Brain serotonin synthesis and Na+,K+-ATPase activity are increased postnatally after prenatal administration of L-tryptophan.

The effect of prenatal L-tryptophan supplementation on the serotonin (5-HT) synthesis and the activity of Na+,K+-ATPase in the cerebral cortex was studied during postnatal development, from birth up to day 30. A parallel and significant elevation of the serotonin content and the activity of tryptophan-5-hydroxylase was observed in the brain of infant rats born to mothers treated with L-tryptophan, as related to non-treated controls. The activity of Na+,K+-ATPase was also significantly elevated at the different ages studied throughout the developmental period, as related to controls. These results suggest an important role of L-tryptophan in the early regulation of the serotonin-synthesizing machinery, which lasts postnatally. Elevation of ATPase activity seems to be associated to the elevation in the activity of the 5-HT system.