Leptin increases FA oxidation in lean but not obese human skeletal muscle: evidence of peripheral leptin resistance
Bibliographic record
Abstract
The adipocyte-derived hormone leptin has been shown to acutely increase fatty acid (FA) oxidation and decrease esterification in resting rodent skeletal muscle. However, the effects of leptin on human skeletal muscle FA metabolism are completely unknown. In these studies, we have utilized an isolated human skeletal muscle preparation combined with the pulse-chase technique to measure FA metabolism with and without leptin in lean and obese human skeletal muscle. Under basal conditions (in the absence of leptin), muscle from the obese demonstrated significantly elevated levels of total FA uptake (+72%, P = 0.038) and enhanced rates of FA esterification into triacylglycerol (+102%, P = 0.042) compared with lean subjects. In the presence of leptin, lean muscle had elevated rates of endogenous (+103%, P = 0.01) and exogenous (+150%, P = 0.03) palmitate oxidation. When the ratio of esterification to exogenous oxidation was examined, leptin reduced this ratio (-47%, P = 0.032), demonstrating the increased partitioning of FA toward oxidation and away from storage. Contrary to these findings in lean muscle, leptin had no effect on FA metabolism in skeletal muscle of the obese. This study provides the first evidence that leptin increases FA oxidation in skeletal muscle of lean, but not obese humans, thus demonstrating the development of leptin resistance in obese human skeletal muscle.
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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) | 0.002 | 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".