Systemic Angiotensin Acts at the Subfornical Organ to Control the Activity of Paraventricular Nucleus Neurons with Identified Projections to the Median Eminence
Bibliographic record
Abstract
The present studies were carried out to investigate the mechanisms through which systemic angiotensin II (AII) acts within the central nervous system to influence the release of anterior pituitary hormones in the Sprague-Dawley rat. In particular, these studies have examined the role of the subfornical organ (SFO) as an essential structure mediating these responses. Extracellular single-unit recordings were obtained from 199 paraventricular nucleus (PVN) neurons anti-dromically identified as projecting to the median eminence. Different groups of these neurons were tested for the effects of either electrical stimulation in the SFO (n = 87) or systemic AII administration in intact (n = 49) and SFO-lesioned (n = 25) animals. Of cells tested with SFO stimulation 45% were excited, 16% inhibited, and the remainder unaffected. Neurons which were excited were primarily located just medial to the magnocellular neurons in the region where the majority of corticotropin-releasing hormone immunoreactive cells are found. In contrast, inhibitory responses were observed in cells located in the dorsal medial PVN, a region containing thyrotropin-releasing hormone, somatostatin, and dopamine PVN-median eminence neurons. Following systemic AII 42% of cells tested showed increased activity specific to the effects of this peptide, and 20% showed alterations in activity associated with the cardiovascular changes induced by AII. In contrast, following SFO lesion only 8% of neurons tested showed specific excitatory responses to AII. In order to test the hypothesis that systemic AII may activate this excitatory SFO to PVN pathway, a further group of 35 neurons were tested with both SFO stimulation and AII. Excitatory responses to AII were observed in 13 of these cells, each of which was also excited by SFO stimulation. These studies describe mechanisms through which the central nervous system may sense peripheral concentrations of peptide hormones and modulate the activity of neural pathways which in turn influence the activity of PVN neurons which control the secretion of anterior pituitary hormones.
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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".