Intragastric fructose administration interacts with emotional state in homeostatic and hedonic brain regions.

Background: Interoceptive properties of food may influence emotional state and its neural basis, as shown for fatty acids but remains unstudied for carbohydrates. Objectives: To study the effects of fructose and its interaction with sad emotion on brain activity in homeostatic and hedonic regions and investigate whether gut hormone responses can explain effects. Design: In 15 healthy subjects, brain activity for 40min after intragastric infusion of fructose (25g) or water was recorded using a cross-over pharmacological magnetic resonance imaging (phMRI) paradigm. Sad or neutral emotional states were induced by classical music and emotional facial expressions. Emotional state was assessed using the Self-Assessment Manikin. Blood samples were taken to assess gut hormone levels. Brain responses to fructose versus placebo, sad versus neutral emotion, and their interaction were analyzed over time in a single mask of a priori defined regions of interest at a voxel-level threshold of pFWEcorrected  <0.05. Effects on emotion and hormones were tested using linear mixed models. Results: No main effects of fructose, emotion, or fructose-by-emotion interaction on emotional ratings were observed. Main effects of fructose, emotion and aninteraction effect were found on brain activity (medulla, midbrain, hypothalamus, basal ganglia, anterior insula, orbitofrontal cortex, anterior cingulate cortex and amygdala). An increase in circulating GLP-1 after fructose in neutral emotion was abolished during sad emotion (fructose-by-emotion-by-time, p =0.041). Ghrelin levels were higher in sad emotion (time-by-emotion, p =0.037). Conclusions: Emotional state interacts with brain and endocrine responses to intragastric infusion of 25 g of fructose, however such an effect was not found at behavioral level. Trial registration: ClinicalTrials.gov identifier: NCT02946983.