title: Involvement of cholinergic nicotinic receptors in the menthol-induced gastric relaxation.
abstract: 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.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128 Palermo, Italy. Electronic address: antonella.amato@unipa.it.
authors.forename: Antonella
authors.initials: A
authors.lastname: Amato
authors.affiliation: Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128 Palermo, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Serio
authors.affiliation: Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche (STEBICEF), Università di Palermo, 90128 Palermo, Italy.
authors.forename: Flavia
authors.initials: F
authors.lastname: Mulè
mesh_terms: D000083:Acetanilides / Q000494:pharmacology; D000818:Animals; D005769:Gastrointestinal Motility / Q000187:drug effects / Q000502:physiology; D017879:Isothiocyanates / Q000494:pharmacology; D008297:Male; D008610:Menthol / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D017294:Ondansetron / Q000494:pharmacology; D011687:Purines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011978:Receptors, Nicotinic / Q000502:physiology*; D012701:Serotonin / Q000031:analogs & derivatives / Q000494:pharmacology; D058831:Serotonin 5-HT3 Receptor Antagonists / Q000494:pharmacology; D013270:Stomach / Q000187:drug effects* / Q000502:physiology*; D000074025:TRPA1 Cation Channel; D050053:TRPM Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics; D050051:Transient Receptor Potential Channels / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics
chemical_list: C552888:2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide; D000083:Acetanilides; D017879:Isothiocyanates; D011687:Purines; D012333:RNA, Messenger; D011978:Receptors, Nicotinic; D058831:Serotonin 5-HT3 Receptor Antagonists; D000074025:TRPA1 Cation Channel; D050053:TRPM Cation Channels; C492297:TRPM8 protein, mouse; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse; D008610:Menthol; C070179:5-benzyloxytryptamine; D012701:Serotonin; D017294:Ondansetron; C004471:allyl isothiocyanate
keywords: Gastric relaxation; Menthol; Menthol (PubChem CID: 16666); Nicotinic receptors; TRPA1; TRPM8