Amato Antonella, Serio Rosa, Mulè Flavia
Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128 Palermo, Italy.
Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128 Palermo, Italy.
Eur J Pharmacol. 2014 Dec 15;745:129-34. doi: 10.1016/j.ejphar.2014.10.012. Epub 2014 Oct 16.
We have previously demonstrated that menthol reduces murine gastric tone in part through a neural mechanism, involving adrenergic pathways and reduction of ongoing release of acetylcholine from enteric nerves. In the present study we aimed to verify whether the gastric relaxation to menthol may be triggered by interaction with neural receptors or ionic channels proteins, such as transient receptor potential (TRP)-melastatin8 (TRPM8), TRP-ankyrin 1 (TRPA1), 5-hydroxytriptamine 3 (5-HT3) receptor or cholinergic nicotinic receptors. Spontaneous mechanical activity was detected in vitro as changes in intraluminal pressure from isolated mouse stomach. Menthol (0.3-30 mM) induced gastric relaxation which was not affected by 5-benzyloxytryptamine, a TRPM8 receptor antagonist, HC030031, a TRPA1 channel blocker. In addition, allylisothiocyanate, a TRPA1 agonist, but not (2S,5R)-2-Isopropyl-N-(4-methoxyphenyl)-5-methylcyclohexanecarboximide, a selective TRPM8 agonist, induced gastric relaxation. Genic expression of TRPA1, but not of TRPM8, was revealed in mouse stomach. Indeed, menthol-induced gastric relaxation was significantly reduced by hexamethonium, cholinergic nicotinic receptor antagonist. Menthol, at concentrations that failed to affect gastric tone, reduced the contraction induced by dimethylphenylpiperazinium, nicotinic receptor agonist. The joint application of hexamethonium and atropine, muscarinc receptor antagonist, or hexamethonium and phentholamine, α-adrenergic receptor antagonist, did not produce any additive reduction of the relaxant response to menthol. Lastly, ondansetron, a 5-HT3 receptor antagonist, was ineffective. In conclusion, our study suggests that nicotinic receptors, but not TRP and 5-HT3 receptors, are molecular targets for menthol inducing murine gastric relaxation, ultimately due to the reduction of acetylcholine release from enteric nerves.
我们之前已经证明，薄荷醇部分通过神经机制降低小鼠胃张力，这涉及肾上腺素能途径以及减少肠神经中乙酰胆碱的持续释放。在本研究中，我们旨在验证薄荷醇引起的胃舒张是否可能由与神经受体或离子通道蛋白的相互作用触发，如瞬时受体电位（TRP）-褪黑素8（TRPM8）、TRP-锚蛋白1（TRPA1）、5-羟色胺3（5-HT3）受体或胆碱能烟碱受体。体外通过测量分离的小鼠胃腔内压力变化来检测自发机械活动。薄荷醇（0.3 - 30 mM）诱导胃舒张，该舒张不受TRPM8受体拮抗剂5-苄氧基色胺、TRPA1通道阻滞剂HC030031的影响。此外，TRPA1激动剂异硫氰酸烯丙酯可诱导胃舒张，但选择性TRPM8激动剂（2S,5R）-2-异丙基-N-（4-甲氧基苯基）-5-甲基环己烷甲酰胺则不能。在小鼠胃中检测到TRPA1的基因表达，但未检测到TRPM8的基因表达。实际上，胆碱能烟碱受体拮抗剂六甲铵可显著降低薄荷醇诱导的胃舒张。薄荷醇在未能影响胃张力的浓度下，可降低烟碱受体激动剂二甲基苯基哌嗪诱导的收缩。六甲铵与毒蕈碱受体拮抗剂阿托品或六甲铵与α-肾上腺素能受体拮抗剂酚妥拉明联合应用，并未对薄荷醇的舒张反应产生任何相加性降低作用。最后，5-HT3受体拮抗剂昂丹司琼无效。总之，我们的研究表明，烟碱受体而非TRP和5-HT3受体是薄荷醇诱导小鼠胃舒张的分子靶点，最终是由于肠神经中乙酰胆碱释放减少所致。
