Radial distribution of tocopherols in rhesus monkey retina and retinal pigment epithelium-choroid.
OBJECTIVE
To map vitamin E as a function of distance from the foveal center in the primate retina and retinal pigment epithelium (RPE)-choroid.


METHODS
Eyecups from rhesus monkeys were dissected with circular trephines so that the innermost disc, centered on the fovea, was in the center of a series of concentric rings. Two different types of dissection were performed. For one type, the authors used circular trephines with diameters of 1, 4, 8, and 10 mm (1,4-D), whereas for the other type the diameters were 2, 5, 8, and sometimes 10 mm (2,5-D). When possible, the neural retina was separated from the RPE-choroid. Tissues were analyzed for vitamin E, retinyl palmitate, and protein.


RESULTS
Surface area, volume, and protein were used as indexes of the amount of tissue analyzed. Distributions of vitamin E in neural retina were dependent on the tissue metric used and type of dissection performed. However, regardless of the tissue metric used, the central 1-mm disc of the 1,4-D was, on average, higher in vitamin E content than was the central 2-mm disc of the 2,5-D. This was particularly true when volume was the tissue metric. From the average values of vitamin E in a series of concentric discs, a composite plot of the vitamin E concentration in the neural retina was generated that took into consideration both types of dissection. That plot displayed a local maximum in the fovea and then precipitously declined to a minimum in the region between 0.5 and 1.0 mm eccentricity (near the foveal crest); at greater eccentricities, the vitamin E concentration rose to a value similar to that in the fovea, i.e., the composite plot indicated that vitamin E has a V-shaped distribution in the central neural retina. Vitamin E distribution in the RPE-choroid, with surface area as the tissue metric, also was measured. For this tissue, the foveal region displayed a local maximum.


CONCLUSIONS
By combining the results of two different types of dissection, the authors found that in the neural retina, vitamin E displayed a minimum near the foveal crest. This minimum correlated anatomically with the site at which areolar (geographic) atrophy frequently occurs in retinal pigment epithelial cells in the human disease, age-related macular degeneration.
Crabtree
D V
DV
Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA.
Adler
A J
AJ
Snodderly
D M
DM
D000818:Animals; D002829:Choroid / Q000166:cytology / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005584:Fovea Centralis; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000378:metabolism*; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D014018:Tissue Distribution; D014810:Vitamin E / Q000378:metabolism*
D014810:Vitamin E