Anti-diabetic effect of a monoamine oxidase inhibitor (tranylcypromine) in rats with poorly-controlled blood glucose levels: A potential and novel therapeutic option for diabetes

Purpose: To determine the anti-diabetic effect of a monoamine oxidase inhibitor (tranylcypromine) in sulphonyl urea-refractory rats with poorly-controlled blood glucose levels. Methods: Alloxan-induced diabetic Wistar rats were assigned to two groups (30 rats/group). One group received glibenclamide at a dose of 0.6 mg/kg, while the other group was given monoamine oxidase inhibitor (tranylcypromine) at a dose of 5 mg/day. The two groups were treated for 2 weeks. Blood samples were collected at baseline (before treatment) and at the end of treatment for determination of plasma glucose (fasting and fed), hemoglobin A1c, lipid profiles (serum total cholesterol, very-low-density lipoprotein, low-density lipoprotein, high-density lipoprotein and triglycerides); oxidative stress parameters (anti-oxidant enzymes), insulin levels, and some hepatic enzymes of glucose metabolism. Results: Monoamine oxidase inhibitor treatment resulted in significant decrease in the levels of blood glucose, HbA1c, and lipid levels from baseline, relative to glibenclamide (p < 0.05). Greater improvements in oxidative stress biomarkers (glutathione and superoxide dismutase), insulin levels and hepatic enzymes of glucose metabolism were observed in monoamine oxidase inhibitor group than in glibenclamide group (p < 0.05). Oxidative stress was significantly inhibited by monoamine oxidase inhibitor via increases in glutathione (GSH) level and superoxide dismutase (SOD) activity, when compared to glibenclamide (p < 0.05). Conclusion: These results suggest that monoamine oxidase inhibitor may be a better treatment option for diabetes than glibenclamide.