MELATONIN TOGETHER WITH NORADRENALINE AUGMENTS CONTRACTIONS OF HUMAN MYOMETRIUM

The hormone melatonin is known to influence the circadian rhythm, and it probably also mediates some of the physiological changes that occur in the body at night. Inasmuch as uterine activity is greater during darkness, we investigated whether melatonin could modulate uterine con tractility. Biopsies were performed during caesarean sections to obtai n uterine tissue from women who had reached full term. The obtained sa mples were mounted in organ baths, and spontaneous contractions were r ecorded. Melatonin alone did not change myometrial contractility, wher eas melatonin in combination with noradrenaline potentiated contractio ns. These results may indicate that melatonin plays a role in the timi ng of labour, since labour often begins late in the evening.