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Journal of Biomedicine and Biotechnology
Volume 2010 (2010), Article ID 513853, 7 pages
http://dx.doi.org/10.1155/2010/513853
Research Article

Decrease of Klotho in the Kidney of Streptozotocin-Induced Diabetic Rats

1Division of Nephrology, Department of Internal Medicine, National Cheng Kung University Hospital, Tainan City 70101, Taiwan
2Graduate Institute of Clinical Medicine, College of Medicine, National Cheng Kung University Hospital, Tainan City 70101, Taiwan
3Graduate Institute of Basic Medical Science, College of Medicine, National Cheng Kung University Hospital, Tainan City 70101, Taiwan
4Department of Pharmacology, College of Medicine, National Cheng Kung University Hospital, Tainan City 70101, Taiwan
5Department of Medical Research, Chi-Mei Medical Center, Yong Kang City 73101, Taiwan

Received 24 February 2010; Accepted 22 April 2010

Academic Editor: Nathan Ames Ellis

Copyright © 2010 Meng-Fu Cheng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The klotho gene is expressed in a limited number of tissues, most notably in distal convoluted tubules in the kidney and choroid plexus in the brain. A previous study suggested that Klotho increases resistance to oxidative stress. However, changes of Klotho expression in high glucose-induced oxidative stress remain unclear. In the present study, we used streptozotocin-induced diabetic rats (STZ rats) to examine the effects of insulin, phloridzin or antioxidant, tiron on diabetic nephropathy. Both insulin and phloridzin reversed the lower Klotho expression levels in kidneys of STZ rats by the correction of hyperglycemia. Also, renal functions were improved by these treatments. In addition to the improvement of renal functions, the decrease of Klotho expression in kidney of STZ rats was also reversed by tiron without changing blood glucose levels. The reduction of oxidative stress induced by high glucose can be considered for this action of tiron. This view was further confirmed in vitro using high glucose-exposed Madin-Darby canine kidney (MDCK) epithelial cells. Thus, we suggest that decrease of oxidative stress is not only responsible for the improvement of renal function but also for the recovery of Klotho expression in kidney of STZ rats.