Discriminative stimulus properties of mescaline: Mescaline or metabolite?

Rats trained to discriminate between a mescaline (25 mg/kg) and a saline state in a two-lever operant chamber showed that neither the metabolites 3,4,5-trimethoxyphenylethanol (TMPE), 3,4,5-trimethoxyphenylacetaldehyde (TMPA), nor N-acetylmescaline generalized to the mescaline cue, regardless of pretreatment with aldehyde dehydrogenase or amine oxidase inhibitors. Both inhibitors enhanced the effects of mescaline itself. The findings suggest that a metabolite is not responsible for the interoceptive stimulus produced by mescaline.

Study at a glance

Abstract

The purpose of this study was to investigate possible similarities in the interoceptive stimuli produced by mescaline and its metabolites. Rats were trained in a 2 lever operant chamber to discriminate between the drugged state (mescaline 25 mg/kg) and the nondrugged state (saline). Following acquisition of discriminative response control the rats were pretreated with either saline, aldehyde dehydrogenase inhibitors or amine oxidase inhibitors and tested stimulus generalization produced by i.p. injections of 3, 4, 5-trimethoxyphenylethanol (TMPE), 3, 4, 5-trimethoxyphenylacetaldehyde (TMPA), N-acetylmescaline, mescaline or saline. The results indicated that both aldehyde dehydrogenase and amine oxidase inhibitors enhanced the effects of mescaline, while TMPE, TMPA and N-acetylmescaline failed to exhibit generalization to the mescaline state, regardless of pretreatment. These findings do not indicate the role of a metabolite in the interoceptive cue produced by mescaline.