Antioxidant Supplementation in Men Attenuates the Exercise-Induced Increase in mRNA Expression of PDK4 and IRF-1 Following Prolonged Cycling
Bibliographic record
Abstract
PURPOSE: We investigated the effects of antioxidant supplementation on skeletal muscle mRNA expression of genes involved in substrate metabolism (FOXO1, PDK4, and PPARγ), mitochondrial biogenesis (PGC-1α, and mitofusin2) and oxidative stress management (SOD2, GPX1, catalase, IRF-1, and JunB) in response to moderate intensity endurance exercise. METHODS: Following a placebo-controlled, double-blind, parallel, random design, 20 healthy, young, sedentary men performed two separate bouts of cycling for 90 min at 65% VO2max. The first bout occurred following 14 days of supplementation with placebo (PL), whereas the second bout occurred after 14 days of supplementation with either PL (n = 10) or antioxidants (ANT, n = 10). Muscle biopsies were taken from the vastus lateralis prior to and 3 h after exercise, and analyzed for the expression of the following genes: FOXO1, PDK4, PPARγ, PGC-1α, mitofusin2, SOD2, GPX1, catalase, IRF-1, and JunB. RESULTS: Exercise increased the mRNA expression of FOXO1 (4.7 fold, P < 0.001), PDK4 (10 fold, P < 0.001), PGC-1αα (16.2 fold, P < 0.001), mitofusin2 (50%, P < 0.001), SOD2 (50%, P = 0.027), GPX1 (41%, P = 0.017), IRF-1 (4.3 fold, P < 0.001), and JunB (23%, P < 0.001). ANT supplementation attenuated the exercise-induced increase in the absolute mRNA expression of PDK4 (−58%, P = 0.045) and the fold change of IRF-1 during the second exercise bout (−60%, P = 0.051). There was a 'second bout' effect, whereby changes in mRNA expression of some genes were apparent prior to and after the second bout of exercise, 2 weeks following the first bout, in both absolute expression (FOXO1 −30%, P = 0.035; mitofusin2 +72%, P < 0.001; SOD2 +60%, P = 0.001; and IRF−1 −29%, P = 0.034) and fold change due to exercise (FOXO1 −71%, P = 0.005; PDK4 −73%, P = 0.006; and JunB −48%, P = 0.038). CONCLUSIONS: Our results indicate that acute exercise up-regulates skeletal muscle mRNA expression of genes involved in substrate metabolism, mitochondrial biogenesis and oxidative stress management and that this is attenuated only in PDK4 and IRF-1 following ANT supplementation. In addition, we are the first to establish a second bout effect at the transcriptional level for genes involved in all three outcome measures. (This research was funded by NSERC)
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".