Triiodothyronine Nuclear Receptors in Liver, Brain and Lung of Neonatal Rats
Bibliographic record
Abstract
In this study we have examined the effect of neonatal hypothyroidism and triiodothyronine (T<sub>3</sub>) replacement therapy on the maximal binding capacity (MBC) and the affinity of T<sub>3</sub> receptors prepared from liver, brain and lungs. Rats were radiothyroidectomized at birth and administered T<sub>3</sub> or its placebo starting at 8 days of age. The thyroid state in normal, hypothyroid and hypothyroid T<sub>3</sub>-treated rats was assessed by serum determination of thyroxine, T<sub>3</sub> and by the measurement of the hepatic α-glycerophosphate dehydrogenase. The animals were sacrificed at 8, 16 or 24 days of age and the T<sub>3</sub> binding was estimated in isolated nuclei and in salt nuclear extracts. The MBC of the T<sub>3</sub> receptors was higher in the hypothyroid rats at all ages when it was determined in isolated nuclei, but not when was measured in nuclear extracts. At 8 days, the MBC had risen twofold or more in the receptors from brain (1.0 ± 0.37 vs. 0.4 ± 0.1 ng T<sub>3</sub>/mg DNA in controls) and from lungs (0.6 ± 0.25 vs. 0.3 ± 0.15 ng T<sub>3</sub>/mg DNA in controls), but was only slightly elevated in the hepatic receptor (0.62 ± 0.08 vs. 0.48 ± 0.15 ng T<sub>3</sub>/mg DNA in controls). At 16–24 days, the highest value of MBC was observed in the hepatic receptor (0.83 ± 0.04 vs. 0.41 ± 0.1 ng T<sub>3</sub>/mg DNA in controls) followed by the brain receptor (0.65 ± 0.03 vs. 0.35 ± 0.02 ng T<sub>3</sub>/mg DNA in controls), and that of lung (0.39 ± 0.07 vs. 0.20 ± 0.03 ng T<sub>3</sub>/mg DNA in controls). T<sub>3</sub> replacement therapy caused a marked diminution of the MBC of the hepatic receptor (0.54 ± 0.07 ng T<sub>3</sub>/mg DNA), but had little effect on brain and lungs. No changes in affinity were observed throughout the experiments. It has been concluded that the increase of MBC in hypothyroidism probably represents a protective mechanism which provides an adequate amount of T<sub>3</sub> to the cellular structure responsible for initiating the hormone action. T<sub>3</sub> replacement therapy restores the MBC to normal in receptors from tissues (liver) that bind especially T<sub>3</sub> from plasma, but not in tissues which need locally generated hormone to occupy their receptors (brain and lungs).
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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".