TRPV1 receptor signaling mediates afferent nerve sensitization during colitis-induced motility disorders in rats

Abstract

BY. TRPV1 receptor signaling mediates afferent nerve sensitization during colitis-induced motility disorders in rats. Am J Physiol Gastrointest Liver Physiol 294: G245-G253, 2008. First published November 8, 2007 doi:10.1152/ajpgi.00351.2007.-Rats with experimental colitis suffer from impaired gastric emptying (GE). We previously showed that this phenomenon involves afferent neurons within the pelvic nerve. In this study, we aimed to identify the mediators involved in this afferent hyperactivation. Colitis was induced by trinitrobenzene sulfate (TNBS) instillation. We determined GE, distal front, and geometric center (GC) of intestinal transit 30 min after intragastric administration of a semiliquid Evans blue solution. We evaluated the effects of the transient receptor potential vanilloid type 1 (TRPV1) antagonists capsazepine (5-10 mg/kg) and N- (4-tertiarybutylphenyl)-4-(3-cholorphyridin-2-yl)tetrahydropyrazine-1(2H)carboxamide (BCTC; 1-10 mg/kg) and the calcitonin generelated peptide (CGRP) receptor antagonist CGRP-(8-37) (150 g/ kg). To determine TRPV1 receptor antagonist sensitivity, we examined their effect on capsaicin-induced relaxations of isolated gastric fundus muscle strips. Immunocytochemical staining of TRPV1 and RT-PCR analysis of TRPV1 mRNA were performed in dorsal root ganglion (DRG) L6 -S1. TNBS-induced colitis reduced GE but had no effect on intestinal motility. Capsazepine reduced GE in controls but had no effect in rats with colitis. At doses that had no effects in controls, BCTC and CGRP-(8-37) significantly improved colitis-induced gastroparesis. Capsazepine inhibited capsaicininduced relaxations by 35% whereas BCTC completely abolished them. TNBS-induced colitis increased TRPV1-like immunoreactivity and TRPV1 mRNA content in pelvic afferent neuronal cell bodies in DRG L6 -S1. In conclusion, distal colitis in rats impairs GE via sensitized pelvic afferent neurons. We provided pharmacological, immunocytochemical, and molecular biological evidence that this sensitization is mediated by TRPV1 receptors and involves CGRP release. gastric emptying; sensory nerve; pelvic nerve; CGRP PATIENTS WITH INFLAMMATORY bowel disease (IBD) often suffer from disorders of gastrointestinal motility and sensitivity, imposing a significant load on the patient's quality of life (20). These alterations are known to appear both during inflammatory episodes and in periods of remission and can occur either at the site of inflammation or at a distance from this site (43). Especially concerning the latter situation, little is known about the underlying pathophysiological mechanisms. There have been several studies documenting the effects of isolated experimental colitis on small intestinal neuromuscular function, but the in vivo consequences on gut transit were inconclusive (3, 5, 29). McHugh et al. (37) reported that rats with trinitrobenzene sulfate (TNBS)-induced colitis suffer from a reduction of gastric emptying but did not investigate the underlying mechanisms. We recently confirmed that rats with experimental...

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“…The data presented here confirm previous studies showing that both TRPV1 and TRPA1 mRNA in DRG are increased following CFA injection into the skin (Ji et al, 2002; Amaya et al, 2004; Obata et al, 2005; Malin et al, 2006; Diogenes et al, 2007; Xu et al, 2007) or TNBS inflammation in the colon (De Schepper et al, 2008b; De Schepper et al, 2008a; Yang et al, 2008), but with differing time courses depending on the site of inflammation. Expression of NGF and GDNF family members is coincidentally increased in inflamed tissues and also with a distinct pattern of expression for cutaneous versus visceral structures.…”

Citrobacter rodentium colitis evokes post‐infectious hyperexcitability of mouse nociceptive colonic dorsal root ganglion neurons

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The G Protein–Coupled Receptor–Transient Receptor Potential Channel Axis: Molecular Insights for Targeting Disorders of Sensation and Inflammation

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