Human placental trophoblasts synthesize melatonin and express its receptors
Bibliographic record
Abstract
Although the role of melatonin on fetal development has been the subject of a number of studies, little is known about the function of melatonin in the placenta. We previously showed that melatonin receptors are expressed and are functional in JEG-3 and BeWo cell lines, both in vitro models of human trophoblast. Local synthesis of melatonin in placenta has been proposed, but the human placenta's ability to synthesize melatonin de novo has never been studied. The purpose of this study was to investigate the expression [reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis] and activity (radiometric assay) of melatonin synthesizing enzymes, and characterize the expression of the melatoninergic receptors in human term villous trophoblast. The results show that arylalkylamine N-acetyltransferase and hydroxyindole O-methyltransferase melatonin synthesizing enzymes are expressed and active in villous trophoblast as well as in JEG-3 and BeWo placental choriocarcinoma cells. In addition, immunohistochemical analysis demonstrated the presence of MT1, MT2, and retinoid-related orphan nuclear receptor alpha melatonin receptor proteins in both villous cytotrophoblast and syncytiotrophoblast (STB) as well as in endothelial cells surrounding the fetal capillaries and in the villous mesenchymal core. RT-PCR and western blot analysis in primary cultures of human term trophoblast confirmed the expression of all three melatonin receptors in villous cytotrophoblast and STB cells. This study demonstrates for the first time a local synthesis of melatonin and expression of its receptors in human trophoblasts and strongly suggests a paracrine, autocrine, and/or intracrine role for this indolamine in placental function and development as well as in protection from oxidative stress.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.000 |
| 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) | 0.002 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".