Effect of Dietary Phenylalanine and Tryptophan on Pineal and Hypothalamic Serotonin Levels.

Abstract

Summary Long-Evans rats were placed on diets containing 5% L-tryptophan or 7% L-phenylalanine or without supplements, when 4 weeks old and were sacrificed 5, 9, 12, or 19 days later. The high tryptophan diet led to a 250% increase in pineal and a nearly 100% increase in hypothalamic serotonin within 5 to 9 days. The high phenylalanine diet led to a 30% reduction in serotonin content in both tissues. These results are compared with those from whole brain.