Expression of c-fos Protein in Rat Brain Elicited by Electrical and Chemical Stimulation of the Hypothalamic Paraventricular Nucleus
Bibliographic record
Abstract
The functional connectivity of the paraventricular nucleus of the hypothalamus (PVN) was studied by assessing the expression of the immediate early gene, c-fos, after unilateral stimulation of this structure in urethane-anesthetized rats. Electrical stimulation for 1 h (10 s on, 10 s off; 15-40 microA at 20 Hz) was accompanied by increases in mean arterial pressure (13-29 mm Hg). In these animals, ipsilateral increases in numbers of neurons with Fos-like immunoreactivity (FLI) were immunohistochemically demonstrated in the insular cortex, lateral septum, medial amygdala, hypothalamus, lateral division of the parabrachial nucleus (PBN) of the pons and the nucleus of the tractus solitarius (NTS) and ventrolateral medulla (VLM). Numbers of cells with FLI were quantitated in five areas known for their roles in autonomic function: arcuate nucleus, ventromedial hypothalamus, lateral PBN, NTS (at three levels) and VLM (caudal and rostral). In each case, stimulation of the PVN led to significant differences in number of neurons with FLI on the side ipsilateral to the stimulation compared to the contralateral side. To eliminate effects associated with stimulation of fibers of passage in the vicinity of the PVN, the results after electrical stimulation were compared to those obtained in animals in which the PVN was chemically stimulated unilaterally with the excitatory amino acid L-glutamate (5 one-minute infusions of 50 nl, 0.5 M glutamate over 1 h). Mean arterial pressure was increased after each injection (7-13 mm Hg), and significant differences in numbers of neurons with FLI between sides were maintained in all five areas except the NTS caudal to, and at, the level of the area postrema. An increase in neurons with FLI in the piriform cortex of all animals including controls may be due to injury-induced activation of target neurons from the PVN. These data illustrate that electrical and chemical stimulation of the PVN leads to simultaneous activation of neurons in many targets. All of the target areas studied receive direct projections from the PVN, although multisynaptic projections may also contribute to activation of target neurons.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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".