Effect of dietary fish oil on acute light-induced photoreceptor damage in the rat retina

• Published in: Investigative ophthalmology & visual science Vol. 35; no. 1; pp. 78 - 90
• Main Authors: Reme, CE, Malnoe, A, Jung, HH, Wei, Q, Munz, K
• Format: Journal Article
• Language: English
• Published: Rockville, MD ARVO 01-01-1994; Association for Research in Vision and Ophtalmology
• Subjects: Acute Disease; Animals; Biological and medical sciences; Diet; Fatty Acids - metabolism; Fish Oils - administration & dosage; Injuries of the orbit. Foreign bodies of the eye. Diseases due to physical agents; Light - adverse effects; Lipid Peroxides - metabolism; Liver - metabolism; Male; Medical sciences; Phospholipids - metabolism; Photoreceptor Cells - pathology; Photoreceptor Cells - radiation effects; Radiation Injuries, Experimental - metabolism; Radiation Injuries, Experimental - pathology; Radiation Injuries, Experimental - prevention & control; Rats; Rats, Sprague-Dawley; Retina - metabolism; Retina - pathology; Retina - radiation effects; Rhodopsin - metabolism; Soybean Oil - administration & dosage; Traumas. Diseases due to physical agents; Vitamin E - metabolism; Performance evaluation; Photosensitivity; Retinopathy; Rat; Acute; Rodentia; Photoreceptor; Polyunsaturated fatty acid; Lipids; Retina; Supplemented diet; Fish oil; Eye disease; Vertebrata; Experimental disease; Mammalia; Diet; Animal; Phototoxicity; Peroxidation
• ISSN: 0146-0404; 1552-5783

Previous studies have shown that ingestion of fish oil (FO) containing a high proportion of n-3 polyunsaturated fatty acids increases the susceptibility of cellular membranes to oxidative damage in various tissues. In the retina, lipid peroxidation is thought to be a major mechanism contributing to light-induced lesions. Therefore, we investigated the effect of FO on acute light-induced photoreceptor damage.
For 2 months, weanling rats were fed diets containing either soybean oil (SOY) or FO as main lipid component.
Rats fed FO had significantly higher levels of eicosapentaenoic acid (EPA, 20:5n-3) and higher ratios of EPA to arachidonic acid (AA, 20:4n-6) in retinal phospholipids and diacylglycerols than rats fed SOY. The levels of docosahexaenoic acid (DHA, 22:6n-3) were similar in both dietary groups. The susceptibility to lipid peroxidation was enhanced in the isolated retina of FO-fed rats as shown by higher levels of thiobarbituric acid reactive substances after incubation of retinal membranes with Fe2+/ascorbate. The retinal content of alpha-tocopherol was similar in SOY- and FO-fed animals. Light damage consisting of acute rod outer segment (ROS) disruptions was induced by exposing dark-adapted animals to 600 to 700 lux (230 to 260 microW/cm2) of white fluorescent light for 30 minutes. Damage was quantitated using a computerized multifunctional image analysis of retinal thin sections. Although structural alterations of the ROS were present in both groups, FO-fed rats showed less damage at the base of the ROS. This occurred in spite of higher rhodopsin levels in FO-fed rats. There was no effect of diet on retinal morphology in dark-adapted rats.
These results indicate that FO does not enhance the susceptibility to acute ROS disk disruptions in the rat retina. Our study further suggests that FO exerts a partial protective effect that may be related to changes in the formation of lipid mediators derived from EPA and AA in retinal phospholipids.