The Development of Diabetic Retinopathy in Goto-Kakizaki Rat and the Expression of Angiogenesis-Related Signals.

The Goto-Kakizaki (GK) rat is a genetic model of type 2 diabetes. Diabetic retinopathy (DR) is a common complication of diabetes. In this study, we observed the development of DR in GK rats and the expression of some angiogenesis-related signals. GK rats were housed for 5, 6 and 7 months. Results of retinal vessels stained by cluster of differentiation 31 (CD31) showed that the number of retinal vessels was increased in GK rats at both 6 and 7 months. Retinal histological observation also evidenced such increase. Retinal mRNA expression of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), VEGFB and its receptors (VEGFR1/2), basic fibroblast growth factor (bFGF), and platelet-derived growth factor (PDGF) A/B was increased in GK rats at both 6 and 7 months. Retinal mRNA expressions of matrix metalloproteinase (MMP) 2/9 and insulin-like growth factor 1 (IGF-1) were increased at 7 months. Retinal mRNA expression of pigment epithelium-derived factor (PEDF) was increased in GK rats at 6 months. Serum contents of VEGF, bFGF, PDGFA, MMP2/9, IGF-1, PEDF were increased in GK rats at both 6 and 7 months, while PDGFB was increased at 7 months. In summary, our results indicate that retinal angiogenesis occurred in GK rats at 6 and 7 months, and the expressions of some angiogenesis related factors were increased during the development of DR in GK rats.