty acids; Retinal Cone Photoreceptor Cells - metabolism; Retinal Rod Photoreceptor Cells - metabolism; rod- and cone-dominant retinas; supraenoic lipids; rod- and cone-dominant retinas; supraenoic lipids; docosahexaenoic acid; glycerophospholipids; polyunsaturated fatty acids; macular degeneration
• ISSN: 0022-2275; 1539-7262; 1539-7262
• DOI: 10.1194/jlr.M082495

Long-chain PUFAs (LC-PUFAs; C20–C22; e.g., DHA and arachidonic acid) are highly enriched in vertebrate retina, where they are elongated to very-long-chain PUFAs (VLC-PUFAs; C ≥28) by the elongation of very-long-chain fatty acids-4 (ELOVL4) enzyme. These fatty acids play essential roles in modulating neuronal function and health. The relevance of different lipid requirements in rods and cones to disease processes, such as age-related macular degeneration, however, remains unclear. To better understand the role of LC-PUFAs and VLC-PUFAs in the retina, we investigated the lipid compositions of whole retinas or photoreceptor outer segment (OS) membranes in rodents with rod- or cone-dominant retinas. We analyzed fatty acid methyl esters and the molecular species of glycerophospholipids (phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine) by GC-MS/GC-flame ionization detection and ESI-MS/MS, respectively. We found that whole retinas and OS membranes in rod-dominant animals compared with cone-dominant animals had higher amounts of LC-PUFAs and VLC-PUFAs. Compared with those of rod-dominant animals, retinas and OS membranes from cone-dominant animals also had about 2-fold lower levels of di-DHA (22:6/22:6) molecular species of glycerophospholipids. Because PUFAs are necessary for optimal G protein-coupled receptor signaling in rods, these findings suggest that cones may not have the same lipid requirements as rods.