Effects of Daily Afternoon Melatonin Administration on Monoamine Accumulation in Median Eminence and Striatum of Ovariectomized Hamsters Receiving Pargyline
Bibliographic record
Abstract
The effects of daily afternoon melatonin injections on the accumulation of monoamines were studied in extracts of median eminence, and of caudate nucleus, of intact and ovariectomized Syrian hamsters which were administered pargyline 2 h prior to sacrifice. Although no significant effect of melatonin administration on the serotonin (5HT) accumulation after pargyline could be detected, significantly increased amounts of 5HT and of the 5HT metabolite, 5-hydroxyindole acetic acid, were detected in median eminence and in caudate nucleus of melatonin-injected hamsters not treated with pargyline. In both median eminence and in posterior pituitary, dopamine (DA) concentrations were significantly reduced by melatonin administration. In the median eminence of intact hamsters, the accumulation of DA after pargyline was reduced to 22% of controls by melatonin injections; in ovariectomized hamsters, the accumulation of DA was reduced to 9% of controls by melatonin injections. The accumulation of norepinephrine after pargyline was significantly reduced by melatonin administration only in ovariectomized hamsters. No significant inhibitory effects of melatonin injections could be detected on DA accumulation in caudate nucleus. These data suggest that melatonin injections result in substantial inhibition of daytime DA synthesis in median eminence independently of its effects on gonadal steroids. Paradoxically, melatonin-induced inhibition of median eminence DA activity occurred concomitantly with suppression of pituitary and plasma prolactin (PRL). We conclude that daily afternoon melatonin injections inhibit PRL secretion and interfere with cycles of LH in spite of decreased DA activity in the median eminence.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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".