NDT Advance Access published online on April 20, 2007
Nephrology Dialysis Transplantation, doi:10.1093/ndt/gfm166
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Pyridoxal phosphate prevents progression of diabetic nephropathy
1Department of Clinical Preventive Medicine, Nagoya University Hospital, Nagoya, Japan, 2Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China and 3Institute of Pharmacy and Food Chemistry, University of Erlangen-Nürnberg, Erlangen, Germany
Correspondence and offprint requests to: Toshimitsu Niwa, Department of Clinical Preventive Medicine, Nagoya University Hospital, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8560, Japan. Email: tniwa{at}med.nagoya-u.ac.jp
| Abstract |
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Background. We have demonstrated that pyridoxal 5'-phosphate (PLP), an active form of vitamin B6, inhibits formation of advanced glycation end-products (AGEs) by trapping 3-deoxyglucosone. The present study aimed to clarify if PLP could exert beneficial effects on nephropathy in diabetic rats.
Methods. Streptozotocin (STZ)-induced diabetic rats were treated by oral administration of PLP or pyridoxamine (PM), another active form of vitamin B6, at a dose of 600 mg/kg/day for 16 weeks. AGEs [imidazolone, N
-(carboxymethyl)lysine (CML) and N2-carboxyethyl-2'-deoxyguanosine (CEdG)], transforming growth factor-ß1 (TGF-ß1), type 1 collagen and fibronectin were detected in the kidneys using immunohistochemistry. Gene expression of TGF-ß1 and receptor for AGEs (RAGEs) in the kidneys was determined using real-time quantitative polymerase chain reaction.
Results. Administration of PLP significantly inhibited albuminuria, glomerular hypertrophy, mesangial expansion, and interstitial fibrosis as compared with diabetic rats. PLP markedly inhibited accumulation of AGEs such as imidazolone, CML and CEdG, a DNA-linked AGE, in glomeruli. PLP significantly inhibited expression of TGF-ß1, type 1 collagen, fibronectin and RAGE in the kidneys. PLP was superior to PM in inhibiting accumulation of AGEs, expression of TGF-ß1, type 1 collagen, and fibronectin, and the development of diabetic nephropathy.
Conclusions. PLP prevented progression of nephropathy in STZ-induced diabetic rats by inhibiting formation of AGEs. PLP is considered a promising active form of vitamin B6 for the treatment of AGE-linked disorders such as diabetic nephropathy.
Keywords: advanced glycation end-products (AGEs); diabetic nephropathy; pyridoxal 5'-phosphate (PLP); receptor for advanced glycation end-products (RAGE); transforming growth factor-ß1 (TGF-ß1)
Received for publication: 3. 6.06
Accepted in revised form: 5. 3.07