Mother's melatonin reduces stress hormone production in the primate fetal adrenal gland

Newborns from mothers exposed to constant light had twice as much plasma cortisol as those from mothers under a normal light-dark schedule.

• A melatonin receptor was found in 90% of gestation capuchin monkey fetal adrenals, indicating maternal influence on adrenal function.
• Melatonin inhibited cortisol production stimulated by certain hormones in vitro, suggesting a regulatory role in adrenal activity.
• Chronic suppression of maternal melatonin through constant light did not affect maternal oestradiol levels.
• Increased plasma cortisol in newborns was linked to maternal melatonin suppression, highlighting its potential role in cortisol regulation.
• Daily melatonin replacement for mothers under constant light normalized plasma cortisol levels in newborns.

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