Microvasculature in the Streptozotocin Induced Diabetic Rat Retina

Shin, Ji Man; Chun, Myung Hoon; Oh, Su Ja

Abstract

Diabetic retinopathy is characterized by the pericyte loss, microaneurysms and neovascularization eventually leads to blindness. The present study was examined changes of the microvasculature histochemically and immunochemically in the diabetic rat retina previously documented neuronal alterations, in order to verify the usefulness of the animal model of diabetes for the pathophysiology of angiogenesis. Diabetic condition was induced by a single intravenous injection of streptozotocin in Sprague-Dawley rats aged of 8weeks. The animals showing high blood glucose levels (above 300 mg/dL) were cared for 1, 4, 8, and 12 weeks, respectively. The retinas were processed for Griffonia simplicifolia isolection (GSI) B4 histochmistry, and anti-alpha-smooth muscle actin (alpha-SMA) and anti-NG2 immunochemical techniques. The retinal vasculature was well demarcated by endothelial profiles with GSIB4 histochemistry. alpha-SMA immunoreactivity appeared in the arterioles and the primary capillaries, and NG2 in the arterioles and the whole capillary beds. Changes evoked by diabetes were largely occurred in the capillary. Compared to the retina at normal state, the capillary networks were more complicated, enlarged, and dense. NG2 reactivity was reduced especially under the cytoplasmic processes of the pericytes. In the near periphery of the capillary mainly in the ganglion cell layer of the diabetes, GSIB4 reactive microglia were distributed. These results suggest that the retinal microvasculature showed the precedent events of neovascularization due to diabetes and rat model of diabetes is useful for study of neovascularization mechanism of the diabetic retinopathy.