Effects of iproniazid and tranylcypromine on the half-life of N,N-dimethyltryptamine in rat brain and liver

The time course of N,N-dimethyltryptamine (DMT) levels in brain and liver of adult male Holtzman rats was determined with and without pretreatment with the monoamine oxidase inhibitors iproniazid (32 mg/kg) and tranylcypromine (10 mg/kg) given i.p. DMT was given in doses of 1.0, 3.2 and 10.0 mg/kg i.p. DMT was assayed spectrophotofluorometrically and in some instances by a radioisotopic method. The results show that the half-life of DMT varied with different doses in the brain but not in the liver. Pretreatment with the monoamine oxidase inhibitors prolonged the total period during which DMT was found. A linear relationship exists between the mean time required to reach minimal DMT concentrations and the mean duration of suppression of FR₄ barpressing behavior in rats trained for a milk reward. The results suggest a direct involvement of DMT in inducing behavioral toxicity.