RETINYL PALMITATE IN MACAQUE RETINA RETINAL-PIGMENT EPITHELIUM-CHOROID - DISTRIBUTION AND CORRELATION WITH AGE AND VITAMIN-E

Retinyl palmitate (RP) and retinyl stearate (RS) are of central import ance in the visual cycle because they are the major storage molecules for retinol. In some tissues (e.g. liver) the amount of vitamin A (mos tly in the form of retinyl ester) is positively correlated with both t he amount of alpha-tocopherol (alpha-T) and age. Furthermore, alpha-T is a noncompetitive inhibitor of the hydrolysis of RP. We measured RP, RS, alpha-T and beta + gamma-tocopherol (beta + gamma - T) as functio ns of distance from the foveal center (eccentricity) in the retina-RPE -choroid (NRC) of rhesus monkeys using high-pressure liquid chromatogr aphy. It was found that the central and peripheral NRC differed with r espect to these parameters. The concentration (pmoles sq mm(-1)) of RP was higher in the central NRC than in the peripheral NRC and was at a maximum in the region of the fovea. Furthermore, although in the peri pheral NRC, RP was well correlated with age and alpha-T (similar to ot her tissues), in the central NRC, RP per so mm was more clearly relate d to photoreceptor density. These differences imply that the central N RC controls the concentration of RP within it, while the concentration of RP in the peripheral NRC is determined by its environment (e.g. nu trients available from blood) and the age of the individual. (C) 1997 Academic Press Limited.