Oxytocin reduces satiety scores without affecting the volume of nutrient intake or gastric emptying rate in healthy subjects

Background Oxytocin is expressed throughout the gastrointestinal tract and is released in response to a fatty meal. Administration of an oxytocin receptor antagonist prolongs the gastric emptying rate. The aim of this study was to examine the effect of oxytocin on gastric accommodation, gastric emptying time, and satiety after food intake. Methods Ten healthy subjects participated in a slow satiety drinking test with a liquid meal. Every 5 min the subjects scored their sensation of satiety using a visual analogue scale (VAS) until maximum satiety was reached and the amount of liquid intake was determined. Twelve subjects participated in a gastric emptying test. They were given a standardized meal containing 20 radio-opaque markers, after which fluoroscopy was performed and VAS was scored every hour. Both tests were performed four times during infusions of saline and three different oxytocin concentrations. Blood was collected for oxytocin concentration measurements. Key Results There were no differences in the volume of nutrient intake at maximum satiety between the three doses of oxytocin and saline. However, lower satiety scores at maximum satiety were seen after oxytocin infusion (P = 0.031), with 40 mU min-1 being the most effective dosage (P = 0.013), and this was also true 30 min after finishing the meal (P = 0.032). There was no difference in gastric emptying time between saline and oxytocin. The oxytocin concentration in plasma was increased proportional to the oxytocin infusions. Conclusions & Inferences Infusion of oxytocin reduces satiety without affecting the volume of nutrient intake or gastric emptying in healthy subjects.