Specific Na<sup>+</sup>Sensors Are Functionally Expressed in a Neuronal Population of the Median Preoptic Nucleus of the Rat
Bibliographic record
Abstract
Whole-cell patch-clamp recordings were performed on acute brain slices of male rats to investigate the ability of the neurons of the median preoptic nucleus (MnPO) to detect fluctuation in extracellular osmolarity and sodium concentration ([Na+]out). Local application of hypotonic and hypertonic artificial CSF hyperpolarized and depolarized the neurons, respectively. Similar responses obtained under synaptic isolation (0.5 microM TTX) highlighted the intrinsic ability of the MnPO neurons to detect changes in extracellular osmolarity and [Na+]out. Manipulating extracellular osmolarity, [Na+]out, and [Cl-]out showed in an independent manner that the MnPO neurons responded to a change in [Na+]out exclusively. The specific Na+ response was voltage insensitive and depended on the driving force for Na+ ions, indicating that a sustained background Na+ permeability controlled the membrane potential of the MnPO neurons. This specific response was not reduced by Gd3+, amiloride, or benzamil, ruling out the participation of mechanosensitive cationic channels, specific epithelial Na+ channels, and Phe-Met-Arg-Phe-gated Na+ channels, respectively. Combination of in situ hybridization, using a riboprobe directed against the atypical Na+ channel (Na(X)), and immunohistochemistry, using an antibody against neuron-specific nuclei protein, revealed that a substantial population of MnPO neurons expressed the Na(X) channel, which was characterized recently as a concentration-sensitive Na+ channel. This study shows that a neuronal population of the MnPO acts as functional Na+ sensors and that the Na(X) channel might represent the molecular basis for the extracellular sodium level sensing in these 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 | 0.000 |
| 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 | 0.001 | 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".