Vasopressin Acts in the Subfornical Organ to Decrease Blood Pressure
Bibliographic record
Abstract
In addition to its traditional role as a circulating vasoactive peptide, vasopressin (VP) has been shown to play significant roles in central cardiovascular processing. The recent description of VP receptors within the subfornical organ (SFO) has suggested this circumventricular organ (CVO) as a potential locus for feedback actions of circulating VP on the brain. The well-established anatomical connections between SFO and hypothalamic autonomic control centers provide further arguments in support of such a view. This study was undertaken to determine the physiological consequences of activation of VP receptors within the SFO of urethane anesthetized rats. Microinjection (0.5 microliter) of 5 pmol VP into SFO resulted in significant decreases in blood pressure (BP, mean AUC -638.3 +/- 110.3 mm Hg.s, p < 0.01, n = 13) without a change in heart rate (HR, mean AUC 7.9 +/- 14.0 beats, p > 0.05, n = 12), effects which were repeatable. These depressor effects were specific to microinjection locations within this CVO as similar VP microinjections into non-SFO tissue were without effect on BP (mean AUC 245.4 +/- 111.5 mm Hg.s, p > 0.05, n = 10), or HR (mean AUC 1.8 +/- 3.1 beats, p > 0.05, n = 9). In contrast to the former depressor effects, VP microinjection (5 pmol in 0.5 microliter) into the third ventricle produced large increases in BP (mean AUC 1,461.8 +/- 368.97 mm Hg.s, p < 0.05, n = 6) again with no change in HR (mean AUC 1.4 +/- 5.96 beats, p > 0.05, n = 6). The hypotensive effects observed in response to VP microinjection into SFO were abolished by systemic treatment with a V1 receptor antagonist (mean AUC 89.5 +/- 67.7 mm Hg.s, p > 0.05) compared to BP response before V1 receptor blockade (mean AUC -605.9 +/- 119.8 mm Hg.s, n = 4). These results suggest that the SFO may be an essential structure in the feedback control loop through which circulating VP influences descending autonomic pathways involved in cardiovascular control.
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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".