The broad, long-term objective is to understand how retina can adapt itself to environmental light changes to protect photoreceptor cells from degeneration and to elucidate the mechanism whereby this adaptation system is triggered, and eventually, to manipulate this system to increase photoreceptor cell resistance to the degeneration. The focus of this research proposal is to characterize the genes and protein expression as a function of retinal adaptation in response to bright cyclic light, and to understand how this adaptation protects photoreceptors from degeneration. To achieve this goal, the gene and protein expressions of bFGF, aFGF, FGF receptor-1, CNTF, CNTF receptor- alpha, BDNF, trk B, IGF-1 and IGF-1 receptor, as well as proto-oncogene bcl-2 will be quantitatively characterized by performing Northern and Western blot analysis. Afterward, in situ hybridization and immunocytochemistry will be performed to localize the expression. In addition, such adaptation system in adult rat retina triggered by bright cyclic light to protect photoreceptors from degeneration will also be examined.