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C. P. Smith, J. J. Steinle; Changes in Growth Factor Expression in Normal Aging Rat Retina. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3050.
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To determine whether aging affects growth factor expression or expression of their receptors in the rat retina.
Male F344xBN F1 rats were euthanized and the eyes enucleated at 8, 22, and 32 months of age. Real time PCR and western blot analysis was conducted to investigate changes in steady state mRNA expression and protein levels for VEGF, KDR, PEDF, Ang-1, Tie-2, EphB4 and ephrinB2 in the aging retina of rats.
A significant increase of VEGF protein levels was found at 32 months compared to 8 and 22 months although mRNA expression did not change. Although steady state mRNA expression did not change, protein expression of KDR was found to be increased at 22 months compared to 8 months. Tie-2 protein levels were significantly decreased at 32 months of age compared to 8 months, whereas steady state mRNA was significantly increased by 32 months. Protein levels of ephrinB2 were found to be significantly lower at both 22 and 32 months compared to 8 months of age, while steady state mRNA expression also decreased by 32 months of age. No significant changes in protein levels were found for PEDF, Ang-1 or EphB4.
Increases found in VEGF and KDR protein expression suggest that there is an increase of VEGF receptor and one of its ligand with normal aging of the retina. The decreases found in Tie-2 and ephrinB2 protein expression suggest that while VEGF and its receptors are being upregulated, the latter stages of angiogenesis such as vessel stabilization are not yet initiated.
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