Preoperative μ-opioid receptor availability predicts weight loss following bariatric surgery
Bibliographic record
Abstract
Abstract Background Bariatric surgery is the most effective method for weight loss in morbid obesity. There is significant individual variability in the weight loss outcomes, yet factors leading to postoperative weight loss or weight regain remain elusive. Alterations in the µ-opioid receptor (MOR) and dopamine D 2 receptor (D 2 R) systems are associated with obesity, appetite control, and reward processing. The magnitude of initial brain receptor system perturbation is a plausible predictor of long-term surgical weight loss outcomes. The aim was to test this hypothesis by measuring obese subjects’ MOR and D 2 R availability with positron emission tomography (PET) preoperatively before bariatric surgery and then assessing their weight development association with regional MOR and D 2 R availabilities at 2-year follow-up. Methods We studied 19 morbidly obese women (mean BMI 40, mean age 43) scheduled to undergo bariatric surgery, i.e. Roux-en-Y gastric bypass or sleeve gastrectomy, according to their standard clinical treatment. Preoperative MOR and D 2 R availabilities were measured using PET with [ 11 C]carfentanil and [ 11 C]raclopride, respectively. Subject weight was recorded at 3, 6, 12, and 24 months after surgery. Radiotracer binding potentials ( BP ND ) were extracted and correlated with patient weight at different time points. ROIs were delineated in the striatum and in limbic and paralimbic components of the emotion and reward networks. Results MOR availabilities were not correlated with preoperative weight. MOR availabilities in the amygdala ( r = −0.54), insula ( r = −0.46), ventral striatum ( r = −0.48) and putamen ( r = −0.49) were associated with subject weight at 3 months. Significant association was found in the amygdala at 6 months ( r = −0.53), 12 ( r = −0.49), and 24 months ( r = −0.50). D 2 R availabilities were associated with neither preoperative weight nor weight loss at any follow-up time point. Conclusions To our knowledge, this is the first study to demonstrate that neuroreceptor markers prior to bariatric surgery in patients with morbid obesity are associated with the postoperative weight loss. Preoperative MOR availability in the amygdala was associated with long-term postoperative weight development after surgery suggesting that postoperative weight regain may derive from dysfunction in the opioid system. Postoperative weight loss outcomes after bariatric surgery may be partially predicted based on preoperative receptor availability opening up new potential for treatment possibilities. Clinical Trials Registration SleevePET2, NCT01373892 , http://www.clinicaltrials.gov
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".