Evaluation and Optimization of Effective-dose of Alloxan for Inducing Type-2 Diabetes Mellitus in Long Evans Rat

Background: The optimal effective and safe dose of alloxan for inducing stable diabetes in rats has been long arguable. Lower doses can result in auto-reversion from diabetogenic state to normal state. On the other hand, higher doses cause toxicity and loss of experimental animals since it completely destroys the insulin-producing pancreatic β cells. Therefore, determination of effective as well as safe dose of alloxan to induce stable diabetes in experimental Long Evan rats is crucial for investigating on diabetes. Objective: To determine effective and safe dose of alloxan for inducing a stable diabetes mellitus in Long Evans Rats to facilitate availability of diabetic rats for studying on diabetes. Methods: Healthy adult Long Evans rats (80-156 g) were divided into eight groups and each group contains six rats. One group treated as a nondiabetic control (C) while the other seven groups (Group-2 to Group-8) were used as experimental diabetic groups. Different doses of alloxan (80, 100, 120, 130, 140, 150 and 160 mg/kg body weight) were injected through intraperitoneal routes in overnight fasting group-2 to group-8 rats respectively. Blood glucose levels were monitored before and after administering alloaxan dose (for 7 consecutive weeks) by using a blood glucose meter and test strips. Results: In the case of non-diabetic rats, the normal blood glucose levels were found between 7.75 to 10.8 mmol/L. On the other hand, a slow gradual increment of blood glucose levels were measured among the rats (group-2, group-3 and group-4) treated with low doses of alloxan (80, 100 and 120 mg/kg BW) until 5 weeks. However, the increased blood glucose levels were reverted back to its normal by the following two weeks. Group-5 and Group-6 rats treated with alloxan doses of 130 mg/kg and 140 mg/kg respectively stably increased blood glucose levels during the experimental periods. While rats in group-7 and group-8 (treated with 150 and 160 mg/kg BW) were expired by the experimental period might be due to severe alloxan toxicity. Group-6 rats treated with 140 mg/kg alloxan were more preferable because the diabetic level is much more stable and significant than group-5. Conclusion: The optimum effective dose of alloxan was found to be 140 mg/kg BW for induction of stable diabetes in Long Evan rats.