The oxytocin/vasopressin receptor antagonist atosiban delays the gastric emptying of a semisolid meal compared to saline in human

Background: Oxytocin is released in response to a meal. Further, mRNA for oxytocin and its receptor have been found throughout the gastrointestinal (GI) tract. The aim of this study was therefore to examine whether oxytocin, or the receptor antagonist atosiban, influence the gastric emptying. Methods: Ten healthy volunteers (five men) were examined regarding gastric emptying at three different occasions: once during oxytocin stimulation using a pharmacological dose; once during blockage of the oxytocin receptors (which also blocks the vasopressin receptors) and thereby inhibiting physiological doses of oxytocin; and once during saline infusion. Gastric emptying rate (GER) was assessed and expressed as the percentage reduction in antral cross-sectional area from 15 to 90 min after ingestion of rice pudding. The assessment was performed by real-time ultrasonography. At the same time, the feeling of satiety was registered using visual satiety scores. Results: Inhibition of the binding of endogenous oxytocin by the receptor antagonist delayed the GER by 37% compared to saline (p=0.037). In contrast, infusion of oxytocin in a dosage of 40 mU/min did not affect the GER (p=0.610). Satiation scores areas in healthy subjects after receiving atosiban or oxytocin did not show any significant differences. Conclusion: Oxytocin and/or vasopressin seem to be regulators of gastric emptying during physiological conditions, since the receptor antagonist atosiban delayed the GER. However, the actual pharmacological dose of oxytocin in this study had no effect. The effect of oxytocin and vasopressin on GI motility has to be further evaluated.