Figure 8. Effect of diabetes on mRNA expression of IGF-1 associated genes. qRT-PCR analysis was performed on cDNA isolated from control and STZ-induced diabetic rat retinas after 4 and 12 weeks. Expression of each gene was normalized to acidic ribosomal phosphoprotein (P0) for each rat (A), and then scaled to the 4-week control rats for each gene (B; mean ± SEM). The 12-week diabetic rats had significantly higher IGFBP2 transcript levels than the age-matched control rats (**, p<0.01). The 4-week diabetic rats had lower IGFBP2 mRNA levels than the 4-week control rats, but the difference did not reach significance (p=0.0532). Although expression of IGFBP3 in the retina was low, the IGFBP3 transcript levels for the 4-week and 12-week diabetic rats were significantly increased over those of the age-matched control rats (*, p<0.05). Diabetes did not affect the mRNA expression levels of IGF1R or IGFBP1 at 4 or 12 weeks.