Introduction: The use of experimental models is essential to study the pathophysiological mechanisms of diabetes.
Objectives: To compare in adult Wistar rats the diabetogenic action of streptozotocin according to the moment and route of administration during the neonatal period by evaluating biochemical, metabolic and histological variables.
Materials and methods: Eight groups of neonatal female Wistar rats (n=10) were formed. We evaluated the induction with streptozotocin (100 mg/kg of body weight) on days 2 and 5 after birth, as well as the administration routes (subcutaneous or intraperitoneal). Controls were injected with sodium citrate buffer. Blood glucose level, body weight, food and water intake were monitored for 12 weeks. We also performed tolerance tests for oral glucose and glycosylated hemoglobin, and a histopathological pancreas morphometric study.
Results: The mortality rate was about 100% among rats given streptozotocin on their fifth day of life. All rats receiving the drug on day 2 of life survived, and they showed a marked hyperglycemia, polyphagia, polydipsia and decreased body weight gain in addition to increased glycosylated hemoglobin rates and impaired results in the oral glucose tolerance test. Histopathological lesions of the pancreas as well as a decreased number of islets were significantly more frequent in rats receiving the drug subcutaneously on day 2, which confirms that streptozotocin administered subcutaneously produces greater damage.
Conclusions: Subcutaneous injection of streptozotocin in a dose of 100 mg/kg of body weight in the second day after birth induced moderate diabetes in adult Wistar rats more effectively.
Keywords: Diabetes mellitus; experimental; glucose; hyperglycemia; islets of Langerhans; rats; streptozotocin.