1 administration to rats of a 0.5 mg/kg dose of any of 19 antidepressants , but not that of many other drugs , causes a significant inhibition of the total enzyme and apoenzyme activities of liver tryptophan pyrrolase ( of 24-48 % and 37-65 % respectively ) and elevates brain tryptophan concentration by 13-66 % .
C0006104
brain
C0086045
concentration