Selenium in diabetes: Effects of selenium on nephropathy in type I streptozotocin-induced diabetic rats

Abstract

Oxidative stress is involved in diabetes mellitus and its complications. Selenium is a nutritional antioxidant, especially because it is required for the activity of selenium-dependent glutathione peroxidase. Selenium also may have insulin-like properties and improve insulin sensitivity. However, its effects are not sufficiently documented in diabetes and its complications. Thus we supplemented type I diabetic rats with a selenium-rich yeast, selenomethionine and selenomethionine + vitamin E for 24 weeks. Selenium supplementations increased selenium levels in plasma. Selenium and more efficiently Sm + vitamin E decreased plasma glucose level and glycated hemoglobin. Supplementations increased selenium levels in kidney and double supplementation increased renal vitamin E level. However, no differences were observed in thiobarbituric acid-reactive substances in kidneys in the different groups. Selenium decreased or normalized the increased arachidonic acid content observed in diabetic kidneys and so may reduce the level of thromboxane involved in nephropathy. Glomerular hyperfiltration is common in early stages of diabetic nephropathy. We observed an increased renal creatinine clearance in diabetic rats, indicating renal hyperfiltration. Nevertheless, this hyperfiltration was corrected by selenium supplementations. Renal lesions were markedly increased in diabetic rats, but very significantly reduced or corrected by supplementations. Thus we concluded that selenium supplementation could be a useful additive therapeutic to delay diabetic nephropathy. J. Trace Elem. Exp. Med. 12:379–392, 1999. © 1999 Wiley-Liss, Inc.