Postnatal Development of Pineal Synthesis and Secretion of Melatonin

It is still unclear why the pineal gland is not able to start its own pulsatile synthesis and secretion of melatonin in the first months of a human's life, so that infants during this time are dependent on the external supply of melatonin via breast milk, unpooled donor milk from breast milk collection centres or industrially produced chrononutrition with melatonin-poor day milk and melatonin-rich night milk. According to current knowledge, the pineal gland and melatonin receptors are already present at birth, the suprachiasmatic nucleus is largely functional and noradrenaline, the key pineal transmitter, can be detected in the early foetal period. However, the development and differentiation of the pineal gland, the pinealocytes as the site of melatonin synthesis and the associated Lhx4 homebox only occurs during the first year of a person's life. The resulting "physiological" melatonin deficiency is associated with sleep disorders, infant colic and increased crying in babies. Intervention studies indicate that this deficiency should be compensated for – through breastfeeding, the administration of unpooled donor milk or through industrially produced chrononutrition made from unpooled cow's milk with melatonin-poor day milk and melatonin-rich night milk [1-3], see also Video [4].