The Expression of Voltage‐Gated Ca<sup>2+</sup> Channels in Pituicytes and the Up‐Regulation of L‐Type Ca<sup>2+</sup> Channels During Water Deprivation
Bibliographic record
Abstract
The primary components of the neurohypophysis are the neuroendocrine terminals that release vasopressin and oxytocin, and pituicytes, which are astrocytes that normally surround and envelop these terminals. Pituicytes regulate neurohormone release by secreting the inhibitory modulator taurine in an osmotically-regulated fashion and undergo a marked structural reorganisation in response to dehydration as well as during lactation and parturition. Because of these unique functions, and the possibility that Ca2+ influx could regulate their activity, we tested for the expression of voltage-gated Ca2+ channel alpha1 subunits in pituicytes both in situ and in primary culture. Colocalisation studies in neurohypophysial slices show that pituicytes (identified by their expression of the glial marker S100beta), are immunoreactive for antibodies directed against Ca2+ channel alpha1 subunits Ca(V)2.2 and Ca(V)2.3, which mediate N- and R-type Ca2+ currents, respectively. Pituicytes in primary culture express immunoreactivity for Ca(V)1.2, Ca(V)2.1, Ca(V)2.2, Ca(V)2.3 and Ca(V)3.1 (which mediate L-, P/Q-, N-, R- and T-type currents, respectively) and immunoblotting studies confirmed the expression of these Ca2+ channel alpha1 subunits. This increase in Ca2+ channel expression may occur only in pituicytes in culture, or may reflect an inherent capability of pituicytes to initiate the expression of multiple types of Ca2+ channels when stimulated to do so. We therefore performed immunohistochemistry studies on pituitaries obtained from rats that had been deprived of water for 24 h. Pituicytes in these preparations showed a significantly increased immunoreactivity to Ca(V)1.2, suggesting that expression of these channels is up-regulated during the adaptation to long-lasting dehydration. Our results suggest that Ca2+ channels may play important roles in pituicyte function, including a contribution to the adaptation that occurs in pituicytes when the need for hormone release is elevated.
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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) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 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 | 0.001 |
| 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".