Delay in post‐ovariectomy estrogen replacement negates post‐exercise estrogen augmentation of muscle satellite cell population in rats (1163.23)
Bibliographic record
Abstract
17β‐Estradiol (E2) enhances activation, proliferation and differentiation of muscle satellite cells (SCs) following exercise via activation of estrogen receptor‐α (ER) and phosphatidylinositol 3‐kinase (PI3K) signaling. Supplementation of E2 through hormone replacement has been shown to ameliorate muscle atrophic effects of menopause in women. Delay in post‐menopause E2 replacement in humans or following ovariectomy in rodents has resulted in negation of positive health or regenerative effects of E2 on various tissues. To determine if delay in E2 replacement influenced E2 effects on skeletal muscle, 64, nine‐week old, ovariectomized Sprague‐Dawley rats were divided into eight groups based on: E2 status (0.25 mg estrogen pellet or sham), exercise status (90 min run @ 17 m/min, ‐13.5° or unexercised) and E2 replacement (“proximal”; E2 replacement within one week or “delayed”; eleven‐weeks following ovariectomy). Significant increases in total SCs were found in soleus muscle (immunofluorescent co‐localization of nuclei with Pax7) 72 hr following eccentric exercise ( p < 0.05). Only “proximal” estrogen‐replacement resulted in further enhancement in total muscle SCs in exercised rats ( p < 0.05). Delayed estrogen‐supplementation did not produce a further augmentation in post‐exercise SCs. This suggests the existence of a short window of opportunity where E2 replacement must commence following loss of endogenous estrogen production in order for benefits to skeletal muscle regeneration to manifest. Grant Funding Source : Supported 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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.004 | 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".