“…In favor of this proposal are the findings of Park et al (1965), that both MAOI drugs tested (iproniazid and isocarboxazid), but not placebo, elevated the ratio of tryptamine:indoleacetic acid in the urine of schizophrenic patients. In another series of experiments, it was found that when methionine loading was combined with a MAOI the increase in excretion of tryptamine in the urine of schizophrenic patients was much greater than the increase produced by the MAOI alone Berlet et al, 1965a;Spaide et al, 1968Spaide et al, , 1969. This effect can be interpreted as the result of a breakdown of body protein or as an inhibition of the tryptophan pyrrolase pathway.…”