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Free tryptophan as an indicator of brain serotonin synthesis in infants
G Manjarrez1, J L Contreras, G Chagoya
1Centro Médico Nacional, Departamento de Fisiología, Biofísica y Neurociencias, Facultad de Medicina, U.A.Q., Qro. Mexico City, Mexico.
Insights
Infants with early life malnutrition show elevated free L-tryptophan levels, potentially increasing brain serotonin synthesis. This may impact neurogenesis and brain development long-term.
Area of Science:
- Neonatal nutrition
- Neuroscience
- Biochemistry
Background:
- Intrauterine malnutrition affects newborn development.
- Serotonin plays a role in fetal brain neurotrophic functions.
- Previous studies indicated altered L-tryptophan and serotonin in malnourished rat brains.
Purpose of the Study:
- To confirm and extend previous findings on plasma L-tryptophan in malnourished infants.
- To investigate the link between free L-tryptophan and brain serotonin synthesis in early life.
- To explore the potential of plasma L-tryptophan as a marker for altered brain serotonin metabolism.
Main Methods:
- Analysis of plasma samples from preterm and term newborn infants with intrauterine malnutrition.
- Observation extended through the lactational period up to 3 months of age.
Main Results:
- Significantly elevated free fraction of L-tryptophan observed up to 3 months of age.
- Suggests increased precursor availability for brain serotonin synthesis.
- Data supports the hypothesis of activated brain serotonin synthesis in early-life malnourished humans.
Conclusions:
- Elevated free L-tryptophan in plasma may indicate increased brain serotonin synthesis in infants with early life malnutrition.
- Altered serotonin metabolism during this critical period could impact neurogenesis.
- Further research is needed to confirm the functional relevance of the brain serotonergic system in these patients.
Abstract:
This study confirms observations made in a former study of plasma of preterm and term newborn infants with intrauterine malnutrition during the first month of life and extends to the lactational period. The free fraction of L-tryptophan, the precursor amino acid of brain serotonin synthesis, is significantly elevated up to 3 months of age. According to previous results, which demonstrated that L-tryptophan and serotonin synthesis are increased in the brain of gestationally malnourished rats, the present data in humans malnourished early in life strongly suggest that the elevation of the free fraction of L-tryptophan in plasma provides an increased amount of the precursor molecule to pass across the blood-brain barrier and activates the synthesis of brain serotonin. Because serotonin has been found to have a possible neurotrophic role in the fetal brain, any alteration of its metabolism in this period could reflect as a permanent change in brain neurogenesis. The data suggest that the free fraction of plasma L-tryptophan may be an indirect marker of changes in brain serotonin synthesis in these patients. Additional data on the functional relevance of the brain serotonergic system in humans are required to support this hypothesis.