Supplemental dietary arginine reduces renal RAGE expression and oxidative damage in rats with streptozotocin-induced type 2 diabetes

Background & aims: Arginine (Arg) was shown to have immunomodulatory effect and inhibits advanced glycation end product (AGE) formation in in vitro studies. This study investigated the effects of dietary Arg supplementation on renal receptor of AGE (RAGE) expressions and oxidative damage in diabetic rats. Methods: There were 1 normal control (NC) group and 2 diabetic groups in this study. Rats in the NC group were fed with a chow diet. One diabetic group (DM) was fed a common semipurified diet, while the other diabetic group received a diet in which part of the casein was replaced by Arg (DM-Arg) for 8 wk. Diabetes was induced by an intraperitoneal injection of nicotinamide followed by streptozotocin. Rats with blood glucose levels exceeding 180 mg/dL were considered diabetic. Blood samples were collected at the baseline and 8 wk. Kidneys of the animals were harvested at the end of the study for further analysis. Results: Plasma fructosamine contents were significantly higher in the diabetic groups than in the NC group. The DM group had higher fructosamine than the DM-Arg group. Kidney nitrotyrosine concentrations and nuclear factor-κB p65 protein expressions were significantly lower in the DM-Arg group than in the DM group. The result of immunohistochemical staining also showed that the expressions of RAGE in the kidneys were significantly lower in the DM-Arg group than in the DM group. Conclusions: These results suggest that dietary Arg supplementation may decrease renal RAGE expressions and oxidative damage in rats with type 2 diabetes.