Attenuation of Glomerular Injury in Diabetic Mice with Tert-Butylhydroquinone through Nuclear Factor Erythroid 2-Related Factor 2-Dependent Antioxidant Gene Activation

Background/Aims: Nuclear factor erythroid 2-related factor 2 (Nrf2) is a positive regulator of the expression of antioxidant genes. This study is aimed at examining the effect of tert-butylhydroquinone (tBHQ), an activator of Nrf2, on hyperglycemia-related diabetic nephropathy. Methods: CD-1 mice were induced with streptozotocin and treated with 1% tBHQ, or omitting it, in their diet for 12 weeks. Four and twelve weeks later, the levels of serum and glomerular malondialdehyde (MDA), blood glucose, kidney and body weights, and proteinuria were measured. The pathogenic process in the kidney was examined histologically and by transmission electron microscopy. The relative levels of Nrf2, heme oxygenase-1 (HO-1), gamma-glutamylcysteine synthethase (gamma-GCS) expression and nuclear accumulation of Nrf2 in the glomeruli were determined by reverse transcription polymerase chain reaction and Western blot assays. Results: In the glomeruli of diabetic mice, treatment with tBHQ significantly reduced the levels of serum and glomerular MDA, kidney weight and proteinuria, decreased fibronectin accumulation and mitigated the pathogenic processes. It also enhanced Nrf2, HO-1 and gamma-GCS expression and Nrf2 nuclear accumulation. Conclusions: tBHQ has beneficial effects on reducing hyperglycemia-induced kidney injury, which is associated with the enhanced expression of Nrf2, and its downstream antioxidant HO-1 and gamma-GCS in the glomeruli of diabetic mice. Copyright (C) 2011 S. Karger AG, Basel