Abstract

BACKGROUND: Sirtuin (Sirt) 3 could promote autophagy by downregulating the expression of genes related to neovascularization in retinal endothelial cells. In this study, we aimed to investigate the effect of Sirt3 overexpression on retinopathy in streptozotocin (STZ)-induced diabetic rats, and to assess its mechanisms.

MATERIAL AND METHODS: Ntraperitoneal injection of STZ in rats was used to produce a diabetic model. The study rats were divided into 4 groups (n=6 for each group): a control group; a model group; a model+scrambled adenovirus group; and a model+Sirt3 overexpression group. Hematoxylin and eosin (H&E) staining determined the pathological changes of retina tissues. Immunohistochemistry, fluorescence quantitative polymerase chain reaction, and western blotting were used to detect the expression of Sirt3, vascular endothelial growth factor (VEGF), and microtubule-associated protein 1A/1B-light chain 3 (LC3).

RESULTS: In the model group, the inner limiting membrane was swollen, uneven and thickened, and the capillary endothelial cells occasionally protruded into the inner limiting membrane. These abnormalities were prevented by Sirt3 overexpression. Compared with the control group, the expression of Sirt3 at both mRNA and protein levels in the model group was significantly reduced, while the expression of VEGF was increased versus the control group (P<0.05). The expression of LC3 at both mRNA and protein levels was not different between the model group and the control group. Compared with the model group, the expression of Sirt3, LC3, and LC3-II was significantly increased, while the expression of VEGF was significantly decreased in the model+Sirt3 overexpression group (P<0.05).

CONCLUSIONS: Sirt3 overexpression has a preventive effect on diabetic retinopathy likely through promoting the expression of autophagy-related proteins and downregulating the expression of VEGF.

Keywords: Autophagy, Diabetes Mellitus, Type 2, Diabetic Retinopathy, Diabetes Mellitus, Experimental, endothelial cells, Retina, Sirtuins, Vascular Endothelial Growth Factor A