The Expression of NADPH-diaphorase in Corneal Neovascularization of streptozotocin Induced Diabetic Rat

ABSTRACT

We evaluated the effect of nitric oxide on the corneal neovascularization in diabetic rats. The NADPH-diaphorase histochemistry was used to investigate the relationship between the nitric oxide synthase activity and the corneal neovascularzation of disbetic rats. Sprague-Dawley rats of 6 weeks of age were use in this study. Streptozotocin(65mm/kg, Sigma, USA) was injected intraperitoneally to induce diabetes. N-heptanol was applied to the right eyes of the diabetic rats to induce neovascularization and the left eyes were remained uninjured. After four weeks, 5 eyes of the non-diabetic rats, 5 eyes of the diabetic rats, and 5 eyes of the neovascularized diavetic rats were enucleated. The enucleated eyes were stained with NADPH-diaphorase histochemistry method and examined under the light microscope. Neovascularized corneas showed intense expression of NADPH-diaphorase at the whole layer of epithelium, the superficial stroma, and the walls of new vessels. Corneas of the nondiabetic rats and uninjured those of diabetic rats showed only mild expression of NADPH-diaphorase, and there were no significant difference of expression between them. According to these results, we think that the increased expression of nitric oxide synthase or nitric oxide may be related to the corneal neovascularization in diabetic rats.