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M Jarrin, H Sánchez, P Fernández, A García-Layana, M López; Streptozotocin Induced Diabetes in Wistar Rat: Is it a Good Model of Diabetic Retinopathy? . Invest. Ophthalmol. Vis. Sci. 2002;43(13):1334.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Pathological mechanisms of diabetic retinopathy (DR),the leading cause of blindness in developed countries are still unknown. Therefore animal models are necessary to improve knowledge on physiological and pathological changes in order to propose potential treatments. Thus, the purpose of this work is: To evaluate the usefulness of the streptozotocin (STZ) diabetes rat model as an experimental model of non proliferative DR. Methods: Wistar rats weighting between 200 and 250 g were used. Two groups were establish: control group (CG) (n= 10) and a diabetic group (DG)(n=20). Diabetes was induced by using estreptozotocin (75 mg /Kg) and maintained 10 months. Diabetic animals were treated with insulin. Weight and glycemic control were tested every day and values of Hb A1c every 4 months. After euthanasia eyes were enucleated. Retina was analysed by optical microscopy (OM) and vascular endothelial growth factor (VEGF) by western blot. Results: All rats of CG survived but only 50% of DG. Mean weight of CG at the end of the experiment was 481,5g (41,2), mean blood glucose 93,1 mg/dl (5,15) and Hb A1c 3,1% (0,28). Only 80 % of the rats that had received STZ and survived became diabetic. Mean weigh at the end of experiment was 441,4 g (67,7), glucose 219,16 mg/dl (149,71) and Hb A1c 6,5% (3,46). Nearly 30% of DG developed cataracts around the 4th month. Retinal analysis by OM did not show differences between CG and DG. Values of VEGF were 30,69 units in RPE and 17, 69 in outer retina in CG. In DG values were 53.1 and 35,56 respectively. Diabetes induced by STZ is easily reproducible however it has an elevated mortality and although ultrastructural changes have been demonstrated, there were no differences in the optical study after 10 months. Only initial changes and biochemical modifications can be studied. VEGF has been implicated in severe conditions of DR. Animal model used in this work allows its measurements in severe diabetic conditions. Conclusions: This animal model is not useful for advanced RD. Nevertheless could be useful in the study of the biochemical changes involved in retinal barriers rupture and for cataract development.
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