Expression of melatoninergic receptors in human placental choriocarcinoma cell lines.
BACKGROUND
Melatonin crosses the placenta and enters the fetal circulation. Moreover, experimental data suggest a possible influence of melatonin on placental function and fetal development in humans. To date, the expression and role of melatonin receptors in human placenta choriocarcinoma cell lines and in human term placental tissues remain to be elucidated.


RESULTS
Results from RT-PCR, western blotting and confocal microscopy demonstrated that the MT1, MT2 and RORalpha1 melatonin receptors are expressed in the human term placental tissues and in choriocarcinoma cell lines JEG-3 and BeWo. Furthermore, enzyme-linked immunosorbent assay showed that 6-chloromelatonin (a melatonin agonist) inhibits, in a dose-dependent manner, forskolin-stimulated hCG-beta secretion in JEG-3 (P < 0.001) and BeWo (P < 0.05) cells but had no effect on basal human chorionic gonadotrophin (hCG-beta) levels. This effect of 6-chloromelatonin on forskolin-stimulated HCG-beta secretion was abolished by pertussis toxin (PTX), suggesting that melatonin regulates hCG-beta production by an action involving an inhibitory Gi/o protein. In PTX-treated BeWo cells, 6-chloromelatonin stimulated basal hCG-beta secretion (P < 0.001).


CONCLUSIONS
These results demonstrate, for the first time, the expression of melatonin receptors in human term placental tissues and in choriocarcinoma cells and suggest a possible paracrine/autocrine function for melatonin in human placenta.
Lanoix
Dave
D
Department of Chemistry and Biochemistry, Université de Moncton, Moncton, New Brunswick, Canada.
Ouellette
Rodney
R
Vaillancourt
Cathy
C
D045744:Cell Line, Tumor; D002822:Choriocarcinoma / Q000378:metabolism*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000378:metabolism*; D005260:Female; D005455:Fluorescent Antibody Technique; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D008550:Melatonin / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; D037342:Pertussis Toxin / Q000494:pharmacology; D010920:Placenta / Q000378:metabolism*; D044122:Receptor, Melatonin, MT1 / Q000096:biosynthesis; D044123:Receptor, Melatonin, MT2 / Q000096:biosynthesis; D018160:Receptors, Cytoplasmic and Nuclear; D044094:Receptors, Melatonin / Q000096:biosynthesis*; D018168:Receptors, Retinoic Acid / Q000096:biosynthesis*; D015534:Trans-Activators
D018997:Chorionic Gonadotropin, beta Subunit, Human; D057094:Nuclear Receptor Subfamily 1, Group F, Member 1; D044122:Receptor, Melatonin, MT1; D044123:Receptor, Melatonin, MT2; D018160:Receptors, Cytoplasmic and Nuclear; D044094:Receptors, Melatonin; D018168:Receptors, Retinoic Acid; D015534:Trans-Activators; C024100:6-chloromelatonin; D037342:Pertussis Toxin; D008550:Melatonin