OR19-04 Glucocorticoid Production in the Nervous and Immune Systems: Evidence for a Local HPA Axis Homolog
Bibliographic record
Abstract
Abstract Glucocorticoid Production in the Nervous and Immune Systems: Evidence for a Local HPA Axis Homolog The hypothalamic-pituitary-adrenal (HPA) axis is a critical stress response system in vertebrates. The hypothalamus secretes corticotropin-releasing hormone (CRH), which binds its receptor (CRH-R1) in the anterior pituitary. The anterior pituitary then secretes adrenocorticotropic hormone (ACTH), which binds its receptor (MC2R) in the adrenal glands and stimulates secretion of glucocorticoids into the bloodstream. Glucocorticoids are critical modulators of neural and immune system development. During early development (postnatal day (PND) 2 to 12), mice show decreased adrenal glucocorticoid secretion at baseline and in response to stressors, termed the stress hyporesponsive period (SHRP) (1). Traditionally, glucocorticoids have been thought to be synthesized only in the adrenal glands. However, recent evidence demonstrates that glucocorticoids are also produced in extra-adrenal tissues, such as the brain and lymphoid organs (2). This may be of particular importance during the SHRP, as local production allows glucocorticoid modulation of specific tissues and cells, without general effects throughout the organism. Importantly, the factors that regulate local glucocorticoid production remain unknown. To study the regulation of local glucocorticoid production, we examined whether mediators of the HPA axis are locally expressed at baseline and in response to an immune stressor. We assessed systemic and local glucocorticoid levels in neonatal (PND5) C57BL/6J mice 4hr after an immune challenge with lipopolysaccharide (50µg/kg i.p.) or vehicle control. We examined blood, microdissected brain regions (prefrontal cortex, hippocampus, hypothalamus), and lymphoid organs (thymus, spleen, bone marrow). A panel of 7 steroids was measured via liquid chromatography tandem mass spectrometry (LC-MS/MS). Gene expression of Crh, Crh-R1, Pomc, and Mc2r was quantified via qPCR. Preliminary data indicate that corticosterone was 2-fold higher in tissues than in blood after an immune stressor. The thymus expressed all genes of interest, supporting the existence of a local HPA axis “homolog” in the thymus. Brain, spleen and bone marrow expressed a subset of the genes of interest. These exciting data demonstrate that all the mediators of the HPA axis are locally expressed within the thymus, likely to regulate thymocyte development and reactivity. Greater understanding of local glucocorticoid production will provide crucial insight into neural and immune development and function. Reference: (1) Sapolsky et al., Brain Res Rev. 1986 11(1):65–76. (2) Taves et al., Endocrinology. 2015 156(2):511–522.
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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 | 0.002 |
| 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".