Bibliographic record
Abstract
Neurogenesis occurs in adulthood, but is limited to the subventricular zone (SVZ) giving rise to olfactory neurons (1–3). In a recent paper in Science (299:117–120, 2003) Shingo et al. from Calgary, Alberta, Canada hypothesized that maternal need for heightened olfaction in rearing offspring results in pregnancy-induced neurogenesis. Cells in the SVZ of pregnant and nonpregnant mice were labeled to quantify neurogenesis and determine the fate of SVZ neural stem cells (NSC). Following bromodeoxyuridine (BrdU) injection, the number of BrdU+ cells increased by 65% and the Ki67(MIB) index by 100% in gestational-day-7 mice compared to virgin mice (Figure). BrdU+ cells also migrated to the olfactory bulb. Next, pregnancy-induced SVZ neurogenesis was examined. A “pseudopregnancy” state, achieved by mating virgin females with vasectomized males, produced a transient alteration in maternal hormones. Interestingly, these pseudopregnant mice showed an increase (42%) in NSC proliferation, demonstrating that embryo implantation is not necessary for neurogenesis.Figure: Fluoresence micrographs of the forebrain SVZ show an increase in the numbers of BrdU-labeled cells at GD7, compared with that in virgin females(Science 299:117–120, 2003).What induces SVZ neurogenesis? The failure of estrogen and/or progesterone to induce proliferation implicated prolactin, especially as its receptors are increased adjacent to the SVZ (5–6). Prolactin infusion into ovariectomized, nonpregnant females, resulted in a 53–61% increase in BrdU+ cells. A parallel doubling of olfactory neurons confirmed prolactin's role in SVZ neurogenesis. Prolactin-induced neurogenesis was also seen in males, but, to a lesser degree. These results are fascinating, especially considering the changing notion that the adult brain is not static, but rather that neurogenesis, remodeling, and plasticity persist in the adult CNS. Once the fate of neural stem cells can be directed to specific CNS targets, the clinical potential of prolactin-induced neurogenesis is limitless. Until then, this study demonstrates a promising experimental model to study adult CNS neurogenesis. DEEPA SONI, M.D. ROBERT M. FRIEDLANDER, M.D. BASIC SCIENCES RESEARCH
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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 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.014 | 0.004 |
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".