Do Birth Variable Data Predict Melatonin Production in 8- to 9-Year-Old Children? Analysis of Excreted 6-Sulfatoxymelatonin

Associations of urinary 6-sulfatoxymelatonin with demographics, body mass, sex steroids, and lifestyle factors in preschool Japanese children

PURPOSE

We aimed to assess the associations of sex, age, body mass, sex steroid hormones, and lifestyle factors with the levels of melatonin in young children.

METHODS

This study followed a cross-sectional design and was conducted two preschools in Japan. Subjects were 235 boys and 203 girls, aged 3-6 years. Information related to demographics, body mass, and lifestyle factors was obtained from parent-administered questionnaires. The levels of 6-sulfatoxymelatonin and dehydroepiandrosterone in first-void morning urine were measured by radioimmunoassay. Urinary estrone, estradiol, testosterone, and 5-androstene-3β, 17α diol levels were measured by liquid chromatography-electrospray ionization tandem mass spectrometry.

RESULTS

The creatinine-corrected 6-sulfatoxymelatonin levels and the estimated value of 6-sulfatoxymelatonin excretion were higher in girls than in boys. After adjustments for age, the creatinine-corrected 6-sulfatoxymelatonin was negatively associated with weight and body mass index among boys and with weight and height among girls. However, the estimated value of 6-sulfatoxymelatonin excretion was not associated with any indices of body mass. No significant relationships of urinary sex steroids, light exposure at night, sleep time, sedentary lifestyles, or passive smoking with urinary 6-sulfatoxymelatonin were observed.

CONCLUSIONS

Our findings suggest that melatonin levels depend on sex and body size among young healthy children. Our results should be confirmed in future researches.

Potential utility of melatonin as an antioxidant during pregnancy and in the perinatal period

Reactive oxygen species (ROS) play a critical role in the pathogenesis of various diseases during pregnancy and the perinatal period. Newborns are more prone to oxidative stress than individuals later in life. During pregnancy, increased oxygen demand augments the rate of production of ROS and women, even during normal pregnancies, experience elevated oxidative stress compared with non-pregnant women. ROS generation is also increased in the placenta during preeclampsia. Melatonin is a highly effective direct free-radical scavenger, indirect antioxidant, and cytoprotective agent in human pregnancy and it appears to be essential for successful pregnancy. This suggests a role for melatonin in human reproduction and in neonatal pathologies (asphyxia, respiratory distress syndrome, sepsis, etc.). This review summarizes current knowledge concerning the role for melatonin in human pregnancy and in the newborn. Numerous studies agree that short-term melatonin therapy is highly effective in reducing complications during pregnancy and in the neonatal period. No significant toxicity or treatment-related side effects with long-term melatonin therapy in children and adults have been reported. Treatment with melatonin might result in a wide range of health benefits, including improved quality of life and reduced healthcare costs.

Melatonin levels during the first week of life and their relation with the antioxidant response in the perinatal period

AIM

Melatonin is a potent free radical scavenger and an indirect antioxidant. Knowledge about the behavior of melatonin secretion in the early neonatal period, which may relate to its properties at a vital stage during very high antioxidant demands, is limited.

PATIENTS AND METHODS

We studied 35 newborns admitted to the Neonatal Unit with respiratory distress syndrome (RDS) and with no signs of sepsis, severe anemia, hemodynamic compromise or malformation. The gestational age of the newborns was 26-40 weeks (mean value 32.5 weeks) and the weight at birth was 870-4,400 g (mean value 1,800 g). They were classified into two groups: <or=1,500 g or >1,500 g birthweight. In all cases, at 09:00 h on their 1st, 3rd and 7th days of life, serum melatonin was measured by RIA. The clinical history was recorded and treatment and follow-up were performed according to established neonatology practice, and the resultant data recorded. Informed consent from the parents or guardians was obtained in accordance with the Declaration of Helsinki. Statistical analysis was carried out using ANOVA-II (factor I: day of sample; factor II: birthweight).

RESULTS

There were significant increases in melatonin levels with increasing birthweight (p = 0.017), but no changes by day of sample. Although in both study groups melatonin levels increased during the first few days this was not statistically significant.

CONCLUSIONS

In newborns of low birthweight, we report high melatonin concentrations in the morning and during the first week of life. These increase with maturation, and at full-term were similar to nocturnal levels during the acrophase of pineal gland secretion in toddlers and schoolage children, when pineal gland secretion is maximal and takes place reflecting environmental variations. In the early neonatal period these high levels of melatonin seem to derive from extrapineal sources, which mature to provide antioxidant protection in accordance with other elements of the antioxidant network to compensate for the high levels of oxidative stress that are present in the perinatal period.