Corticosterone, Adrenal, and the Pituitary-Gonadal Axis in Neonatal Rats: Effect of Maternal Separation and Hypoxia
Bibliographic record
Abstract
Hypoxia, a common stressor in prematurity, leads to sexually dimorphic, short- and long-term effects on the adult hypothalamic-pituitary-adrenal (HPA) and hypothalamic-pituitary-gonadal (HPG) axes. We hypothesized that these effects are due to stress-induced increases in testosterone during early postnatal life. We evaluated this phenomenon by systematically assessing the short-term effects of normoxic or hypoxic separation on male and female pups at birth, postnatal hours (H) 2, 4, and 8, and postnatal days (PD) 2 to 7. Our findings were (a) hypoxic separation led to a large increase in plasma corticosterone from 4H-PD4, (b) neither normoxic nor hypoxic separation affected critical adrenal steroidogenic pathway genes; however, a significant decrease in baseline Cyp11a1, Mc2r, Mrap, and Star adrenal expression during the first week of neonatal life confirmed the start of the adrenal stress hyporesponsive period, (c) a luteinizing hormone/follicle-stimulating hormone-independent increase in plasma testosterone occurred in normoxic and hypoxic separated male pups at birth, (d) testicular Cyp11a1, Lhcgr, and Star expression was high at birth and decreased thereafter suggesting a hyporesponsive period in the testes, and (e) elevated estrogen in the early neonatal period occurred independently of gonadotropin stimulation. We conclude that a large corticosterone response to hypoxia during the first 5 days of life occurs as an adaptation to neonatal stress, that the testosterone surge during the first hours after birth occurs independently of gonadotropins but is associated with upregulation of the steroidogenic pathway genes in the testes, and that high postnatal estrogen production also occurs independently of gonadotropins.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".