Increased Colocalization of Corticotropin-Releasing Factor and Arginine Vasopressin in Paraventricular Neurones of the Hypothalamus in Lactating Rats: Evidence from Immunotargeted Lesions and Immunohistochemistry
Bibliographic record
Abstract
In lactating female rats, tonically elevated glucocorticoid secretion is accompanied by blunted stress responsiveness, reduced expression of hypothalamic corticotropin-releasing factor (CRF) mRNA and modest increases in arginine vasopressin (AVP) expression in the paraventricular nucleus (PVN). To determine the relative contribution of CRF and AVP to parvocellular function, we performed selective CRF (CRF-Tx) or AVP (AVP-Tx) lesions in the PVN neurones of ovariectomized virgin or lactating females (day 2 of lactation) by using ricin A associated with monoclonal antibodies directed towards CRF or AVP. We also performed double immunohistochemical labelling of CRF and AVP in the PVN of control rats injected with immunoglobulin (Ig)Gs associated with the ricin A (IgG-Tx). Brains were collected 12 days after the lesion and processed for in situ hybridization of CRF and AVP mRNA or for double fluorescence CRF and AVP immunohistochemistry. We found that lactating females exhibit a high degree of CRF and AVP colocalization in parvocellular PVN neurones, hypothalamic processes and median eminence terminals compared to virgins. While CRF mRNA is significantly reduced in lactating rats, AVP mRNA and protein levels are greatly enhanced in parvocellular PVN neurones during lactation. Hypothalamic CRF or AVP ricin-A lesions significantly reduced both CRF and AVP expression (15-35% decrease) as well as peptide immunoreactivity in PVN neurones in both groups of females. The specificity of the lesions varied between virgins and lactators since in virgin females, AVP-Tx did not affect CRF mRNA expression whereas in lactating females, this same lesion significantly reduced CRF mRNA expression, suggesting that parvocellular PVN neurones are more sensitive to the effects of the lesions during lactation. In both virgins and lactators, lesion with CRF-Tx tended to increase AVP mRNA expression; however, in virgins, parvocellular PVN neurones were possibly compensating for the loss of CRF synthesis by increasing AVP expression and immunoreactivity. We conclude that lactation is associated with a high degree of CRF and AVP colocalization in parvoPVN neurones and that the increased AVP production in these neurones increases their sensitivity to immunotargeted lesions. The opposite regulation of CRF and AVP gene expression during lactation might provide a useful model to study differential sensitivity to glucocorticoid feedback or hypothalamic activation of transcription factors.
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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".