Abstract
Purpose: :
Deficiency of long-chain polyunsaturated fatty acids (LC-PUFAs, 12<Cn<24) and very LC-PUFAs (VLC-PUFAs, Cn≥24), and an imbalance of n-3/n-6 PUFA ratios occur in retinas with macular degenerations. While VLC-PUFAs are not present in the normal human diet, LC-PUFAs, including the precursors of VLC-PUFAs such as eicosapentaenoic acid (EPA, n-3) and arachidonic acid (AA, n-6) are abundant. The average dietary fat intake in the previous weeks, months, and years can be reflected by human serum, red blood cell (RBC) lipids, and adipose tissue, respectively. Thus, we aimed to develop a sensitive gas chromatography-mass spectroscopy (GC-MS) method to examine if biomarkers of dietary fat intake can influence retinal n-3/n-6 LC- and VLC-PUFA ratios.
Methods: :
We collected 29 normal human donor eyes (age=68.1±13.5 yrs) to get 4 mm punches of peripheral retina along with samples of orbital adipose tissue, RBCs and serum. After being homogenized, extracted and then purified, samples were analyzed by a highly sensitive DSQII GC-MS under electron impact mode on an Rxi-5MS column.
Results: :
The optimized method can detect VLC-PUFAs in 4 mm punches of peripheral retina. LC-PUFAs were also measured in orbital adipose tissue, RBCs and serum. The ratios of EPA to AA (n-3/n-6) in adipose tissue and RBCs were significantly correlated the n-3/n-6 VLC-PUFA ratios in human retina.
Conclusions: :
We have successfully developed a GC-MS method with improved sensitivity which can detect VLC-PUFAs in very tiny amounts of tissue. Our findings revealed that human diet (EPA/AA) can influences human retinal n-3/n-6 VLC-PUFA ratios, which may explain why a diet high in omega-3 rich fish oil (DHA and EPA) is beneficial against macular degeneration in many epidemiologic studies.
Keywords: lipids • macula/fovea