Melatonin and taurine have alleviative effects in streptozotocin (STZ)-induced
diabetic rats. Male Wistar rats were divided into non-diabetic, diabetic, diabetic
melatonin (administered at 200 μg/kg/day dissolved in 0.5 ml of normal saline) and
diabetic taurine (administered at 2% in the drinking water) supplemented groups. At
the end of the study, blood was collected and used for determination of glucose, total
cholesterol, triglyceride levels, liver enzymes (ALT and AST), β-hydroxybutyrate (β-
HB), in addition to advanced oxidation protein product (AOPP) level, and
paraoxonase (PON1) enzyme activity. Also, liver tissue was examined for
malondialdhyde (MDA) level, glutathione peroxidase (GPx) enzyme activity and
cytochrome P450 2E1 (CYP2E1) both enzyme activity and gene expression. Light
microscopy pictures of liver tissue were also evaluated for signs of its damage. An
increased CYP2E1 activity and gene expression with a concomitant significant
change in oxidative stress parameters were found in STZ-induced diabetic rats,
suggesting the possible diabetes-induced injury. Taurine or melatonin
supplementation to the diabetic rats alleviated these experimental parameters with
more significant effect for taurine than that of melatonin. Suppression of β-HB
production by taurine can be one of the mechanisms of reduction in CYP2E1.
Conclusion: Taurine has the capabilities more than melatonin in protecting the liver
from the hepatic injury induced by type 1 diabetes, by reducing the oxidative stress
and restoring CYP2E1 activity and gene expression, suggesting hepatic protective
nature of taurine in diabetic rats. Therefore antioxidants might prove beneficial as an
adjuvant treatment to insulin in type 1 diabetes associated with manifestations of liver
injury.