Effects of antioxidant nutrient deficiency on the retina and retinal pigment epithelium of albino rats: a light and electron microscopic study

Male Sprague-Dawley rats were maintained, from weaning, on diets deficient either in vitamin E, selenium, chromium and sulfur amino acids (?E?Se?S?Cr), or only in vitamin E and selenium (?E?Se+S+Cr). Control animals (+E+Se+S+Cr) received all four nutrients. After 24–26 weeks on their respective diets, both deficient groups showed a dramatic accumulation of an autofluorescent pigment, similar to lipofuscin, in the retinal pigment epithelium. This increased autofluorescence was correlated with a large increase in the number of electron-dense inclusion bodies observed in the pigment epithelium by transmission electron microscopy. Accompanying the build-up of autofluorescent pigment was the development of an irregularity and an overall increase in retinal pigment epithelium cell height. There was also an increase in the number of lipid droplets in the retinal pigment epithelium, particularly in the periphery of the eye. In the eyes of deficient animals, cells were occasionally seen which appeared to have detached from Bruch's membrane and migrated into the region of the photoreceptor outer segments. Photoreceptor outer segment phagocytosis by the retinal pigment epithelium appeared to be decreased as a consequence of dietary antioxidant deficiency, since a reduction of over 75% in the number of phagosomes per unit retinal pigment epithelium cell length was seen in some areas of the eye in both deficient groups.These changes in the retinal pigment epithelium were accompanied by a pronounced loss of photoreceptor cells, particularly from the central retina (20–34% fewer cells than supplemented controls). The disk membranes of the photoreceptor outer segments of deficient animals were often swollen, disoriented and vesiculated, and areas were frequently seen where outer segment debris had accumulated at the interface between the photoreceptors and retinal pigment epithelium.Many of the changes in the retina and retinal pigment epithelium were more severe in the fully deficient (?E?Se?S?Cr) group, than in the group deficient only in vitamin E and selenium.