Prenatal impairment of brain serotonergic transmission in infants.

OBJECTIVE

To evaluate whether the free fraction of L-tryptophan (L-Trp) and the N1/P2 component of the auditory evoked potentials (AEPs) are associated with impaired brain serotonin neurotransmission in infants with intrauterine growth restriction (IUGR).

STUDY DESIGN

We measured free, bound, and total plasma L-Trp and recorded the N1/P2 component of AEP in a prospective, longitudinal, and comparative study comparing IUGR and control infants.

RESULTS

Plasma free L-Trp was increased and the amplitude of N1/P2 component was significantly decreased in IUGR relative to control infants. The free fraction of L-Trp and N1/P2 component had a negative association.

CONCLUSIONS

In newborns with IUGR, the changes in measured plasma free fraction of L-Trp and in the amplitude the N1/P2 component of the AEP suggest an inverse association between free L-Trp and components of the AEP. The changes observed in the free fraction of L-Trp and AEP may be causally associated with brain serotonergic activity in utero. In IUGR, epigenetic factors such as stress-induced disturbances in brain serotonin metabolism or serotonergic activity, identifiable by alterations in AEP, influence cerebral sensory cortex development and may be causally associated with serotonin-related disorders in adulthood.