Abstract
Diabetic nephropathy (DN) is one of the most important renal complications associated with diabetes, and the mechanisms are yet to be fully understood. To date, few studies have shown the antioxidant effects of 1α,25-dihydroxyvitamin-D3 [1,25(OH)2D3] on hyperglycemia-induced renal injury. The aim of the present study was to explore the potential mechanism by which 1,25(OH)2D3 reduced oxidative stress in diabetic rat kidneys. In this study, we established a vitamin D-deficient spontaneous diabetes model: 5-6 wk of age Zucker diabetic fatty (ZDF) rats were treated with or without 1,25(OH)2D3 for 7 wk, age-matched Zucker lean rats served as control. Results showed that ZDF rats treated with 1,25(OH)2D3 had decreased body mass, food intake, water intake, and urine volume. 1,25(OH)2D3 ameliorated urine glucose, blood glucose and abnormal glucose tolerance. Additionally, 1,25(OH)2D3 significantly lowered microalbuminuria, decreased the glomerular basement membrane thickness, and in some degree inhibited glomerular hypertrophy, mesangial expansion, and tubular dilatation. Furthermore, 1,25(OH)2D3 attenuated renal oxidative damage, as reflected by the levels of malondialdehyde, reduced glutathione, 4-hydroxynonenal, 8-hydroxy-2'-deoxyguanosine, and reactive oxygen species production, and notably inhibited poly(ADP-ribose) polymerase-1 (PARP1), activated sirtuin 1 (SIRT1), and decreased the expression of NADPH oxidase 4 (NOX4). Of interest, the abovementioned proteins could be involved in the antioxidant mechanism of 1,25(OH)2D3 in diabetic rat kidneys. Our study showed that oxidative stress might be a major contributor to DN pathogenesis and uncovered the antioxidant role of 1,25(OH)2D3 in diabetic nephropathy that was associated with the PARP1/SIRT1/ NOX4 pathway.