Normal Aging Involves Modulation of Specific Inflammatory Markers in the Rat Retina and Choroid

Recent work has suggested that inflammation is a common component of a number of age-related diseases. The hypothesis of the present study was that normal aging of the retina and choroid would increase levels of inducible nitric oxide synthase (iNOS), prostaglandin E2 (PGE2), and tumor necrosis factor alpha (TNF-alpha). To investigate this hypothesis, gene expression and protein analyses were completed on retinal and choroidal samples from Fischer 344 x Brown Norway F1 hybrid rats at 8, 22, and 32 months of age. Aging of the choroid produced significant increases in PGE2, with decreased TNF-alpha protein. Protein levels and messenger RNA of iNOS and TNF-alpha protein levels were significantly decreased in the aging retina in contrast to PGE2 protein activity, which was increased with age in the retina. These results suggest that PGE2 is likely involved in the aging process in both the retina and choroid, whereas iNOS plays a role predominantly in the retina.