Abstract
Purpose::
Recently, we reported that angiotensin converting enzyme (ACE) activity and vascular endothelial growth factor (VEGF) concentration were significantly higher in the vitreous of proliferative diabetic retinopathy (PDR) patients than macular hole patients and that ACE levels were significantly correlated with VEGF levels in that of PDR patients (Am J Ophthalmol. 2006 ;141:129-134). Spontaneously Diabetic Torii (SDT) rat is a new model of non-obese type 2 diabetes, and it is thought to be useful for the study of diabetic retinopathy. In this study, we compared retinal mRNA levels of NADPH oxidase subunit p22phox and VEGF between SDT rats and normal rats, and we further evaluated these levels in angiotensin II-infused SDT rats.
Methods::
We measured retinal mRNA levels of p22phox and VEGF in 30-week-old male SDT rats and Sprague-Dawley(SD) rats as normal rats. To evaluate the effect of angiotensin II, ten-week-old male SDT rats were subjected to an 8-week infusion of angiotensin II (50 ng/kg per min) via subcutaneous osmotic minipumps and we measured retinal mRNA levels of p22phox and VEGF at 30 weeks old.
Results::
mRNA levels of p22phox and VEGF were higher 3.56 fold and 1.71 fold in SDT rats than SD rats, respectively. Moreover, the p22phox and VEGF were higher 1.44 fold and 1.89 fold in angiotensin II-infused SDT rats than in non-infused SDT rats, respectively.
Conclusions::
In a new model of non-obese type 2 diabetes SDT rats, retinal p22phox and VEGF gene expressions were increased. The p22phox and VEGF gene expressions were further increased after angiotensin II infusion. These observations suggest that angiotensin II may be involved in retinal gene expression of NADPH oxidase-mediated VEGF in diabetic retinopathy.
Keywords: diabetic retinopathy • growth factors/growth factor receptors • oxidation/oxidative or free radical damage