The impact of 1,25-dihydroxy vitamin D3 on the expressions of vascular endothelial growth factor and transforming growth factor-β1 in the retinas of rats with diabetes

Aims: To define whether 1,25-dihydroxy vitamin D3 (1,25-(OH)(2) D-3) can protect diabetic retinopathy and to investigate its impact on the expressions of vascular endothelial growth factor (VEGF) and transforming growth factor-beta(1) (TGF-beta(1)) in the retinas of rats with diabetes. Methods: Male Sprague-Dawley (SD) rats were divided into normal control group, 1,25-(OH)(2) D-3 group and diabetes group. The rats in 1,25-(OH)(2) D-3 group and diabetes group were established to type 2 diabetes model with high-fat and high-sugar diet and streptozotocin (STZ). Meanwhile, the rats of 1,25-(OH)(2) D-3 group were treated with 1,25-(OH)(2) D-3. After 13 weeks, morphological changes of retinal tissues were observed under microscopes after hematoxylin-eosin staining. VEGF and TGF-beta(1) expressions in the retinal tissues were detected with immunohistochemistry staining. Results: Pathological examination showed an appearance of edema and disordered arrangement of retinal tissues in diabetes group, but milder pathological changes in 1,25-(OH)(2) D-3 group. VEGF and TGF-beta(1) expressions of both diabetes group and 1,25-(OH)(2) D-3 group significantly increased (P < 0.05), but those of 1,25-(OH)(2) D-3 group were significantly lower than diabetes group (P < 0.05). Conclusion: 1,25-(OH)(2) D-3 had partially protective effect on diabetic retinopathy of diabetic rats, the mechanism of which might inhibit VEGF and TGF-beta(1) expressions in the retinal tissues. (C) 2012 Elsevier Ireland Ltd. All rights reserved.