α-Terpineol Induces Gastric Retention of Liquids by Inhibiting Vagal Parasympathetic Pathways in Rats

Abstract

-Terpineol is a monoterpene with smooth muscle relaxant properties. In this study, its effects on the gastric emptying rate of awake rats were evaluated with emphasis on the mode by which it induces gastrointestinal actions. Administered by gavage, -terpineol (50 mg/kg) delayed gastric emptying of a liquid test meal at 10 min postprandial. Hexamethonium or guanethidine did not interfere with the retarding effect induced by-terpineol, but atropine and L-N-nitroarginine methyl ester abolished it. In vagotomized rats, -terpineol did not delay gastric emptying. In isolated strips of gastric fundus, concentration-effect curves in response to carbamylcholine were higher in magnitude after treatment with the monoterpene.-Terpineol (1 to 2000 µM) relaxed sustained contractions induced by carbamylcholine or a high K concentration in a concentration-dependent manner. This relaxing effect was not affected by the presence of L-N-nitroarginine methyl ester, 1 H-[1, 2, 4]oxadiazolo[4,3-a]quinoxalin-1-one, tetraethylammonium, or atropine. Smooth muscle contractions induced by electrical field stimulation were inhibited by -terpineol. In conclusion,-terpineol induced gastric retention in awake rats through mechanisms that depended on intact vagal innervation to the stomach, which involved cholinergic/nitrergic signalling. Such a retarding effect induced by -terpineol appears not to result from a direct action of the monoterpene on gastric smooth muscle cells.

Gas Chromatography-Triple Quadrupole Mass Spectrometry Analysis and Vasorelaxant Effect of Essential Oil fromProtium heptaphyllum(Aubl.) March.

“…Besides the activities described above, monoterpenes also produce significant effects on the cardiovascular system, promoting, among other actions, vasorelaxation, decreased heart rate, and hypotension [ 30 ]. Constituents of the essential oil of P. heptaphyllum exhibit biological activities, as p -cymene presents anti-inflammatory property [ 31 ], D-limonene presents antihyperalgesic action [ 32 ], and α -terpineol induces gastric protection [ 33 ].…”

The effects of medicinal plants on muscarinic receptors in various types of smooth muscle

“…This relaxing effect was not affected by atropine. Therefore, α‐terpineol induced relaxant effect on gastric strips in rats via mechanisms other than cholinergic/nitrergic signaling (da Silva et al, ).…”