Iranian Journal of Toxicology Volume 9, No 28, Spring 2015 1. MSc. of Histology and Embryology, Department of Biology, Urmia University, Urmia, Iran. 2. Department of Biology, Urmia University, Urmia, Iran. 3. Department of Biology, Razi University, Kermanshah, Iran. * Corresponding Author: E-mail: e_ghanbari90@yahoo.com Protective Effect of Royal Jelly against Renal Damage in Streptozotocin Induced Diabetic Rats Elham Ghanbari *1 , Vahid Nejati 2 , Mehri Azadbakht 3 Received: 29.12.2014 Accepted: 20.01.2015 ABSTRACT Background: Royal jelly has been shown to have antioxidant and antidiabetic effects. The objective of this study was to evaluate the protective effect of RJ against kidney damage in streptozotocin induced diabetic rats. Methods: Thirty two male Wistar rats were divided randomly into four groups (n=8 per group). Normal control and diabetic control groups received 1cc/day distilled water, normal RJ-treated and diabetic RJ-treated groups received 100mg RJ/kg body weight daily. Diabetes was induced by intraperitoneal injection of streptozotocin. At the end of the experiment, urine and kidney samples were collected for biochemical and histopathological analysis. Results: The results showed that diabetes could increase levels of urine urea, total protein and albumin significantly, and could decrease the levels of creatinine and uric acid in urine. In the kidney tissue homogenates, catalase activity and antioxidant power were significantly lower, whereas malondialdehyde levels were significantly higher in diabetic group when compared with control group. Diabetic rats showed severe histological changes in kidney tissues. Treatment of diabetic rats with RJ improved significantly all of these parameters. Conclusion: The present study revealed that treatment with RJ resulted in significant improvement in histopathological alterations in kidney tissue and urine parameters of diabetic rats. This could be due to its antioxidant activity and the ability of RJ for scavenging the free radicals released in diabetes. These findings suggest that RJ has protective effects on kidneys affected by diabetes mellitus. Keyword: Diabetes Mellitus, Oxidative Stress, Rats, Renal, Royal Jelly, Streptozocin. IJT 2015; 1258-1263 INTRODUCTION Diabetic nephropathy is one of the major late complications of diabetes mellitus [1]. The first signs of diabetic nephropathy are characterized by increase in renal size, glomerular volume, and renal load followed by accumulation of glomerular extracellular matrix and an abnormal increase in the urinary albumin excretion. End-stage overt diabetic nephropathy is characterized by hypertension, proteinuria, and progressive renal insufficiency [2]. Impairment of renal function is one of the most important features of diabetes. Decreased urinary concentrations of creatinine and uric acid and increased levels of urea have been shown in diabetes [3]. Chronic hyperglycemia results in elevated production of free radicals, especially reactive oxygen species (ROS) and protein glycosylation and glucose autoxidation in all tissues [4]. Damage of enzymes and cellular organelles and increase in malondialdehyde levels can be caused by increased levels of free radicals and simultaneous decline of antioxidant defense mechanisms [5-7]. In kidneys of diabetic rats, lower activity of key antioxidant enzymes, such as catalase (CAT), superoxide dismutase (SOD) and glutathione-s-transferase, was observed [8]. Short-term effects of diabetes on kidney histology include cortical hypertrophy accompanied by glomerular mesangial hypertrophy. Increased glomerular basement membrane thickness is an indicator of long-term effects of diabetes [9]. Royal jelly (RJ) is a food item secreted from the hypopharyngeal and mandibular glands of the worker honeybees [10]. On the other hand, RJ has antioxidant activity that can
