measurements have been taken of the serotonin and its metabolites ( tryptophan , 5-hydroxytryptophan , 5-hydroxy-3-indolacetic acid and 5-hydroxytryptophol ) in each structure of the geniculate and extrageniculate visual system of rats aged between 3 and 30 months .
C0041249
tryptophan
C0000578
5-hydroxytryptophan