Comparative Study of the Protective Effects of Taurine and Melatonin on Cytochrome P450 2E1 and some Oxidative Stress Markers in Streptozotocin-induced Diabetic Rats

Melatonin and taurine have alleviative effects in streptozotocin (STZ)-induceddiabetic rats. Male Wistar rats were divided into non-diabetic, diabetic, diabeticmelatonin (administered at 200 μg/kg/day dissolved in 0.5 ml of normal saline) anddiabetic taurine (administered at 2% in the drinking water) supplemented groups. Atthe end of the study, blood was collected and used for determination of glucose, totalcholesterol, triglyceride levels, liver enzymes (ALT and AST), β-hydroxybutyrate (β-HB), in addition to advanced oxidation protein product (AOPP) level, andparaoxonase (PON1) enzyme activity. Also, liver tissue was examined formalondialdhyde (MDA) level, glutathione peroxidase (GPx) enzyme activity andcytochrome P450 2E1 (CYP2E1) both enzyme activity and gene expression. Lightmicroscopy pictures of liver tissue were also evaluated for signs of its damage. Anincreased CYP2E1 activity and gene expression with a concomitant significantchange in oxidative stress parameters were found in STZ-induced diabetic rats,suggesting the possible diabetes-induced injury. Taurine or melatoninsupplementation to the diabetic rats alleviated these experimental parameters withmore significant effect for taurine than that of melatonin. Suppression of β-HBproduction by taurine can be one of the mechanisms of reduction in CYP2E1.Conclusion: Taurine has the capabilities more than melatonin in protecting the liverfrom the hepatic injury induced by type 1 diabetes, by reducing the oxidative stressand restoring CYP2E1 activity and gene expression, suggesting hepatic protectivenature of taurine in diabetic rats. Therefore antioxidants might prove beneficial as anadjuvant treatment to insulin in type 1 diabetes associated with manifestations of liverinjury.