Antioxidant Status and Anti-inflammatory Effects of Oleuropein in Streptozotocin-induced Diabetic Nephropathy in Rats

The aim of the study was the evaluation of the potentially antioxidant and anti-inflammatory effects of oleuropein against streptozotocin (STZ)-induced diabetic nephropathy in rats. Animals were allocated into 4 groups of 8 rats each. The control group was fed standard rat feed and received no added treatment. In the oleuropein group, oleuropein was given to normal animals at a dosages of 20 mg/kg intraperitoneally (i.p) for 28 days. In the diabetic group, STZ was injected into rats at a single dose of 50 mg/kg i.p. The last group, oleuropein was given to diabetic animals at dosage of 20 mg/kg i.p for 28 days. STZ induced significant increases of inflammation cytokines as serum TNF-α, IL-6, IL-10, IL-18, and IF-γ. Also, serum blood urea nitrosamine and creatinine levels as markers of nephropathy were increased in the diabetic group. STZ increased kidney total oxidant status, malondialdehyde, superoxide dismutase and catalase whereas it decreased total antioxidant capacity. In addition, kidneys were examined by histopathological and immunohistochemical methods; mononuclear cell infiltration, proliferations, tubular dilatations, vacuolar degenerations, and red-brown cytoplasmic and nuclear expansion were observed in STZ-induced diabetic rats. In contrast, oleuropein decreased amelioration of oxidant status and tissue damage in diabetic rats. In conclusion, oleuropein treatment shows an antioxidant and anti-inflammatory effects in diabetes by decreasing oxidative stress and regenerated kidney tissue.