Pregnancy Decreases Oestrogen Receptor α Expression and Pyknosis, but not Cell Proliferation or Survival, in the Hippocampus
Bibliographic record
Abstract
Motherhood differentially affects learning and memory performance and this effect depends on reproductive experience. In turn, evidence suggests that the effects of oestradiol on learning and memory are mediated through binding to oestrogen receptors in the hippocampus and that this is related to hippocampal neurogenesis. The present study investigated the effect of pregnancy and reproductive experience on ERalpha expression throughout the hippocampus, as well as cell proliferation, new cell survival and cell death (as measured by pyknotic cells) in the granule cell layer of the hippocampus. Three groups of female Sprague-Dawley rats were used: virgin, primigravid and multigravid. All rats were injected with 5-bromo-2-deoxyuridine (BrdU; 200 mg/kg) on the afternoon of impregnation and at matched time-points in virgins. Rats were perfused either during early pregnancy (gestation day 1) or late pregnancy (gestation day 21) after BrdU injection. The results obtained show that, during late pregnancy, females, whether first or second pregnancy, have fewer ERalpha-positive cells in the CA3 region of the dorsal hippocampus than virgin females. In addition during early pregnancy, females have significantly fewer pyknotic cells in the granule cell layer than virgin females. There were no other differences between groups in the number of ERalpha-positive, BrdU-positive or pyknotic cells. Future studies will aim to investigate the mechanisms and consequences of the alteration in ERalpha expression in the hippocampus during late pregnancy, as well as the possible changes in ERbeta expression at this time.
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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 | 0.002 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".