title: Expression of cyclooxygenase genes in the jejunum of horses during low-flow ischemia and reperfusion.
abstract: OBJECTIVE
  To determine expression of cyclooxygenase (COX) genes 1 and 2 (also called prostaglandin-endoperoxide synthases 1 and 2) and stability of housekeeping gene expression during low-flow ischemia and reperfusion in the jejunum of horses.
  
  
  METHODS
  5 healthy adult horses.
  
  
  METHODS
  Horses were anesthetized, and two 30-cm segments of jejunum were surgically exteriorized. Blood flow was maintained at baseline (untreated) values in 1 (control) segment and was decreased to 20% of baseline (low-flow ischemia) for 75 minutes, followed by 75 minutes of reperfusion, in the other (experimental) segment. Biopsy samples were collected from experimental segments at baseline (T0), after 75 minutes of ischemia (T1), and after 75 minutes of reperfusion (T2); samples were collected from control segments at T0 and T2. Horses were euthanized 24 hours after induction of ischemia (T3), and additional samples were collected. Samples were evaluated histologically. Total RNA was extracted; expression of COX genes and stability of 8 housekeeping genes were determined via quantitative real-time PCR assays.
  
  
  RESULTS
  COX-1 and COX-2 genes were constitutively expressed in baseline samples. Low-flow ischemia resulted in significant upregulation of COX-2 gene expression at each subsequent time point, compared with baseline values. The most stably expressed reference genes were β-actin and hypoxanthine phosphoribosyltransferase, whereas glyceraldehyde 3-phosphate dehydrogenase and β-2 microglobulin were the least stably expressed.
  
  
  CONCLUSIONS
  Low-flow ischemia resulted in upregulation of COX-2 gene expression in the jejunum of horses. Housekeeping genes traditionally used as internal standards may not be stable in this tissue during arterial low-flow ischemia and reperfusion.
authors.affiliation: Department of Surgical and Radiological Sciences, Comparative Gastrointestinal Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. hhilton@stanford.edu
authors.forename: Hugo
authors.initials: H
authors.lastname: Hilton
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Nieto
authors.forename: Peter F
authors.initials: PF
authors.lastname: Moore
authors.forename: Faye A
authors.initials: FA
authors.lastname: Harmon
authors.forename: Diane K
authors.initials: DK
authors.lastname: Naydan
authors.forename: Jack R
authors.initials: JR
authors.lastname: Snyder
mesh_terms: D000818:Animals; D051545:Cyclooxygenase 1 / Q000235:genetics*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006734:Horse Diseases / Q000378:metabolism / Q000473:pathology*; D006736:Horses; D007511:Ischemia / Q000378:metabolism / Q000662:veterinary*; D007579:Jejunal Diseases / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D007583:Jejunum / Q000098:blood supply* / Q000378:metabolism / Q000473:pathology; D008297:Male; D015427:Reperfusion Injury / Q000378:metabolism / Q000662:veterinary*; D015854:Up-Regulation
chemical_list: D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2