Effect Of Endogenous And Synthetic Sex Hormones On Myoblast Function Following Electrical Stimulation.
Bibliographic record
Abstract
Endogenous sex hormones across the menstrual cycle (MC) may influence exercise-induced muscle damage and the subsequent repair and regenerative response. Furthermore, despite wide-spread oral contraceptive (OC) use in women, the repair response in OC users is still unknown, as the effect of synthetic hormones ethinyl estradiol (EE) and progestins on the myogenic program has not yet been investigated. PURPOSE: To investigate the impact of endogenous (natural) and exogenous (synthetic) hormone exposure on myoblast proliferation, differentiation, and migration in C2C12 mouse myoblasts. Our secondary aim was to explore the effect of these hormones on the response to electrical pulse stimulation (EPS). METHODS: C2C12 myoblasts were cultured with the following hormones: 17β-estradiol (E2) and progesterone versus EE and first- to fourth-generation progestins [medroxyprogesterone acetate (MPA), levonorgestrel (LNG), desogestrel (DESO), and drospirenone (DRP), respectively] and were assessed for their cellular response (proliferation, differentiation, migration, protein expression) before and after EPS. RESULTS: Cell proliferation was significantly decreased with the addition of progesterone greater than 1.5 ng/ml [3 ng/ml: -18% (p < 0.001), 10 ng/ml: -17% (p < 0.001), 20 ng/ml: -22% (p < 0.001), 40 ng/ml: -26% (p < 0.001) compared to control] and was differentially affected by OC hormones based on generation [MPA: -10.7%, LNG: -9.7%, DESO: +4.3%, and DRP: +4.0% compared to control]. Cell migration and differentiation were unaffected by physiological doses of E2 or progesterone alone but decreased with the addition of progesterone to replicate MC phase conditions [+20% in mid-luteal phase compared to early follicular phase, p = 0.03] or progestin in OC formulations [MPA: -28% (p < 0.001), LNG: -24% (p < 0.001), DESO: -27% (p < 0.001), DRP: -22% (p < 0.001) compared to EE alone]. CONCLUSION: Our results indicate that circulating sex hormones are potent effectors of skeletal muscle cell function. The influence of endogenous and exogenous hormones on the muscle response is still poorly understood, but we speculate that progestins play a larger role than natural or synthetic estrogen on the muscle cell response to EPS.
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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".