A Study of Insulin‐like Growth Factor‐I Receptor Immunoreactivity in the Supraoptic Nucleus of Young and Old Female B6D2F1 Mice
Bibliographic record
Abstract
Insulin‐like Growth Factor‐I (IGF‐I) is a critical hormone that regulates both development and aging with its fluctuating expression throughout the lifespan. Multiple studies have demonstrated that IGF‐I levels in the mammalian brain decline with age. However, without simultaneously tracking tissue sensitivity to IGF‐I, its net biological effect remains undefined. Taking IGF‐I receptor (IGF‐IRc) immunoreactivity as a measure of tissue sensitivity, our study measures its levels in the supraoptic nucleus (SON) of the hypothalamus. With its central location, the SON is the major arbiter of posterior pituitary activity, and IGF‐I action in the SON specifically influences vasopressin release, and provides neuroprotection. Current results from SON in ad libitum fed mice show a significant reduction in percentage of IGF‐IRc‐positive cells from 44% in young (5 week old) to 36% in old (22 month old). This reduced sensitivity of SON IGF‐I with age, parallels the declining IGF‐I levels in other brain areas and implies that the overall biological action of IGF‐I on the aging phenotype is reduced. Whether this reduction is an adaptive response to the aging process or a causative factor resulting in the aged phenotype remains to be established. Supported by NIH AG 19145‐04 and BioTime, Inc., Emeryville, CA.
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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 | 0.002 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".