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H S Weisinger, A J Vingrys, B V Bui, A J Sinclair; Effects of dietary n-3 fatty acid deficiency and repletion in the guinea pig retina.. Invest. Ophthalmol. Vis. Sci. 1999;40(2):327-338.
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PURPOSE: To investigate the nature and reversibility of biochemical and functional changes in the retina encountered over a single generation of dietary n-3 polyunsaturated fatty acid deficiency in guinea pigs. METHODS: Dunkin-Hartley guinea pigs were fed for 16 weeks after weaning with diets supplemented with safflower seed oil (n-3 deficient) or canola oil (n-3 sufficient, control). A number of deficient animals were repleted at 6 weeks with canola oil for 5 or 10 weeks, or at 11 weeks for 5 weeks. Electroretinograms (0.8 and 4.3 log scot td x sec) were collected at 6, 11, and 16 weeks after weaning. Conventional waveforms (a- and b-waves), oscillatory potentials, and receptoral and postreceptoral subcomponents (PIII and PII, respectively) were evaluated. Cone pathway function was assessed with 30-Hz flicker at the brighter intensity. Retinal phospholipid fatty acids were measured by capillary gas-liquid chromatography. RESULTS: Electroretinographic amplitudes showed statistically significant losses in b- and a-waves after 6 and 16 weeks of dietary n-3 deficiency, respectively. The response amplitude to 30-Hz flicker was reduced 42% after 16 weeks. Retinal docosahexaenoic acid (DHA) levels of animals maintained on the safflower oil diet for 16 weeks were 42% of levels in age-matched control subjects. There were significant losses in maximum response amplitudes (R(mPIII) and R(mPII)), although the major effect was a reduction in sensitivity of the receptoral response. Complete functional recovery was observed only in animals repleted for 10 weeks. CONCLUSIONS: Functional deficits in PIII and PII of the electroretinogram were apparent in first-generation guinea pigs fed an n-3 deficient diet. These losses showed a correlation with age and retinal DHA level, although varying degrees of dependence on the DHA level were found. All functional deficits were reversed after 10 weeks of dietary n-3 repletion. The results suggest that DHA may serve several functional and structural roles in the retina and further emphasize the requirement for DHA in the normal development of vision.
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