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Plasma and urinary melatonin in male infants during the first 12 months of life
Insights
In male infants, plasma melatonin levels are low during early high testosterone and luteinizing hormone activity, then rise as testicular function declines. Urinary melatonin excretion remains stable, indicating altered synthesis or use.
Area of Science:
- Endocrinology
- Pediatric endocrinology
- Chronobiology
Background:
- Neonatal endocrine profiles are dynamic.
- Hormonal changes in early infancy influence development.
- Melatonin's role in infant physiology requires further elucidation.
Purpose of the Study:
- To investigate the relationship between melatonin and key reproductive hormones in male infants.
- To examine the temporal dynamics of melatonin and hormones during the first year of life.
Main Methods:
- Radioimmunological assays were used to measure plasma and urinary melatonin, testosterone, and luteinizing hormone.
- 26 male infants were studied longitudinally during their first year of life.
Main Results:
- Plasma melatonin levels were inversely correlated with postnatal elevations in testosterone and luteinizing hormone.
- Melatonin levels increased as testicular activity decreased in the first year.
- Urinary melatonin excretion showed no significant variation throughout the study period.
Conclusions:
- Infant endocrine rhythms show complex interplay between melatonin and reproductive hormones.
- Stable urinary melatonin excretion suggests regulatory changes in melatonin synthesis or metabolism, not just excretion.
- Further research is needed to understand melatonin's specific role in infant development and its regulation.
Abstract:
Plasma and urinary melatonin, testosterone and luteinizing hormones were radioimmunologically assayed in 26 male babies during the first year of life. The results show that plasma melatonin levels are low during the phase of postnatal elevation of testosterone and luteinizing hormones. They subsequently increase when testicular activity decreases. Urinary elimination of melatonin does not vary during this period, suggesting the existence of variations in the synthesis or utilization of melatonin.