Exercise is required to maintain unacylated ghrelin response in adult male rat skeletal muscle, regardless of dietary fat consumption
Bibliographic record
Abstract
Unacylated ghrelin (unAG) stimulates fatty acid oxidation (FAO) in isolated male rat skeletal muscle. However, 6 weeks of high-fat feeding results in "ghrelin resistance," or loss of this effect. Recent work has indicated that sedentary behavior may be a main contributor to the loss of skeletal muscle unAG response, potentially representing an early disruption in lipid metabolism in the development of metabolic disease. Therefore, the objective of this study was to investigate whether exercise is required to maintain the stimulatory effect of unAG on FAO in skeletal muscle and if the exercise intensity needed is dependent on dietary fat intake. Male rats were fed either a low- or high-fat diet for 6 weeks while remaining sedentary, or performing low- or high-intensity exercise. Soleus muscle strips were isolated and assessed for their ability to respond to unAG by increasing FAO. High-intensity exercise preserved unAG response under both low-fat and high-fat dietary conditions, an effect not observed in sedentary or low-exercise groups. Additional soleus muscle strips were collected from all groups to assess the activation of the AMP-activated protein kinase-acetyl-CoA carboxylase axis and Ca2+ signaling in response to unAG; however, these pathways were not found to be significantly activated. Exercise also increased corticotropin-releasing factor 2 receptor content, the putative receptor through which unAG signals in skeletal muscle, whereas high-fat feeding had an overall effect to reduce it. However, unAG treatment did not activate cAMP/protein kinase A signaling. These findings demonstrate a protective role of exercise in maintaining skeletal muscle unAG response, although mechanisms remain to be fully elucidated. SIGNIFICANCE STATEMENT: Unacylated ghrelin stimulates fatty acid oxidation and protects insulin response in skeletal muscle; this response is lost with physical inactivity. We demonstrate that high-intensity exercise preserves this response, potentially due to changes in corticotropin-releasing factor 2 receptor content.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".