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P2X3 receptors mediate visceral hypersensitivity during acute chemically-induced colitis and in the post-inflammatory phase via different mechanisms of sensitization.

Deiteren A, van der Linden L, de Wit A, Ceuleers H, Buckinx R, Timmermans JP, Moreels TG, Pelckmans PA, De Man JG, De Winter BY - PLoS ONE (2015)

Bottom Line: Hypersenstivity was accompanied by an increased colonic release of ATP.A-317491 did not modify visceral sensitivity in controls.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.

ABSTRACT

Objectives: 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.

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Effect of A-317491 in acute TNBS-colitis compared to the post-inflammatory phase of colitis.To substantiate a difference in potency of A-317491 to reduce visceral hypersensitivity during acute TNBS-colitis compared to the post-inflammatory phase of colitis, data are expressed as the percentage of improvement of normalization: 0% means no improvement and thus the same level of hypersensitivity as vehicle-treated rats during acute TNBS-colitis or in the post-inflammatory phase, whereas 100% means complete normalization of the increased VMRs (reaching the level of vehicle-treated controls). Both the 10 mg/kg (A) and the 25 mg/kg (B) dose of A-317491 more potently reduced visceral hypersensitivity in the post-inflammatory phase of colitis compared to the acute inflammatory phase of colitis. Generalized estimating equations, LSD post-hoc test, n = 7–8; * p<0.05, significantly different compared to acute colitis.
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pone.0123810.g004: Effect of A-317491 in acute TNBS-colitis compared to the post-inflammatory phase of colitis.To substantiate a difference in potency of A-317491 to reduce visceral hypersensitivity during acute TNBS-colitis compared to the post-inflammatory phase of colitis, data are expressed as the percentage of improvement of normalization: 0% means no improvement and thus the same level of hypersensitivity as vehicle-treated rats during acute TNBS-colitis or in the post-inflammatory phase, whereas 100% means complete normalization of the increased VMRs (reaching the level of vehicle-treated controls). Both the 10 mg/kg (A) and the 25 mg/kg (B) dose of A-317491 more potently reduced visceral hypersensitivity in the post-inflammatory phase of colitis compared to the acute inflammatory phase of colitis. Generalized estimating equations, LSD post-hoc test, n = 7–8; * p<0.05, significantly different compared to acute colitis.

Mentions: During acute colitis, A-317491 dose-dependently, but not fully reversed visceral hypersensitivity, even at the highest dose of 25 mg/kg (Fig 2). However, in post-colitis rats the 10 mg/kg dose already normalized VMRs (Fig 3). To substantiate a difference in potency of A-317491 in reducing visceral hypersensitivity between the acute phase of colitis and the post-inflammatory phase, the effect of A-317491 on VMRs was expressed as the percentage of improvement or normalization (Fig 4): 0% indicates no improvement (compared to vehicle-treated acute colitis or post-colitis rats) whereas 100% accounts for full normalization of the VMRs (to the level of vehicle-treated controls). In post-colitis rats both the 10 and the 25 mg/kg dose of A-317491 were more effective in reducing the increased VMRs compared to the effect of A-317491 in rats in the acute phase of colitis (Fig 4).


P2X3 receptors mediate visceral hypersensitivity during acute chemically-induced colitis and in the post-inflammatory phase via different mechanisms of sensitization.

Deiteren A, van der Linden L, de Wit A, Ceuleers H, Buckinx R, Timmermans JP, Moreels TG, Pelckmans PA, De Man JG, De Winter BY - PLoS ONE (2015)

Effect of A-317491 in acute TNBS-colitis compared to the post-inflammatory phase of colitis.To substantiate a difference in potency of A-317491 to reduce visceral hypersensitivity during acute TNBS-colitis compared to the post-inflammatory phase of colitis, data are expressed as the percentage of improvement of normalization: 0% means no improvement and thus the same level of hypersensitivity as vehicle-treated rats during acute TNBS-colitis or in the post-inflammatory phase, whereas 100% means complete normalization of the increased VMRs (reaching the level of vehicle-treated controls). Both the 10 mg/kg (A) and the 25 mg/kg (B) dose of A-317491 more potently reduced visceral hypersensitivity in the post-inflammatory phase of colitis compared to the acute inflammatory phase of colitis. Generalized estimating equations, LSD post-hoc test, n = 7–8; * p<0.05, significantly different compared to acute colitis.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401691&req=5

pone.0123810.g004: Effect of A-317491 in acute TNBS-colitis compared to the post-inflammatory phase of colitis.To substantiate a difference in potency of A-317491 to reduce visceral hypersensitivity during acute TNBS-colitis compared to the post-inflammatory phase of colitis, data are expressed as the percentage of improvement of normalization: 0% means no improvement and thus the same level of hypersensitivity as vehicle-treated rats during acute TNBS-colitis or in the post-inflammatory phase, whereas 100% means complete normalization of the increased VMRs (reaching the level of vehicle-treated controls). Both the 10 mg/kg (A) and the 25 mg/kg (B) dose of A-317491 more potently reduced visceral hypersensitivity in the post-inflammatory phase of colitis compared to the acute inflammatory phase of colitis. Generalized estimating equations, LSD post-hoc test, n = 7–8; * p<0.05, significantly different compared to acute colitis.
Mentions: During acute colitis, A-317491 dose-dependently, but not fully reversed visceral hypersensitivity, even at the highest dose of 25 mg/kg (Fig 2). However, in post-colitis rats the 10 mg/kg dose already normalized VMRs (Fig 3). To substantiate a difference in potency of A-317491 in reducing visceral hypersensitivity between the acute phase of colitis and the post-inflammatory phase, the effect of A-317491 on VMRs was expressed as the percentage of improvement or normalization (Fig 4): 0% indicates no improvement (compared to vehicle-treated acute colitis or post-colitis rats) whereas 100% accounts for full normalization of the VMRs (to the level of vehicle-treated controls). In post-colitis rats both the 10 and the 25 mg/kg dose of A-317491 were more effective in reducing the increased VMRs compared to the effect of A-317491 in rats in the acute phase of colitis (Fig 4).

Bottom Line: Hypersenstivity was accompanied by an increased colonic release of ATP.A-317491 did not modify visceral sensitivity in controls.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.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology, University of Antwerp, Antwerp, Belgium.

ABSTRACT

Objectives: 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.

Show MeSH
Related in: MedlinePlus