The protective effect of NG-nitro-L-arginine methyl ester and insulin on nitric oxide inhibition and pathology in experimental diabetic rat liver

Objectives: To determine on protective role of NG-nitro-L-arginine methyl ester (L-NAME), and insulin on the liver in streptozotocin (STZ) induced diabetic rats. Methods: This study was performed in the Department of Biochemistry, Faculty of Medicine, Eskisehir Osmangazi University, Eskisehir, Turkey in 2007. Forty male Wistar albino rats were divided into 5 groups. These were untreated, diabetic control, STZ+insulin, STZ+L-NAME and STZ+insulin+L-NAME induced groups. The STZ was intraperitonally injected into 3 groups, and includes insulin, L-NAME, and their joint administrations as protective agents. The blood glucose and nitric oxide (NO) levels were determined. The tissue samples were obtained at the end of the fourth week. The liver tissue distortions were evaluated using hematoxylin and eosin staining. Results: The serum glucose level was significantly higher in diabetic control (p=0.000), than the untreated group. Nitric oxide level was significantly lower in STZ+L-NAME (p=0.000) than the untreated group. The focal pseudo lobular structures without vena centralis increased portal fibrillary necrosis, and bile duct stenosis with coagulation necrosis of the peripheral hepatocytes were more observed in diabetic group than the protective agent groups. In addition, insulin, and L-NAME lead to hepatocyte regeneration; and minimal mononuclear cell infiltration was noted. Conclusion: NG-nitro-L-arginine methyl ester inhibits NO level in STZ+L-NAME induced group. NG-nitro-L-arginine methyl ester either alone, or with insulin combination significantly attenuates the liver morphological disarrangements in STZ induced diabetic rats.