Docosahexaenoic acid promotes differentiation of developing photoreceptors in culture

ROTSTEIN, N.P.(AUTORA CORRESPONDIENTE); AVELDAÑO, M.I.; POLITI, L.E.

INVESTIGATIVE OPHTHALMOLOGY & VISUAL SCIENCE

ASSOC RESEARCH VISION OPHTHALMOLOGY INC

Año: 1998 vol. 39 p. 2750 - 2758

0146-0404

PURPOSE. The purpose of this work was to study the effects of diverse fatty acids on the composition, metabolism, differentiation, and characteristics of opsin expression in retina photoreceptors.METHODS. Cultures of rat retinal neurons were incubated with or without 22:6 n-3, 22:5 n-3, 20:4 n-6, 18:1 n-9, and 16:0, labeled and unlabeled.RESULTS. In photoreceptor cells incubated with 22:6 n-3 and 22:5 n-3, the proportions of thesefatty acids in phospholipids increased four- to sixfold. The remaining fatty acids did not changelipid acyl chain composition. The labeled fatty acids were all actively esterified in neuronallipids, particularly in phosphatidylcholine. Addition of unlabeled 22:6 n-3 did not affect thedistribution among lipids of the other fatty acids but displaced [3H]20:4 n-6 from phosphatidylcholine and phosphatidylethanolamine. These results suggest that retinal neurons havespecific mechanisms for processing fatty acids of different lengths and degrees of unsaturationand that 22:6 n-3 incorporation takes priority. Of all fatty acids, 22:6 n-3 was the most effectivein promoting photoreceptor differentiation. In 22:6-sufficient photoreceptors, new apicalprocesses formed, the expression of opsin augmented, and its localization improved, concentratingin the apical processes of the cells.CONCLUSIONS. The advancement in differentiation selectively elicited by 22:6 correlates with the fact that 22:6 n-3, but none of the other fatty acids, delays significantly the onset of apoptosis in photoreceptors in culture. The synthesis of 22:6-containing phospholipid molecules could berequired for the proper localization of opsin. This could contribute to furthering the differentiationof photoreceptors, preventing their apoptosis, and extending their survival.