Effects of estrogen receptor activation on post-exercise muscle satellite cell proliferation
Bibliographic record
Abstract
This study investigated the role of estrogen receptor activation on total and proliferating satellite cells following running exercise in rats, by using an estrogen receptor-alpha (ER-α) specific agonist, 4,4,4 (4-Propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT). PPT is the first ER-α specific agonist (Stauffer et al 2000) which binds the ER-a subtype with a 410-greater affinity than ER-β (Stauffer et al 2000). Previous studies have demonstrated that estrogen can augment muscle satellite cell numbers following exercise (Enns and Tiidus, 2008) and that this augmentation may be due to mechanisms activated via estrogen receptors that can influence total, proliferating, and differentiating satellite cell numbers (Enns et al 2008). Ovariectomised female rats (n = 64) were divided into four groups: sham, estrogen (0.25 mg estrogen), agonist (PPT), and estrogen plus PPT. Each group was further divided into exercisers and controls (non-exercisers). PPT administration commenced 2 days after estrogen implantation and continued for 6 days. After 7 days of estrogen exposure, exercisers ran intermittently for 90 minutes (17m/min, -13.5 degree grade). Soleus and white vastus muscles were removed 72 hours post-exercise and immunohistochemically stained for total (pax7) and activated (MyoD) satellite cells. Severity of muscle damage was assessed indirectly by measuring betaglucuronidase activity. The results revealed that there were significant increases (p < 0.05) in fibers staining positive for total (pax7) and activated (MyoD) satellite cells when compared to shams in both the soleus and white vastus muscles. However, there was no significant difference (p > 0.05) observed between the treatment conditions supplemented with estrogen, PPT, and estrogen plus PPT. Augmented increases observed in muscle satellite cells post-exercise in the PPT supplemented group suggests that their activation is an estrogen receptormediated process. Due to no significant difference (p > 0.05) observed between PPT- and estrogen-mediated activation of ER-α receptors, ER-α is implicated as the receptor responsible for most, if not all, of the activation of satellite cell activity when induced by estrogen.
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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".