Estrogen replacement reduces PGHS-2-dependent vasoconstriction in the aged rat
Bibliographic record
Abstract
The reduction in estrogen in postmenopausal women contributes to an increase in vascular dysfunction. Models of aging have shown that this is due, in part, to increased prostaglandin H synthase (PGHS)-dependent vasoconstriction. We showed previously that inducible PGHS-2-dependent vasoconstriction is increased with aging. In the present study, we hypothesized that estrogen suppresses PGHS-2-dependent constriction in the aged rat. Isolated mesenteric arteries from placebo- or estrogen-treated, ovariectomized aged (24 mo) Fisher rats were assessed for endothelium-dependent relaxation in the absence or presence of PGHS inhibitors. PGHS inhibition (meclofenamate, 1 micromol/l) enhanced methacholine-induced relaxation only in the placebo group. Specific PGHS-2 inhibition (NS-398, 10 micromol/l) increased arterial relaxation to a greater extent than PGHS-1 inhibition (valeryl salicylate, 3 mmol/l). Estrogen prevented the PGHS-dependent constrictor effect but did not enhance nitric oxide-dependent relaxation in this model. PGHS-1 and endothelial nitric oxide synthase were not altered by estrogen, whereas PGHS-2 expression was decreased in the estrogen-replaced rats (P < 0.05). In summary, estrogen replacement improved vasodilation in aged rats by decreasing PGHS-dependent constriction.
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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) | 0.001 | 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".