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Binit Kumar, S. Gupta, B. Srinivasan, Tapas Nag, Sushma Srivastava, Rohit Saxena; Quercetin protects retinal vascular degeneration through anti-angiogenic mechanisms in STZ-induced diabetic rats. Invest. Ophthalmol. Vis. Sci. 2013;54(15):5561.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the protective effects of Quercetin (Qctn, Oral Dose-25mg/kg Body Weight), a plant based flavonol, on hyperglycemia induced retinal vasculopathy in diabetic rats.
The study was carried out for a period of 24 weeks in STZ-induced diabetic rats. The study groups (normal, diabetic & Qctn-treated diabetic rats) were evaluated for retinal angiogenic parameters (VEGF and PKC-β) by ELISA and retinal vascular leakage by fluorescein angiography. Retinal vessel diameters [retinal arteriolar (AD) and venular (VD) diameter] were estimated in fundus images. Retinal vessel abnormalities were observed through periodic monitoring of rat fundus. Further, transmission electron microscopy (TEM) was done to determine capillary basement membrane (BM) thickness and Endothelium/Pericyte (E/P) ratio.
A significant rise in the expression of VEGF and PKC-β in diabetic retinae (25.12±4.26 & 131.19±12.42 pg/mg protein, respectively) was recorded as compared to normal retinae (7.30±1.08 & 34.19±5.26 pg/mg protein, respectively). On the other hand, Qctn-treated retinae showed significant inhibition of VEGF and PKC-β expression (15.24±2.01 & 73.50±11.57 pg/mg protein, respectively). Fundus Fluorescein angiograms from diabetic retinae showed increased retinal vascular permeability and leakage, but was absent in Qctn-treated retinae. Moreover, there was significant increase in vessel caliber in diabetic retinae (AD, 62.99±1.74 µm & VD, 97.38±2.20 µm) compared to normal retinae (AD, 47.83±1.87 µm & VD, 74.14±1.92 µm). On the contrary, Qctn-treated retinae showed lesser dilated retinal vessels (AD, 55.23±2.60 µm & VD,82.94±1.81 µm). TEM showed degenerated capillary pericytes and endothelium, and swollen Muller cell processes. However, Qctn-treated retinae showed normal endothelium and pericyte structures. Further, TEM study showed thickened BM (0.19±0.02 µm) and increased E/P ratio in diabetic retinae as compared to normal retinae. On the contrary, Qctn-treated retinae showed comparatively thin BM (0.14±0.01 µm) and decreased E/P ratio.
Based on the results, it can be concluded that Qctn may be effective for the prevention/treatment of diabetes induced retinal microvascular complications.
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