Dopamine-Induced Physical Barrier to Inhibit Prolactin Release in Mammotrophs Disappears during Resumption of Prolactin Secretion
Bibliographic record
Abstract
After finding that dopamine can cause extensive changes in mammotroph ultrastructure within 2 min of administration, we further examined mammotrophs 20 and 40 min after dopamine injection when prolactin secretion had resumed. Dopamine (1,000 micrograms/kg) was injected into the right atrium of estradiol-primed male rats through indwelling cannulae. Rats were killed by decapitation 2, 20 and 40 min after dopamine treatment and their pituitaries were processed for electron microscopy. Within 2 min of administration, dopamine completely stopped prolactin release and significant changes in mammotroph ultrastructure were observed: peripheral relocation of rough endoplasmic reticulum (RER) ('dopamine barrier'); fewer secretory granules in close proximity to the cell membrane; fewer exocytoses, and increased numbers of 'intracellular bodies' associated with secretory granules (putative granule disposal system). 20 min following dopamine administration, when prolactin secretion had resumed, there appeared to be a breaking up of the 'RER barrier' in that more vesicular elements were seen and the amount of peripheral RER was reduced; more granules were adjacent to the cell membrane and exocytotic figures were more numerous. 'Intracellular bodies' decreased in number. By 40 min, mammotrophs appeared to resemble those of estradiol-primed controls with the RER stacked to one side of the cell and small numbers of 'intracellular bodies'. The correlation between ultrastructural changes in mammotrophs and prolactin release implies that the 'RER barrier' is part of a mechanism by which prolactin release is inhibited.
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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 | 0.000 |
| 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) | 0.000 | 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".