Influence of Intragastric Fatty Acid Infusion on Behavioral Responses to Positive Emotion Induction in Normal Weight Subjects

This study aims at the possible effect of subliminal intragastric administration of fatty acids on responses to positive emotion induction, based on our earlier findings that subjective administration of fatty acid decreases neural responses to negative mood induction (Van Oudenhove et al, J Clin Invest 2011). After screening for exclusion criteria and the participants sign the informed consent form, an intravenous catheter is placed in the forearm, and a naso-gastric tube inserted through the nose. Then the test subject is connected to the equipment in order to record the activity of the autonomic nervous system, via three electrocardiogram electrodes. By using the nasogastric tube we serve a fatty acid solution (Dodecanoic acid, "fatty acid" condition) or a physiological saline solution ( "control" condition) intragastrically. The intragastric administration of low doses of this food ingredient has already been used in several previous studies by our research group and has proven perfectly safe. A positive or neutral emotional state will be induced by the combination of looking at emotional facial expressions and listening to classical music pieces that were previously validated for this purpose; This combination of incentives has already been used in previous studies of our research group. Responses will be measured by means of validated self-report scales and measurements of the vagal tone. We also take blood samples on a regular basis by the intravenous catheter for determination of gastrointestinal hormones, given our hypothesis that this may explain the effect on emotions. After removal of the nasogastric tube, the influence of subliminal administration of fatty acids and emotional state on food intake measured by means of a validated and previously drink test used in which participants "ad libitum" to drink a chocolate milkshake while the emotion-induction by means of classical music pieces continue. Finally, the intravenous catheter is removed.