Effects of mescaline on maze learning in the rat

Abstract

This study was undertaken as part of a large-scale long-term investigation of hallucinogenic compounds. The aim was to elucidate the effects of mescaline on original learning and recall of a maze habit by rats.

Literature relating to the chemistry, pharmacology and psychopharmacology of mescaline; the biochemical theories of schizophrenia; the neurophysiological theories of learning; and drug effects on learning and memory, is reviewed.

Three experiments designed to study the effects of 12.5 mg/kg and 25 mg/kg of mescaline after various time intervals; on the acquisition, consolidation and recall of a maze-habit by rats are described and their results are enumerated. The findings are discussed, comparing control and experimental groups at each time interval and dose level, and are related to previous work on the psychopharmacology of mescaline and the effects of central stimulants and depressants on learning.

The following conclusions were reached: i. 12.5 s mg/kg of mescaline administered 0, 15 or 55 minutes before training trials probably inhibits learning during the acquisition phase; this may be due to reduced attention.

ii. 12.5 mg/kg of mescaline injected immediately after training trials does not affect acquisition.

iii. 12.5 mg/kg of mescaline injected 15 minutes before a trial has no effect on recall of a partially acquired habit. Injected 55 minutes before recall it may increase errors and running time.

iv. 25 mg/kg of mescaline injected 15 minutes before training trials does not affect acquisition but markedly retards running speeds. This dose injected 55 minutes before training trials facilitates acquisition. Injected immediately before training it apparently has no effect.

v. 25 mg/kg of mescaline injected immediately after training trials does not affect acquisition.

vi. 25 mg/kg injected 15 minutes before a trial probably inhibits, recall and retards running speed; injected 55 minutes before a trial it has no effect on recall or running speed.

Mescaline's dose-dependent, time dependent facilitating effect on acquisition of a maze-habit was tentatively attributed to a metabolic derivative having this property in common with some of the known CNS stimulants. The drug's retardation effect on motor performance may be dependent on autonomic arousal level.