Role of Pituitary POMC-Peptides and Insulin-Like Growth Factor II in the Developmental Biology of the Adrenal Gland
Bibliographic record
Abstract
During fetal life, it is critical that there is coordinate regulation of the growth, zonation and differentiation of the fetal adrenal cortex to ensure that cells in key tissues and organs are exposed in a programmed temporal sequence to the actions of glucocorticoids. Glucocorticoids are essential for maturation of key target organs before birth, including the lung, brain, liver, gut, kidney and adrenal, and the prepartum increase in glucocorticoid synthesis and secretion by the fetal adrenal gland is critical for the successful transition to postnatal life. It is also evident that premature or abnormal exposure of embryonic or fetal tissues to glucocorticoids during critical windows of development can irreversibly alter the programmed development of organ systems. Premature or abnormal exposure of the fetus to excess glucocorticoids may occur either as a consequence of endogenous stimulation of the fetal hypothalamo-pituitary-adrenal axis (HPAA) or as a consequence of exposure to exogenous glucocorticoids in a therapeutic context. Administration of synthetic glucocorticoids to women at risk of preterm labour, for example, is a routine clinical practice designed to improve respiratory function and neonatal outcome. It is clearly important to understand what endogenous factors regulate the growth and functional maturation of the adrenal cortex during development and the consequent likelihood of exposure of developing tissues to excess corticosteroids. To date, investigations have centred on the role of ACTH 1-39 in the stimulation of adrenal growth and steroidogenesis in long gestation species, such as the primate and sheep, where maturation and differentiation of organ systems occurs predominantly before birth. In this review, we will focus on the evidence that in addition to ACTH 1-39, other pro-opio-melanocortin (POMC) derived peptides, which are synthesized, processed and secreted by the fetal pituitary, play a role in the coordinate regulation of the specific phases of growth and functional development of the fetal adrenal gland in vivo. We will discuss our recent findings on the direct in vivo actions of N-POMC 1-77 and separately, insulin like growth factor II (IGF-II), as adrenal growth factors. These studies provide an understanding of the separate regulatory mechanisms which control activation of adrenal growth and stimulation of adrenal steroidogenesis in the late gestation fetus.
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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) | 0.001 | 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) | 0.000 | 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".