Regulation of cardiac oxytocin system and natriuretic peptide during rat gestation and postpartum
Bibliographic record
Abstract
We have recently uncovered the presence of an oxytocin system in the heart and found that oxytocin is a physiological regulator of atrial natriuretic peptide (ANP), a diuretic, natriuretic and vasodilator cardiac hormone. However, dynamic changes in these systems during gestation, when mechanisms of volume and pressure homeostasis are altered, are not clear. Accordingly, ANP, oxytocin and oxytocin receptors were evaluated in rat hearts and plasma at three stages of gestation (7, 14 and 21 days) and at 2 and 5 days postpartum. Compared with non-pregnant controls, plasma ANP was elevated in mid-gestation, but significantly decreased at term (21 days), to increase again postpartum. Right and left atrial ANP mRNA levels were not altered throughout gestation but increased by 1.5- to 2-fold postpartum (P<0.01). At term, ANP content in right (8.7+/-1.2 vs 12.7+/-1.1 micro g/mg protein, P<0.04) and left (3.5+/-0.6 vs 8.5+/-2.0 micro g/mg protein, P<0.01) atria increased. These findings imply that decreased plasma ANP at term results from inhibition of release rather than decreased synthesis. In parallel, oxytocin, a stimulator of ANP release, decreased in left atria at day 7 to 50% of non-pregnant levels and remained low throughout gestation. Oxytocin receptor mRNA increased in left atria at 7 and 14 days of gestation by 2- and 5-fold respectively, but decreased at 21 days to lower than non-pregnant levels to increase again (3-fold) postpartum. The changes in oxytocin receptor expression at term and postpartum paralleled oxytocin receptor protein determined by Western blot. These results imply that pregnancy is associated with dynamic changes in the cardiac oxytocin system (peptide and/or receptors), which may influence natriuretic peptide release. Together, these peptides would act on their receptors in the heart, vasculature and kidneys to maintain vascular tone and renal function throughout gestation and postpartum.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".