EFFECTS OF VITAMIN-E ON THE RETINA AND RETINAL-PIGMENT EPITHELIUM OF IRCS RATS

A recessive gene defect leads to gradual loss of photoreceptor cells i n the retinas of a rat strain developed by the Royal College of Surgeo ns (RCS). Previous evidence suggested that retinal degeneration in RCS rats is partly due to instability of the lysosomal membranes of the r etinal pigment epithelium (RPE). Lipid peroxidation contributes to ins tability of lysosomal membranes. Tn this study, administration of the antioxidant vitamin E retarded the degenerative process in RCS rat ret inas as evidenced by light- and transmission-electron microscopic exam ination. Photoreceptor cells as well as the RPE were in better conditi on in animals treated with 100 or 150 mg vitamin E/kg body weight dail y than in untreated animals or animals treated with fewer doses. This assertion is based on the increased survival of photoreceptor cell nuc lei as evidenced by the thickness of the outer nuclear layer coupled w ith a reduction in the number of pycnotic nuclei, the conservation of the outer limiting membrane, and the presence of phagosome-like struct ures in the RPE. These and previous results in this strain of rats lea d us to propose that lipid peroxidation plays an important role in the pathogenesis of this degenerative process of the retina.