Protective Effect of Insulin Treatment on Early Renal Changes in Streptozotocin-Induced Diabetic Rats

Objectives: Chronic kidney disease is a progressive complication of diabetes mellitus (DM). This study aimed to analyse early renal changes in streptozotocin induced diabetic rats and demonstrate the effect of early treatment with insulin on kidney's histology. Methods: 30 male-adult Sprague-Dawley rats were included in the study. Diabetes was induced in 24 of the rats by a single injection of 65 mg/kg streptozotocin dissolved in saline. 5 units/day NPH insulin injection was started to 10 rats as treatment group and 11 rats were followed untreated. 6 rats constituted the control group. Induction of diabetes failed in 3 animals and 3 untreated rats died during the study. After 21 days, all rats were sacrificed and their kidneys were removed to obtain histological sections to be evaluated by light microscopy. Results: Ten treated and 8 untreated diabetic rats and 6 healthy controls, totally 24 rats completed the study. There was a significant weight loss in treated and untreated diabetic groups and a weight gain in the control group (p<0.05). Final blood glucose levels were significantly higher in untreated diabetic group when compared to treated diabetic and control groups and higher in treated diabetic group when compared to control group. Histological analysis of kidney sections showed normal morphology in control group. Changes like increased mesangium, tubular atrophy and tubules with dilated lumen and irregular cell shapes were found in the untreated group whereas, glomerulus and mesangium showed similar morphology with control group with a few changes in tubules, in insulin-treated group. Conclusion: In DM, renal changes start at an early point and it is possible to prevent/delay those changes at this point with early intervention of insulin treatment.