Figure 1. Changes in RPE NAD+ metabolism with aging in mice. RPE/eye cup was dissected from 2, 12 and 18 months old male C57BL/6J mice to evaluate changes in NAD+ metabolism. (A) NAD+ content was measured using a commercially available kit. (B) Overview of NAD synthesis pathways in mammals. (C-E) Changes in mRNA expression of enzymes regulating NAD+ synthesis were performed by qPCR. (F) Changes in SIRT-1 protein levels were measured by western blotting. Data is presented as mean ± S.E.M for n=5. A representative western blot image from three replicates is shown. mRNA expression of genes were normalized to 18s expression. *p<0.05 compared to 2M (two months old mice). NAMPT; Nicotinamide phosphoribosyltransferase, QPRT; Quinolinate Phosphoribosyltransferase, NMNAT; Nicotinamide mononucleotide adenylyltransferease.