Synergistic effect between 5-HT4 receptor agonist and phosphodiesterase 4-inhibitor in releasing acetylcholine in pig gastric circular muscle in vitro

• Published in: European journal of pharmacology Vol. 781; pp. 76 - 82
• Main Authors: Lefebvre, Romain A., Van Colen, Inge, Pauwelyn, Vicky, De Maeyer, Joris H.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-06-2016
• Subjects: 5-HT4 receptor; Acetylcholine - secretion; Acetylcholine release; Aminopyridines - pharmacology; Animals; Azabicyclo Compounds - pharmacology; Benzamides - pharmacology; Benzofurans - pharmacology; Cyclic Nucleotide Phosphodiesterases, Type 4 - metabolism; Cyclopropanes - pharmacology; Dose-Response Relationship, Drug; Drug Synergism; Gastrointestinal Motility - drug effects; Male; Muscle Contraction - drug effects; Muscle, Smooth - drug effects; Muscle, Smooth - physiology; Muscle, Smooth - secretion; Phosphodiesterase 4; Phosphodiesterase 4 Inhibitors - pharmacology; Prucalopride; Receptors, Serotonin, 5-HT4 - metabolism; Serotonin 5-HT4 Receptor Agonists - pharmacology; Stomach; Stomach - drug effects; Stomach - physiology; Sus scrofa; Velusetrag; Phosphodiesterase 4; Velusetrag; Stomach; Acetylcholine release; Prucalopride; 5-HT4 receptor; 5-HT receptor
• ISSN: 0014-2999; 1879-0712
• DOI: 10.1016/j.ejphar.2016.04.003

5-HT4 receptor agonists have a gastroprokinetic effect by facilitating acetylcholine release from cholinergic nerves innervating gastrointestinal smooth muscle. The role of phosphodiesterase (PDE) 4 in the signal transduction pathway of the 5-HT4 receptors located on the cholinergic neurons towards the circular muscle layer in pig stomach was investigated by analysis of acetylcholine release. Circular muscle strips were prepared from pig proximal stomach and tritium outflow, induced by electrical field stimulation, was studied as a marker for acetylcholine release after incubation with [3H]-choline. The PDE4-inhibitor roflumilast concentration-dependently (0.1–1µM) enhanced the facilitating effect of a submaximally effective concentration of the 5-HT4 receptor agonist prucalopride (0.01µM) on electrically induced acetylcholine release. Roflumilast (0.3µM) enhanced acetylcholine release per se but in the combined presence of roflumilast and prucalopride, acetylcholine release was enhanced more than the sum of the effect of the 2 compounds alone. The 5-HT4 receptor agonist velusetrag concentration-dependently (0.01–0.1µM) enhanced acetylcholine release; the effect of the minimally effective concentration (0.01µM) was significantly enhanced by 1µM of the PDE4-inhibitor rolipram, again to a level higher than the sum of the effect of the 2 compounds alone. The synergistic effect between 5-HT4 receptor agonists and PDE4-inhibitors demonstrates that the intracellular pathway of the 5-HT4 receptors located on cholinergic neurons towards pig gastric circular muscle is controlled by PDE4. Combining a 5-HT4 receptor agonist with a PDE4-inhibitor might thus enhance its gastroprokinetic effect.