Objective: In this work, we studied liver morphology, markers of hepatic oxidative stress and some liver enzymes in diabetic rats treated with the combined leaf extract (CLE) of Vernonia amygdalina (bitter leaf) and Azadirachta indica (neem).
Methods: Diabetes was induced in fasted male Wistar rats with intraperitoneal injection of streptozotocin (STZ). Oral CLE (500 mg/kg body weight) and metformin (150 mg/kg body weight) were administered to different groups of diabetic rats for eight weeks. Blood glucose and change in body weight were estimated weekly. All animals were sacrificed under anaesthesia after eight weeks. Hepatic sections were stained with periodic acid-Schiff. Liver samples were homogenized and assayed for contents of malondialdehyde (MDA) and glutathione peroxidase (GPx), while the plasma was assayed for contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST).
Results: Metformin and CLE treatment produced normoglycaemia in the diabetic rats in the course of the treatment period. Significant increases in body weight were observed in the treatment groups compared with the diabetic control rats (P<0.05). In the control and treatment groups, light microscopic study showed intact hepatic histology. Plasma ALT and AST were not significantly different from the control values in the CLE-treated rats. In addition, from week four onwards, blood glucose concentrations in the CLE-treated rats were not different from the normal control (P>0.05). Besides, hepatic MDA (P<0.05) significantly decreased in the CLE-treated rats compared with the normal control.
Conclusion: These findings suggest that CLE ameliorates hyperglycemia and hepatic oxidative stress when administered to diabetic rats as a chronic regimen, and there was no morphologic or biochemical evidence of liver damage at the dose tested.

Key words: diabetes mellitus, experimental, Vernonia, Azadirachta, plant extracts, hepatotoxicity, oxidative stress, rats