Effect of serotonin on bethanechol-stimulated gastric pepsin secretion in dogs

The effect of serotonin on bethanechol-stimulated gastric pepsin secretion was evaluated with regard to dose-response kinetics and receptor mediation. A low dose of exogenous serotonin produced a stimulation (0.5 microgram/kg/min), whereas inhibition was found for higher doses (5-10 micrograms/kg/min). The inhibition was non-competitive and could be significantly counteracted by beta-adrenergic blocking drugs. This study confirms results obtained during pentagastrin stimulation and supports the concept that serotonin acts via sympathetic nerves to release noradrenaline.