Evidence based analysis of chemical method of induction of diabetes mellitus in experimental rats

Abstract

There have been several reports expressing doubt concerning the use of chemical induction of diabetes mellitus in experimental animals as a suitable model for studying type II diabetes mellitus. This study is designed to assess whether there is a significant difference in response by chemically (alloxan) induced hyperglycaemic (AIH) and oral glucose loading induced hyperglycaemic (GIH) wistar rats to antidiabetic agents. AIH was achieved through intraperitoneal administration of alloxan monohydrate (150mg/kg body weight) to rats, while GIH was induced in another group of rats by administering orally (2.5g/kg body weight) of glucose solution. The two sets of rats represent hyperglycaemia with insufficient pancreatic activity and hyperglycaemia with intact pancreas functions respectively. Two standard antidiabetic agents namely: metformin (20mg/kg) and tolbutamide (20mg/kg body weight) and two plant extracts namely: Vernonia amygdalina and Mangifera indica (200mg/kg body weight) leaves extracts were used as the antidiabetic agents. The results showed that, administration of 150mg/kg of alloxan monohydrate successfully raised the blood glucose levels in 75% of the treated rat’s to ≥ 150mg/dl after 72 hours, while oral loading of the rats with 2.5g/kg body weight of glucose solution produced hyperglycemia in 70% of the rats. The maximum blood glucose levels reached after induction with glucose and alloxan were 338.3±61.2mg/dl and 514.7±34.7mg/dl respectively. The highest percentage reductions in blood glucose level achieved after the treatment with the agents were 54.3% in GIH and 67.1% in AIH. The Spearman rank correlation (Rs) calculated for the two sets of data was 0.8261 which is very significant. This finding showed that, chemical induction of diabetes mellitus has no differential effect on the response of antidiabetic agents and the method is suitable for studying type II diabetes mellitus in experimental animals.