Effects of mescaline and amphetamine on simultaneous visual discrimination in two inbred strains of mice

Mescaline and amphetamine affect learning and memory differently depending on mouse strain and timing of administration. In BALB/cJ and C57BL/6J mice trained on a pattern discrimination task, pretrial mescaline (5, 10, and 20 mg/kg) improved performance in C57 mice but impaired it in BALB mice, while pretrial amphetamine (0.1, 0.25, and 0.5 mg/kg) improved performance in both strains. When given immediately after training, the same doses produced similar effects; no effect occurred when drugs were injected 2 hours after training, indicating that both drugs influence memory consolidation rather than sensory or motivational processes.

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Abstract

The effects of mescaline and amphetamine were investigated in BALB/cJ (BALB) and C57BL/6J (C57) mice using the five-choice Yerkes--Thompson Bryant--Bovet-Nitti apparatus for patterns discrimination. Two sets of experiments were carried out. In the first set, pretrial administration of mescaline (5, 10, and 20 mg/kg) was followed by performance improvements in the C57 mice, while performances of the BALB strain were impaired by the treatment, as compared with those of the saline-injected (4 ml/kg) controls. The pretrial administration of amphetamine (0.1, 0.25, and 0.5 mg/kg) improved performances of both strains. In a second set of experiments, the same effects as in the pretrial experiments were observed in both strains following administration of mescaline (20 mg/kg) and amphetamine (0.5 mg/kg) immediately after each experimental session. No effect was evident when the drugs were injected 2 h after training, suggesting that effects of the pretrial treatments were due to influences of mescaline and amphetamine on the consolidation processes of the two strains of mice tested.