TRPA1 in mast cell activation-induced long-lasting mechanical hypersensitivity of vagal afferent C-fibers in guinea pig esophagus

Abstract

Yu S, Gao G, Peterson BZ, Ouyang A. TRPA1 in mast cell activation-induced long-lasting mechanical hypersensitivity of vagal afferent C-fibers in guinea pig esophagus. Am J Physiol Gastrointest Liver Physiol 297: G34 -G42, 2009. First published May 7, 2009 doi:10.1152/ajpgi.00068.2009.-Sensitization of esophageal sensory afferents by inflammatory mediators plays an important role in esophageal nociception. We have shown esophageal mast cell activation induces long-lasting mechanical hypersensitivity in vagal nodose C-fibers. However, the roles of mast cell mediators and downstream ion channels in this process are unclear. Mast cell tryptase via protease-activated receptor 2 (PAR2)-mediated pathways sensitizes sensory nerves and induces hyperalgesia. Transient receptor potential A1 (TRPA1) plays an important role in mechanosensory transduction and nociception. Here we tested the hypothesis that mast cell activation via a PAR2-dependent mechanism sensitizes TRPA1 to induce mechanical hypersensitivity in esophageal vagal C-fibers. The expression profiles of PAR2 and TRPA1 in vagal nodose ganglia were determined by immunostaining, Western blot, and RT-PCR. Extracellular recordings from esophageal nodose neurons were performed in ex vivo guinea pig esophageal-vagal preparations. Action potentials evoked by esophageal distention and chemical perfusion were compared. Both PAR2 and TRPA1 expressions were identified in vagal nodose neurons by immunostaining, Western blot, and RT-PCR. Ninety-one percent of TRPA1-positive neurons were of small and medium diameters, and 80% coexpressed PAR2. Esophageal mast cell activation significantly enhanced the response of nodose C-fibers to esophageal distension (mechanical hypersensitivity). This was mimicked by PAR2-activating peptide, which sustained for 90 min after wash, but not by PAR2 reverse peptide. TRPA1 inhibitor HC-030031 pretreatment significantly inhibited mechanical hypersensitivity induced by either mast cell activation or PAR2 agonist. Collectively, our data provide new evidence that sensitizing TRPA1 via a PAR2-dependent mechanism plays an important role in mast cell activationinduced mechanical hypersensitivity of vagal nodose C-fibers in guinea pig esophagus. visceral afferent; sensitization; nociception; protease-activated receptor 2; transient receptor potential A1 ABNORMAL ESOPHAGEAL SENSATIONS are generated from sensory afferent nerve endings in the wall of the esophagus and transmitted to the central nervous system by both spinal (27, 31) and vagal (7,25,30,38) pathways. Esophageal sensory afferent nerves usually are polymodal with their cell bodies situated in either dorsal root ganglion (DRG) or nodose/jugular ganglia (21). A subtype of these afferent nerves, nociceptive afferent, can innervate noxious mechanical, chemical, and thermal stimuli to induce nociception (31,36,37). Under certain conditions, such as tissue damage or inflammation, these processes could be enhanced by peripheral and/or central sensitization and result in esophageal hyperalgesia (14,...

Role of prostaglandin D2 in mast cell activation-induced sensitization of esophageal vagal afferents

“…Second, PGD 2 did not participate in regulation of smooth muscle contraction (intestinal peristalsis) in guinea pig GI tract (24). Our data also indicate that PGD 2 -induced sensitization of esophageal afferents is not secondary to the effect of the PGD 2 metabolite 15d-PGJ 2 , which may interact with TRPA1 in nodose neurons (26,31).…”

“…Nodose ganglia (n ϭ 4) were dissected and processed for immunofluorescence double staining of PGD 2 DP1 and DP2 receptors with isolectin B4 (IB4), as described previously (31). The primary antibodies included rabbit polyclonal anti-DP 1 receptor antibody (1:200 dilution; Cayman Chemical, Ann Arbor, MI) and rabbit anti-DP 2 receptor polyclonal antibody (1:200 dilution; Novus Biologicals, Littleton, CO).…”

“…Whole cell currents were measured using a patch-clamp amplifier (Axopath 200B, Molecular Devices, Sunnyvale, CA), digitized (DIGIDATA 1322A, Molecular Devices), and recorded with a personal computer using pCLAMP9 software (Molecular Devices). Immunofluorescence staining of DP 1 receptors and their colocalizations with DiI in dissociated nodose neurons was performed as described previously (31).…”

“…(20), which has been shown to induce nociception (6, 18) via direct interaction with TRPA1 on sensory neurons (26). Our previous studies demonstrated that the majority of esophageal nodose C fibers expressed TRPA1 and responded to the TRPA1 agonist AITC (31). Whether 15d-PGJ 2 displays activation/sensitization effects on esophageal nodose C fibers is unknown.…”

The role of TRPA1 in visceral inflammation and pain

“…Notably, PAR-2-mediated sensitization of TRPA1 represent a key mechanism in mast cell-mediated mechanical hyperalgesia in the guinea pig esophagus. 45,51 Furthermore, Cattaruza and colleagues have reported that TRPA1 deletion significantly reduced mechanical colonic hyperalgesia induced by PAR-2 activating peptide. 52 The expression of TRPA1 has also been demonstrated in DRG neurons innervating the pancreas, and is believed to participate in inflammation and pain related to acute pancreatitis in mice.…”