King's College London, Wolfson Centre for Age-Related Diseases, Institute of Psychology, Psychiatry and Neuroscience, Hodgkin Building, Guy's Campus, London, SE1 1UL, UK.
Northern General Hospital, Herries Road, Sheffield, S5 7AU, UK.
Eur J Pharmacol. 2023 Sep 5;954:175897. doi: 10.1016/j.ejphar.2023.175897. Epub 2023 Jun 30.
Capsaicin and allyl isothiocyanate (AITC) activate transient receptor potential (TRP) vanilloid-1 (TRPV1) and TRP ankyrin-1 (TRPA1), respectively. TRPV1 and TRPA1 expression have been identified in the gastrointestinal (GI) tract. GI mucosal functions remain largely undefined for TRPV1 and TRPA1 with side-dependence and regional differences in signalling unclear. Here we investigated TRPV1- and TRPA1-induced vectorial ion transport as changes in short-circuit current (ΔI), in defined segments of mouse colon mucosa (ascending, transverse and descending) under voltage-clamp conditions in Ussing chambers. Drugs were applied basolaterally (bl) or apically (ap). Capsaicin responses were biphasic, with primary secretory and secondary anti-secretory phases, observed with bl application only, which predominated in descending colon. AITC responses were monophasic and secretory, with ΔI dependent on colonic region (ascending vs. descending) and sidedness (bl vs. ap). Aprepitant (neurokinin-1 (NK1) antagonist, bl) and tetrodotoxin (Na channel blocker, bl) significantly inhibited capsaicin primary responses in descending colon, while GW627368 (EP4 receptor antagonist, bl) and piroxicam (cyclooxygenase inhibitor, bl) inhibited AITC responses in ascending and descending colonic mucosae. Antagonism of the calcitonin gene-related peptide (CGRP) receptor had no effect on mucosal TRPV1 signalling, while tetrodotoxin and antagonists of the 5-hydroxytryptamine-3 and 4 receptors, CGRP receptor, and EP1/2/3 receptors had no effect on mucosal TRPA1 signalling. Our data demonstrates the regional-specificity and side-dependence of colonic TRPV1 and TRPA1 signalling, with involvement of submucosal neurons and mediation by epithelial NK1 receptor activation for TRPV1, and endogenous prostaglandins and EP4 receptor activation for TRPA1 mucosal responses.
辣椒素和丙烯基异硫氰酸酯（AITC）分别激活瞬时受体电位（TRP）香草素-1（TRPV1）和 TRP 锚蛋白-1（TRPA1）。TRPV1 和 TRPA1 在胃肠道（GI）中表达。TRPV1 和 TRPA1 的 GI 黏膜功能仍然很大程度上不明确，其信号转导的侧依赖性和区域性差异尚不清楚。在这里，我们在 Ussing 室电压钳条件下，研究了 TRPV1 和 TRPA1 诱导的向量离子转运，即在小鼠结肠黏膜的特定段（升结肠、横结肠和降结肠）中，通过短路电流（ΔI）的变化来表示。药物应用于基底外侧（bl）或顶端（ap）。辣椒素反应呈双相性，有原发性分泌和继发性抗分泌相，仅在基底外侧应用时观察到，主要在降结肠中占主导地位。AITC 反应呈单相性和分泌性，ΔI 取决于结肠区域（升结肠与降结肠）和侧位性（bl 与 ap）。阿瑞匹坦（神经激肽-1（NK1）拮抗剂，bl）和河豚毒素（Na 通道阻滞剂，bl）显著抑制降结肠中辣椒素的原发性反应，而 GW627368（EP4 受体拮抗剂，bl）和吡罗昔康（环氧合酶抑制剂，bl）抑制升结肠和降结肠黏膜中的 AITC 反应。降钙素基因相关肽（CGRP）受体拮抗剂对黏膜 TRPV1 信号无影响，而河豚毒素和 5-羟色胺-3 和 4 受体、CGRP 受体和 EP1/2/3 受体拮抗剂对黏膜 TRPA1 信号无影响。我们的数据表明，结肠 TRPV1 和 TRPA1 信号具有区域性特异性和侧依赖性，涉及黏膜下神经元，并通过 TRPV1 上皮 NK1 受体激活介导，通过内源性前列腺素和 EP4 受体激活介导 TRPA1 黏膜反应。
