Mesolimbic opioid-dopamine interaction is disrupted in obesity but recovered by weight loss following bariatric surgery
Bibliographic record
Abstract
Abstract Background Obesity is a growing burden to health and economy worldwide. Obesity is associated with central μ-opioid receptor (MOR) downregulation, and the interaction between MOR and dopamine D 2 receptor (D 2 R) system in the ventral striatum is disrupted among obese subjects. Weight loss recovers MOR function, but it remains unknown whether it also recovers aberrant opioid-dopamine interaction. Here we addressed this issue by studying subjects undergoing surgical weight loss (bariatric surgery) procedure. Methods We recruited 20 healthy non-obese (mean BMI 22) and 25 morbidly obese women (mean BMI 41) eligible for bariatric surgery. Brain MOR and D 2 R availability was measured using positron emission tomography (PET) with [ 11 C]carfentanil and [ 11 C]raclopride, respectively. Either Roux-en-Y gastric bypass or sleeve gastrectomy was performed to obese subjects according to standard clinical treatment. 21 obese subjects participated in the postoperative PET scanning six months after bariatric surgery. Results In the control subjects, MOR and D 2 R availabilities were associated in the ventral striatum ( r = .62) and dorsal caudate ( r = .61). Preoperatively, the obese subjects had disrupted association in the ventral striatum ( r = .12) but unaltered association in dorsal caudate ( r = .43). The association between MOR and D 2 R availabilities in the ventral striatum was recovered ( r = .62) among obese subjects following the surgery-induced weight loss (mean total weight loss 22 %). Conclusions Bariatric surgery and concomitant weight loss recovers the interaction between MOR and D 2 R in the ventral striatum in the morbidly obese. Consequently, the dysfunctional opioid-dopamine interaction in the ventral striatum is likely associated with an obese phenotype and may mediate excessive energy uptake. Striatal opioid-dopamine interaction provides a feasible target for pharmacological and behavioural interventions for treating obesity. 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 | 0.000 |
| 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".