3β‐HSD in songbird brain: subcellular localization and rapid regulation by estradiol
Bibliographic record
Abstract
The enzyme 3β-hydroxysteroid dehydrogenase/Δ5-Δ4 isomerase (3β-HSD) catalyzes the conversion of dehydroepiandrosterone to androstenedione, thereby playing a key role in sex steroid synthesis. In peripheral tissues, 3β-HSD is membrane-bound, is present in both mitochondria and microsomes, and is regulated differentially in these two subcellular compartments. In the brain, 3β-HSD is present, but its subcellular compartmentalization is unknown. Here, in Study 1, we examined the subcellular localization of 3β-HSD in the brain of a songbird, the zebra finch. In Study 2, in males and females, we determined whether 3β-HSD activity in different subcellular compartments is rapidly regulated by in vitro treatment with estradiol (E(2) ), which has many rapid effects on the brain. Brain 3β-HSD was enriched primarily in microsomes and secondarily in mitochondria and synaptosomes. In both males and females, E(2) treatment rapidly (within 5 min) inhibited 3β-HSD activity in both mitochondria/synaptosomes and microsomes, with greater inhibition in microsomes. We also assessed the activity of 5β-reductase, which acts on androstenedione. E(2) rapidly inhibited 5β-reductase activity in microsomes only. This is the first study to examine the subcellular localization of 3β-HSD in the brain, and the data demonstrate the importance of subcellular localization for the regulation of steroidogenic enzymes in the brain.
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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) | 0.000 | 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) | 0.001 | 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 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".