Comprehensive and sensitive quantification of long-chain and very long-chain polyunsaturated fatty acids in small samples of human and mouse retina.
Fatty acids (FAs), including long-chain and very long-chain polyunsaturated fatty acids (LC-PUFAs, C12-22; VLC-PUFAs, C24-38), play an important role in retinal function and health. Deficiencies in LC-PUFAs and VLC-PUFAs, as well as mutations in the enzyme responsible for elongation of very long-chain fatty acids (ELOVL4), have been associated with macular dystrophies and degenerations. Published analytical methods, including high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS) and gas chromatography-MS (GC-MS), can quantify VLC-PUFAs but require at least an entire human retina which limits the ability to understand physiologically relevant variations in lipids that can occur at a regional level within the retina. Until now, quantification of VLC-PUFAs in just the human macula, the cone-rich region of the central retina responsible for high acuity vision, has not been feasible due to its small size (4-5mm in diameter). In this study, we have developed a sensitive GC-MS method using newer generation enhanced GC-MS detector sensitivity which for the first time quantifies not only 14 VLC-PUFAs and 26 LC-FAs but also n-3/n-6 ratios of PUFAs in 4mm punches of human retina or a single pair of mouse retinas. Our results showed that saturated LC-FAs are higher in the human peripheral retina than in the macula, while unsaturated LC-FAs are higher in the macula than in the peripheral retina. On the other hand, the VLC-PUFAs are higher in the peripheral retina compared to macula. There is no difference in n-3/n-6 ratios of PUFAs observed between human macula and peripheral retina, while mouse retina has almost ten times more VLC-PUFAs than human macula and peripheral retina (2.27% versus 0.25% and 0.32%, respectively) and much higher n-3/n-6 ratios compared to human retina (9:1 versus ∼0.9:1). This high sensitivity analytical technique provides a valuable new tool for studies on the role of FAs in the pathological processes of macular degenerations and dystrophies.
Department of Ophthalmology and Visual Sciences, Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA.
Aihua
A
Liu
Ryan
R
Terry
Yanhua
Y
Lin
Kelly
K
Nelson
Paul S
PS
Bernstein
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D005231:Fatty Acids, Unsaturated / Q000032:analysis* / Q000737:chemistry; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D016014:Linear Models; D008297:Male; D051379:Mice; D008875:Middle Aged; D015203:Reproducibility of Results; D012160:Retina / Q000737:chemistry*; D012680:Sensitivity and Specificity
D005231:Fatty Acids, Unsaturated
GC–MS; Human macula; Long-chain fatty acids (LC-FAs); Mouse retina; Very long-chain polyunsaturated fatty acids (VLC-PUFAs)