Profiling of systemic and brain steroids in male songbirds: Seasonal changes in neurosteroids
Bibliographic record
Abstract
Abstract Steroids are secreted by the gonads and adrenal glands into the blood to modulate neurophysiology and behaviour. In addition, the brain can metabolise circulating steroids and synthesise steroids de novo. Songbirds show high levels of neurosteroid synthesis. In the present study, we developed and validated a liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) assay for the measurement of 10 steroids in whole blood, plasma and microdissected brain tissue (1‐2 mg) of song sparrows. Our assay is highly accurate, precise, specific and sensitive. Moreover, the liquid‐liquid extraction is fast, simple and effective. We quantified steroids in the blood and brain of wild male song sparrows in both breeding and non‐breeding seasons. As expected, systemic androgen levels were higher in the breeding season than in the non‐breeding season. Brain androgens were detectable only in the breeding season; androstenedione and 5α‐dihydrotestosterone levels were up to 20‐fold higher in specific brain regions than in blood. Oestrogens were not detectable in blood in both seasons. Oestrone and 17β‐oestradiol were detectable in brain in the breeding season only (up to 1.4 ng g ‐1 combined). Progesterone levels in several regions were higher in the non‐breeding season than the breeding season, despite the lack of seasonal changes in systemic progesterone. Corticosterone levels in the blood were higher in the breeding season than in the non‐breeding season but showed few seasonal differences in the brain. In general, the steroid levels presented here are lower than those in previous reports using immunoassays, because of the higher specificity of mass spectrometry. We conclude that (i) brain steroid levels can differ greatly from circulating steroid levels and (ii) brain steroid levels show region‐specific seasonal patterns that are not a simple reflection of circulating steroid levels. This approach using ultrasensitive LC‐MS/MS is broadly applicable to other species and allows steroid profiling in microdissected brain regions.
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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".