156-OR: Central Neural Processing of Sweet Taste Is Altered following Bariatric Surgery

Bariatric surgery causes marked changes in eating behavior, including reduced preference for highly sweet foods. No studies have addressed the brain response to receipt of this primary taste modality following weight loss surgery. Eighteen women (BMI 47.5±7.6 kg/m², age 43.1±10.2 y) rated perceived intensity and liking of sucrose solutions (0, 0.1, 0.4, 0.86 & 1.M) in a three-block randomized design, and underwent functional magnetic resonance imaging (fMRI) to assess brain responses to 0.40 M and 0.M sucrose sprayed onto the tongue relative to water (14 sucrose and 34 water trials in two 5:52 min long scans) , before and after bariatric surgery-induced weight loss. Eight women underwent Roux-en-Y and had sleeve gastrectomy. The post-surgery visit occurred 4.7 months (range 3-9) following the pre-surgery assessment. BMI was significantly reduced to 38.0±7.8 kg/m². There was no effect of weight loss on rated sucrose solution intensity. However, post-surgical “preferred sweetness” of the test solutions was significantly lower (0.53±0.12 vs. 0.22±0.M; p<0.008) . Across the whole sample (pre- and post-surgery) , both sucrose concentrations relative to water activated bilateral insula and lateral frontal/orbitofrontal areas (p<0.001, k=5) . However, only 0.4M sucrose elicited the left nucleus accumbens (NAc) response (p_FWE=0.005, k=17, family wise error-corrected within a bilateral NAc mask) . Pre-surgery activations included the anterior cingulate cortex (ACC) and bilateral insula as well as NAc (left: p=0.001, k=33; right p=0.009, k=17) . Post-surgery activations were present only in the ACC and bilateral insula. NAc responses were significantly greater pre-surgery relative to post-surgery (p_FWE=0.026, k=6) . These data strongly suggest that bariatric surgery significantly affects central neural processing of sweet taste. While salience-assigning ACC and insula responses did not differ, nucleus accumbens region coding reward responded less post-surgically.