Alteration by Pretreatment with Iproniazid and an Inactive Mescaline Analogue of a Behaviour Change induced by Mescaline

Abstract

THERE have been several conflicting reports on the interaction of mescaline with monoamine oxidase inhibitors. Friedhoff and Goldstein¹, who gave 100 mg/kg iproniazid to rats, 24 h and 3 h before mescaline, found that this pretreatment had no effect on the gross behavioural changes induced by mescaline at 10, 25 and 100 mg/kg. The iproniazid pretreatment itself had produced a slight behavioural excitation at the time of administration of mescaline, and urine estimations of labelled mescaline showed that levels of the unmetabolized amine were considerably increased. In vitro experiments suggest that monoamine oxidase does not affect the metabolism of mescaline. Diamiiie oxidase (histamine oxidase) and a specific mescaline oxidase (found in rabbit liver), however, are probably involved in the oxidation. Iproniazid is not a specific monoamine oxidase inhibitor and is capable of inhibiting both histamine and mescalino oxidase, which would explain the increase in unmetabolized mescaline in urine. Goldwurm and Gualandri (personal communication) found that pretreatment with iproniazid abolished the inhibitory action of mescaline on shuttle box avoidance in the rat. Sbeiner and Sulman² reported that iproniazid given before mescaline in the rabbit induced an anxiety reaction together with EEG changes.