title: Cytokine regulation of gut ornithine decarboxylase gene expression and enzyme activity.
abstract: BACKGROUND
  The enzyme ornithine decarboxylase (ODC) catalyzes the rate-limiting step in polyamine biosynthesis and is important for gut mucosal repair after systemic injury (e.g., burns); however, the mechanisms responsible for the injury-mediated induction of ODC are not known. The purpose of this study was to determine whether interleukin-1 (IL-1) or tumor necrosis factor (TNF), which are released immediately after injury, regulates gut mucosal ODC enzyme activity and gene expression.
  
  
  METHODS
  In vivo: In experiment 1, 64 male BALB/c mice received either recombinant IL-1 beta (2 x 10(4) units/kg administered intraperitoneally) or saline solution. In experiment 2, 64 mice received either recombinant TNF-alpha (100 micrograms/kg administered intraperitoneally) or saline solution. We determined ODC enzyme activity and ODC mRNA levels in small intestine and kidneys at 2, 4, 12, and 24 hours after injection. In vitro: We also determined the ODC enzyme activity in intestinal epithelial crypt cells after either IL-1 beta or TNF-alpha treatment.
  
  
  RESULTS
  IL-1, but not TNF, increased small intestinal ODC enzyme activity. In addition, IL-1 increased ODC enzyme activity in intestinal epithelial crypt cells at 5 and 6 hours after treatment. Both IL-1 and TNF increased small intestinal ODC mRNA levels. Neither agent affected ODC enzyme activity or ODC mRNA levels in the kidney.
  
  
  CONCLUSIONS
  These results suggest that the cytokine-mediated induction of ODC in the small intestine is tissue specific, that the induction occurs at multiple cellular levels, and that ODC may play a vital role in the restoration of gut mucosa that occurs after injury.
authors.affiliation: Department of Surgery, University of Texas Medical Branch, Galveston 77550.
authors.forename: D H
authors.initials: DH
authors.lastname: Chung
authors.forename: B M
authors.initials: BM
authors.lastname: Evers
authors.forename: C M
authors.initials: CM
authors.lastname: Townsend
authors.forename: D N
authors.initials: DN
authors.lastname: Herndon
authors.forename: T C
authors.initials: TC
authors.lastname: Ko
authors.forename: T
authors.initials: T
authors.lastname: Uchida
authors.forename: J C
authors.initials: JC
authors.lastname: Thompson
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D015870:Gene Expression; D007375:Interleukin-1 / Q000494:pharmacology*; D007422:Intestines / Q000201:enzymology*; D009955:Ornithine Decarboxylase / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D007375:Interleukin-1; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D009955:Ornithine Decarboxylase