De Schepper H U, De Man J G, Ruyssers N E, Deiteren A, Van Nassauw L, Timmermans J-P, Martinet W, Herman A G, Pelckmans P A, De Winter B Y
Laboratory of Gastroenterology, Faculty of Medicine, Univ. of Antwerp, Universiteitsplein 1, 2610 Antwerp (Belgium
Am J Physiol Gastrointest Liver Physiol. 2008 Jan;294(1):G245-53. doi: 10.1152/ajpgi.00351.2007. Epub 2007 Nov 8.
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 gene-related peptide (CGRP) receptor antagonist CGRP-(8-37) (150 microg/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 capsaicin-induced 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.
患有实验性结肠炎的大鼠存在胃排空（GE）受损的情况。我们之前表明，这种现象涉及盆神经内的传入神经元。在本研究中，我们旨在确定参与这种传入神经高激活的介质。通过三硝基苯磺酸（TNBS）灌肠诱导结肠炎。在胃内给予半液体伊文思蓝溶液30分钟后，我们测定了GE、肠道转运的远端前沿和几何中心（GC）。我们评估了瞬时受体电位香草酸受体1（TRPV1）拮抗剂辣椒素（5 - 10毫克/千克）和N -（4 - 叔丁基苯基）- 4 -（3 - 氯吡啶 - 2 - 基）四氢吡嗪 - 1（2H）甲酰胺（BCTC；1 - 10毫克/千克）以及降钙素基因相关肽（CGRP）受体拮抗剂CGRP -（8 - 37）（150微克/千克）的作用。为了确定TRPV1受体拮抗剂的敏感性，我们检查了它们对辣椒素诱导的离体胃底肌条舒张的影响。在腰6 - 骶1背根神经节（DRG）中进行了TRPV1的免疫细胞化学染色和TRPV1 mRNA的逆转录聚合酶链反应（RT - PCR）分析。TNBS诱导的结肠炎降低了GE，但对肠道运动没有影响。辣椒素在对照组中降低了GE，但在患有结肠炎的大鼠中没有作用。在对对照组无影响的剂量下，BCTC和CGRP -（8 - 37）显著改善了结肠炎诱导的胃轻瘫。辣椒素抑制辣椒素诱导的舒张作用达35%，而BCTC则完全消除了这种作用。TNBS诱导的结肠炎增加了DRG腰6 - 骶1中盆传入神经元细胞体中TRPV1样免疫反应性和TRPV1 mRNA含量。总之，大鼠远端结肠炎通过致敏的盆传入神经元损害GE。我们提供了药理学、免疫细胞化学和分子生物学证据，表明这种致敏是由TRPV1受体介导的，并且涉及CGRP释放。
