Thyroid Hormones Influence the Development of Hippocampal Glucocorticoid Receptors in the Rat: A Mechanism for the Effects of Postnatal Handling on the Development of the Adrenocortical Stress Response
Bibliographic record
Abstract
The role of thyroid hormones on the development of intracellular glucocorticoid receptor concentrations was examined in the hippocampus, hypothalamus, and pituitary of the rat. Adult animals, administered triiodothyronine (T3; 1.0 micrograms/g body weight) on days 1, 2, and 4 of life or thyroxine (T4; 2.5 micrograms/g body weight) on days 1 and 2 of life, had significantly elevated glucocorticoid receptor concentrations in the hippocampus, but not in hypothalamus or pituitary. Adult animals treated with propylthiouracil (PTU; 0.2% in the mother's food), a thyroid hormone synthesis inhibitor, for the first 2 weeks of life showed decreased glucocorticoid receptor concentrations in hippocampus, but not in hypothalamus or pituitary. We then examined whether thyroid hormones might mediate the effects of early stimulation on the development of hippocampal glucocorticoid receptor concentrations. Animals that were handled for 15 min daily (Ha) for the first 2 weeks of life showed increased hippocampal glucocorticoid receptor concentrations as adults compared to nonhandled (NHa) controls. PTU administration blocked the effects of handling, such that Ha/PTU animals showed hippocampal glucocorticoid receptor concentrations that were indistinguishable from those of NHa animals. In contrast, corticosterone administration over the first 2 weeks of life had no effect on adult hippocampal glucocorticoid receptor concentrations. These data suggest that thyroid hormones mediate, in part at least, the development of glucocorticoid receptor concentrations in the hippocampus and that this effect occurs independently of their effects on corticosterone titers.
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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) | 0.001 | 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".