Egypt. J. Comp. Path &Clinic Path. Vol. 28 No.1, 2015 ; 18- 31 ISSN 1110-7537 18 Therapeutic Effects of Spirulina Platensis on Streptozotocin-Induced Diabetic Rats Safaa Abbas Abed , M.O. El-Shazely, Kawkab A. Ahmed, Essam M. Abdel-mawla and Adel K. Ibrahim  Ministry of Science and Technology, Iraq. Department of Pathology, Faculty of Veterinary Medicine, Cairo University  Arab Academy for Science , Technology and maritime Transport, Alexandria. Department of clinical Pathology, Faculty of Veterinary Medicine, Cairo University ABSTRACT— This study aimed to evaluate the therapeutic effects of Spirulina Platensis on streptozotocin-induced diabetic Rats. The present experimental study was carried out on 80 Albino rats (weighing about 250-300 g) divided randomly into 4 equal groups, 20 rats each. Group 1; served as control , group 2: spirulina treated rats (200 mg/kg.b.w), group 3; STZ diabetic rats (single intra-peritoneal injection of streptozotocin (STZ, 60 mg/kg) and group 4; diabetic rats treated with spirulina (200 mg/kg.b.w) . Serum samples and tissue specimens were collected from pancreas, liver and kidneys at 15, 30 and 45 days post experiment for biochemical and histopathological examinations respectively. The biochemical results revealed significant increase in lipase, α-amylase , AST , ALT , ALP , urea and creatinine levels in the serum of diabetic rats, whereas, the diabetic rat treated with Spirulina showed decrease in those biochemical parameters. The histopathological alterations observed in the pancreas of diabetic rats were vacuolation of epithelial lining pancreatic acini, necrosis and atrophy of β-cells of islets of Langerhans. Concerning liver of diabetic rats, it showed dilatation and congestion of hepatic sinusoids and activation of kupffer cells with dissociation of hepatic cords and cytoplasmic vacuolation of hepatocytes. The renal parenchyma of diabetic rats showed marked congestion of glomerular tuft and intertubular blood capillaries with necrobiotic changes and necrosis of renal tubular epithelium associated with focal mononuclear cell infiltration. Marked improvement in the histopathological picture was noticed in the pancreas, liver and kidneys of diabetic rats treated with Spirulina platensis. From the observed results we could concluded that Spirulina platensis contains many antioxidant compounds that could stimulate regeneration and reactivation of B- cells to produce more insulin and this improvement was confirmed by the biochemical parameters and histopathological findings in the pancreas, liver and kidneys. Key words: Spirulina platensis, Streptozotocin, diabetes, histopathology, rat ——————————  —————————— INTRODUCTION Streptozotocin (STZ; N-nitro derivative of glucosamine) is a naturally occurring, broad spectrum antibiotic and cytotoxic chemical that is particularly toxic to the pancreatic, insulin producing beta cells in mammals (Hayashi et al., 2006). Streptozotocin functions as a DNA synthesis inhibitor in both bacterial and mammalian cells (Bolzan and Bianchi, 2002). In bacterial cells, a specific interaction with cytosine moieties leads to the degradation of the bacterial DNA (Reusser, 1971). In