Striatal dopamine D2/3 receptor availability increases after long-term bariatric surgery-induced weight loss.

Abstract In several studies reduced striatal dopamine D 2/3 receptor (D 2/3 R) availability was reported in obese subjects compared to lean controls. Whether this is a reversible phenomenon remained uncertain. We previously determined the short-term effect of Roux-en-Y gastric bypass surgery (RYGB) on striatal D 2/3 R availability (using [ 123 I]IBZM SPECT) in 20 morbidly obese women. Striatal D 2/3 R availability was lower compared to controls at baseline, and remained unaltered after 6 weeks, despite significant weight loss. To determine whether long-term bariatric surgery-induced weight loss normalizes striatal D 2/3 R binding, we repeated striatal D 2/3 R binding measurements at least 2 years after RYGB in 14 subjects of the original cohort. In addition, we assessed long-term changes in body composition, eating behavior and fasting plasma levels of leptin, ghrelin, insulin and glucose. Mean body mass index declined from 46±7 kg/m 2 to 32±6 kg/m 2 , which was accompanied by a significant increase in striatal D 2/3 R availability ( p =0.031). Striatal D 2/3 R availability remained significantly reduced compared to the age-matched controls (BMI 22±2 kg/m 2 ; p =0.01). Changes in striatal D 2/3 R availability did not correlate with changes in body weight/fat, insulin sensitivity, ghrelin or leptin levels. Scores on eating behavior questionnaires improved and changes in the General Food Craving Questionnaire - State showed a borderline significant correlation with changes in striatal D 2/3 R availability. These findings show that striatal D 2/3 R availability increases after long-term bariatric-surgery induced weight loss, suggesting that reduced D 2/3 R availability in obesity is a reversible phenomenon.