single doses of dl-alpha-amino-beta- ( 2-pyridine ) propanoic acid ( 2-pa , 100 mg/kg ) significantly decreased the holoenzyme and apoenzyme activities of rat liver tryptophan pyrrolase ( tp ) and increased brain tryptophan , serotonin ( 5-ht ) and 5-hydroxyindole-3-ylacetic acid concentrations .
C0006104
brain
C0086045
concentrations