Effect of oral vanadyl sulphate on ultrastructure of pancreatic islets beta cells in streptozotocin-induced diabetic rats

Considering insulin like effects of vanadium salts, these compounds have been evaluted as a therapeutic agent for treatment of diabetes mellitus in the experimental models of the disease in animals. This study was performed to study the ultrastructure of islet β cells in streptozotocin (STZ)- induced diabetes in rats after treatment with vanadyl sulfate (VS). Diabetes was induced in male Wistar rats by intravenous injection of 40 mg/kg STZ. Equal volume of normal saline was injected via lateral tail vein in sham animals. Seven days after injection animals in both groups were divided into treated and control groups.VS was added to the drinking water of the diabetic treated (DT) and Sham treated (NT) animals with a concentration of 0.5 mg/ml for one week and 1 mg/ml up to three months. Untreated diabetic (DC) and sham rats (NC) received tap water during this period. Two months later all animals were killed. Langerhans islets were isolated from exocrine parts by use of collagen digestion, and were fixed in glutaraldehyde. Ultrastructure of islet beta cells were studied by means of transmission electron microscope. VS treatment led to amelioration of the symptoms of diabetes including hyperglycemia and polydepsia in DT rats. DC rats remained diabetic during the period of study. No significant changes were observed in plasma glucose and fluid intake of NT animals. Ultrastructural studies of islet β cells of DT rats showed normal cells with normal chromatin distribution, well-developed rough endoplasmic reticulum, increased cytoplasmic granules and no clear sign of cell injury. Lymphocytic infiltration was not detected in langerhans islets of DT group. Nuclear pyknosis, cytoplasmic vacuolization, lymphocytic infiltration and signs of cell death such as cell necrosis were found in the islets of β cells of DC rats. Cytoplasm of islets β cells of NT rats were more granular in comparison to NC rats. Considering the results of this study we concluded that amelioration of diabetes signs in VS treated STZ induced diabetic rats are accompanied by preservation of islets β cell ultrastructure.