Histidine decarboxylase deficiency in gene knockout mice elevates male sex steroid production
Bibliographic record
Abstract
Histamine is synthesized in cells by histidine decarboxylase (HDC). HDC-deficient knockout (KO) mice lack functional HDC and histamine in the tissues. In the present study we used this in vivo model for studying the role of HDC deficiency in the regulation of male steroid hormone metabolism. In agreement with earlier studies showing the lack of effects of central histamine on the basal secretion of gonadotrope hormones, we found no difference with in situ hybridization in the expression of GnRH in the hypothalamus of wild type and KO mice. The tissue concentrations of testosterone and several androgenic steroids were significantly elevated in the testes but not in the adrenal glands of HDC-KO mice. In contrast, serum estradiol levels failed to show a significant difference between the two groups. The weight of the testes was significantly smaller in both 7-day-old and adult KO mice. The ultrastructure of the adult testis indicated elevated steroid synthesis with more tightly coiled membranous whorls in Leydig cells. The present results suggest that changes in reproductive functions and sex steroid secretion in male HDC-KO mice are not due to altered hypothalamic GnRH expression but are probably related to definite modifications during fetal development of KO mice reinforced later by the lack of the effect of peripheral histamine. This may provide in vivo evidence that peripheral histamine is an important regulatory factor of male gonadal development during embryogenesis and of sex steroid metabolism later in adulthood.
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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) | 0.002 | 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".