night-time pineal levels of tryptophan , 5-hydroxytryptophan , serotonin , n-acetylserotonin , melatonin , 5-hydroxyindoleacetic acid and the activities of the two enzymes n-acetyltransferase and hydroxyindole-o-methyltransferase involved in the cyclic production of melatonin were determined in male albino rats and syrian hamsters that were implanted with thyroxine or thyroidectomized two weeks earlier .
C0041249
tryptophan
C0000578
5-hydroxytryptophan