Renoprotective effects of oryzanol in an animal model of experimentally induced diabetic nephropathy

摘要

Hyperglycemia-mediated oxidative stress is an important causal factor for the development and progression of diabetic nephropathy. Hence, the present study was hypothesized to explore the renoprotective potential of oryzanol, a commercially-important antioxidant component isolated from crude rice bran oil, in diabetes-induced experimental nephropathy. Wistar rats were administered streptozotocin (45 mg/kg i.v., once) to induce experimental diabetes mellitus. Animals were then divided into the following groups; normal control rats, diabetic rats, diabetic rats administered with oryzanol (50 and 100 mg/kg) and diabetic rats administered with standard glibenclamide (10 mg/kg) orally. Following 8 weeks of streptozotocin injection and respective treatments, fasting blood glucose, biochemical markers of renal function and renal oxidative stress were evaluated in serum, urine and kidney tissue, together with histopathological assessment. The results revealed that treatment with oryzanol significantly improved the glycemic status and renal function in diabetic rats with respect to marked normalization on the levels of creatinine, uric acid, blood urea nitrogen, albumin, urinary albumin:creatinine ratio, kidney tissue enzyme, total protein, serum lipid profile and electrolyte concentrations in a dose-dependent manner. Further, oryzanol supplementation revealed a considerable dose-dependent improvement in superoxide dismutase and catalase activities and reduced glutathione levels, with a significant decline in the extent of lipid peroxidation in diabetic kidneys. Histopathological observations also evidenced regression in renal pathological alterations with oryzanol. Therefore, oryzanol confers marked protection against functional and morphologic injuries in the kidneys of diabetic rats by modulating renal alterations, improving serum lipid profile and attenuating the markers of oxidative and/or nitrosative stress in renal tissues.