Ameliorative Effects of Allium sativum Extract on iNOS Gene Expression and NO Production in Liver of Streptozotocin + Nicotinamide-Induced Diabetic Rats.

Diabetes mellitus (DM) is one of the most prevalent diseases in the world, which is strongly associated with liver dysfunction. Hyperglycemia, through an oxidative stress pathway, damages various tissues. Herbal medicine is a good candidate to ameliorate hyperglycemia and oxidative stress. In this study, the effects of aqueous Allium sativum (garlic) extract (AGE) on gene expression of inducible nitric oxide synthases (iNOS) and production of nitric oxide (NO) were evaluated in the liver tissue of diabetic rats. Four groups of rats contained normal control rats, garlic control rats (AGE), Streptozotocin (STZ) + nicotinamide-induced diabetic rats (DM), and diabetic rats treated with garlic (DM + AGE). Glucose levels and liver enzymes activities were determined by colorimetric assay in the serum. Gene expression of iNOS by real-time PCR, NO levels by Griess method, oxidative stress parameters by spectrophotometric method and histopathological examination by hematoxylin and eosin staining method were evaluated in the liver tissues. Glucose levels, activities of liver enzymes, oxidative stress markers, iNOS gene expression, and NO production increased significantly in diabetic rats in comparison with control rats, whereas after oral administration of garlic, these parameters decreased significantly, close to the normal levels. Hence, the beneficial effects of garlic on the liver injury of diabetes could be included in the hypoglycaemic and antioxidant properties of garlic via a decrease in gene expression of iNOS and subsequent NO production.