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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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Expression of CGRP and P2X3 in dorsal root ganglia.Immunohistochemical detection of CGRP (left panel) and P2X3 (middle panel) on cryosections of a dorsal root ganglion. The right panel shows the merged picture; the white arrows indicate neuronal co-expression of CGRP and P2X3.
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pone.0123810.g005: Expression of CGRP and P2X3 in dorsal root ganglia.Immunohistochemical detection of CGRP (left panel) and P2X3 (middle panel) on cryosections of a dorsal root ganglion. The right panel shows the merged picture; the white arrows indicate neuronal co-expression of CGRP and P2X3.

Mentions: The relative expression of P2X3 unit mRNA in the colon and DRGs was comparable in control, acute colitis and post-colitis rats (Table 3). Immunohistochemical staining of DRGs also revealed no difference in expression of CGRP and P2X3 between control, acute colitis and post-colitis conditions (Table 4; Fig 5). In addition, co-expression levels were similar between all groups. However, RT-PCR did reveal a difference in the mRNA expression of cdk5, csk and CASK, important molecular determinants of P2X3 receptor-mediated signaling (Table 3). Colonic mRNA expression of all three targets was increased in the post-colitis group, whereas mRNA levels were similar in the colon of acute colitis and control rats. The increased expression in post-colitis rats was specific for the colon and was not seen at the DRG level, although we did find evidence of reduced csk mRNA expression in the DRGs L6-S1 (Table 3).


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)

Expression of CGRP and P2X3 in dorsal root ganglia.Immunohistochemical detection of CGRP (left panel) and P2X3 (middle panel) on cryosections of a dorsal root ganglion. The right panel shows the merged picture; the white arrows indicate neuronal co-expression of CGRP and P2X3.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123810.g005: Expression of CGRP and P2X3 in dorsal root ganglia.Immunohistochemical detection of CGRP (left panel) and P2X3 (middle panel) on cryosections of a dorsal root ganglion. The right panel shows the merged picture; the white arrows indicate neuronal co-expression of CGRP and P2X3.
Mentions: The relative expression of P2X3 unit mRNA in the colon and DRGs was comparable in control, acute colitis and post-colitis rats (Table 3). Immunohistochemical staining of DRGs also revealed no difference in expression of CGRP and P2X3 between control, acute colitis and post-colitis conditions (Table 4; Fig 5). In addition, co-expression levels were similar between all groups. However, RT-PCR did reveal a difference in the mRNA expression of cdk5, csk and CASK, important molecular determinants of P2X3 receptor-mediated signaling (Table 3). Colonic mRNA expression of all three targets was increased in the post-colitis group, whereas mRNA levels were similar in the colon of acute colitis and control rats. The increased expression in post-colitis rats was specific for the colon and was not seen at the DRG level, although we did find evidence of reduced csk mRNA expression in the DRGs L6-S1 (Table 3).

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