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 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) | 0.001 | 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".