Muscle protein synthesis, degradation and the effect of mTORC1, after resistance exercise (1163.7)
Bibliographic record
Abstract
We aimed to measure mTORC1 signaling, rates of muscle protein synthesis (MPS), and proteasome activity after acute resistance exercise (REx). A second aim was to determine whether mTORC1 signaling impacted MPS in late recovery. Rats (8 m.o. FBN hybrids) underwent unilateral hindlimb stimulation that eccentrically contracted the tibialis anterior (TA). All measures in the stimulated TA were expressed relative to the contralateral control TA. TA muscles were collected at 1.5, 3, 6, 18, and 36 h after REx, and at 3 and 18 h after REx plus rapamycin treatment to block mTORC1 activity. There was a robust activation of mTORC1, whereby phosphorylation of S6K1 (T389) peaked at 3 h (134±22‐fold inc.) and returned to baseline by 18 h; phosphorylation of S6 (S240/244) peaked at 6 h (26±4‐fold inc.). MPS peaked at 6 h (67±31% inc.) before gradually declining toward baseline through 36 h. Principal proteasome activities, 26S and 20S beta5, tended to decrease (~15‐20% at 6‐12 h), and then increase at later time points (~15‐20% above rest at 18‐36 h). Interestingly, rapamycin treatment, while completely blocking increases in p‐S6K1, only partially blocked the elevation in MPS at 18 h. In summary, REx stimulated a large increase in mTORC1 signaling and a moderate sustained increase in MPS, and inhibiting mTORC1 did not fully abolish the MPS effect at 18 h. Further, for the first time, we have directly measured proteasome activity after REx. Grant Funding Source : Supported by NSERC and Veteran Affairs (RR&D Merit Grant E7766‐R)
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| 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 | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".