title: P2X3 receptors mediate visceral hypersensitivity during acute chemically-induced colitis and in the post-inflammatory phase via different mechanisms of sensitization.
abstract: OBJECTIVE
  Experiments using P2X3 knock-out mice or more general P2X receptor antagonists suggest that P2X3 receptors contribute to visceral hypersensitivity. We aimed to investigate the effect of the selective P2X3 antagonist A-317491 on visceral sensitivity under physiological conditions, during acute colitis and in the post-inflammatory phase of colitis.
  
  
  METHODS
  Trinitrobenzene sulphonic-acid colitis was monitored by colonoscopy: on day 3 to confirm the presence of colitis and then every 4 days, starting from day 10, to monitor convalescence and determine the exact timepoint of endoscopic healing in each rat. Visceral sensitivity was assessed by quantifying visceromotor responses to colorectal distension in controls, rats with acute colitis and post-colitis rats. A-317491 was administered 30 min prior to visceral sensitivity testing. Expression of P2X3 receptors (RT-PCR and immunohistochemistry) and the intracellular signalling molecules cdk5, csk and CASK (RT-PCR) were quantified in colonic tissue and dorsal root ganglia. ATP release in response to colorectal distension was measured by luminiscence.
  
  
  RESULTS
  Rats with acute TNBS-colitis displayed significant visceral hypersensitivity that was dose-dependently, but not fully, reversed by A-317491. Hypersenstivity was accompanied by an increased colonic release of ATP. Post-colitis rats also displayed visceral hypersensitivity that was dose-dependently reduced and fully normalized by A-317491 without increased release of ATP. A-317491 did not modify visceral sensitivity in controls. P2X3 mRNA and protein expression in the colon and dorsal root ganglia were similar in control, acute colitis and post-colitis groups, while colonic mRNA expression of cdk5, csk and CASK was increased in the post-colitis group only.
  
  
  CONCLUSIONS
  These findings indicate that P2X3 receptors are not involved in sensory signaling under physiological conditions whereas they modulate visceral hypersensitivity during acute TNBS-colitis and even more so in the post-inflammatory phase, albeit via different mechanisms of sensitization, validating P2X3 receptors as potential new targets in the treatment of abdominal pain syndromes.
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.
authors.forename: Annemie
authors.initials: A
authors.lastname: Deiteren
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.
authors.forename: Laura
authors.initials: L
authors.lastname: van der Linden
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.
authors.forename: Anouk
authors.initials: A
authors.lastname: de Wit
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.
authors.forename: Hannah
authors.initials: H
authors.lastname: Ceuleers
authors.affiliation: Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
authors.forename: Roeland
authors.initials: R
authors.lastname: Buckinx
authors.affiliation: Laboratory of Cell Biology and Histology, University of Antwerp, Antwerp, Belgium.
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Timmermans
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium; Antwerp University Hospital, Department of Gastroenterology and Hepatology, Antwerp, Belgium.
authors.forename: Tom G
authors.initials: TG
authors.lastname: Moreels
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium; Antwerp University Hospital, Department of Gastroenterology and Hepatology, Antwerp, Belgium.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Pelckmans
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.
authors.forename: Joris G
authors.initials: JG
authors.lastname: De Man
authors.affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.
authors.forename: Benedicte Y
authors.initials: BY
authors.lastname: De Winter
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003092:Colitis / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D003106:Colon / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006930:Hyperalgesia / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D010636:Phenols / Q000494:pharmacology; D011083:Polycyclic Compounds / Q000494:pharmacology; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D058477:Receptors, Purinergic P2X3 / Q000378:metabolism*; D014302:Trinitrobenzenesulfonic Acid
chemical_list: C470346:A-317491; D010636:Phenols; D011083:Polycyclic Compounds; D058920:Purinergic P2X Receptor Antagonists; D058477:Receptors, Purinergic P2X3; D000255:Adenosine Triphosphate; D014302:Trinitrobenzenesulfonic Acid