title: Regulation of osteopontin expression in a rat model of urolithiasis.
abstract: OBJECTIVE
  To investigate the relationship between the expression and regulation of osteopontin (OPN) and urolithiasis.
  
  
  METHODS
  Normal and stone model rats were treated with 1,25-dihydroxyvitamin D3(D3), vitamin K, testosterone or estradiol for 7 days, and the expression of osteopontin and its mRNA were detected with immunohistochemistry and Northern blot, respectively. Crystals deposited in rat kidneys were observed with a polarization microscope. The concentrations of crystal components in rat urine were determined.
  
  
  RESULTS
  The results showed that vitamin K, testosterone and estradiol up-regulated the expression of OPN mRNA and its protein, thus decreasing the precipitation of calcium oxalate in rat kidneys. D3 increased the concentration of calcium in urine, and accelerated the sedimentation of calcium oxalate in rat kidneys.
  
  
  CONCLUSIONS
  These findings indicate that OPN may be an important macromolecule in the normal endogenous inhibition of the formation of urolithiasis. Vitamin K, testosterone and estradiol inhibit the formation of stones via up-regulating the expression of OPN in kidneys, while D3 over dose may accelerate the process.
authors.affiliation: Institute of Urology, First Affiliated Hospital of Peking University, Beijing 100034, China.
authors.forename: L
authors.initials: L
authors.lastname: Chang
authors.forename: T
authors.initials: T
authors.lastname: Feng
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Dou
authors.forename: J
authors.initials: J
authors.lastname: Wei
authors.forename: Y
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D007668:Kidney / Q000378:metabolism; D008297:Male; D053495:Osteopontin; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012795:Sialoglycoproteins / Q000096:biosynthesis* / Q000502:physiology*; D014545:Urinary Calculi / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; D053495:Osteopontin