Effects of phenylethylamine on rat locomotor behavior and avoidance learning.

1. The effects of beta-phenylethylamine (PEA) alone and in association with caroxazone, a potent inhibitor of monoamine oxidase B (MAO B), on the activity and long-term memory in the wheel-shaped activity monitor and on fixed-interval two-way avoidance acquisition were studied in rats. In a separate study, we determined the effects of PEA and of d-amphetamine on the variable-interval two-way avoidance acquisition. 2. The action of PEA was markedly different from that of amphetamine in several aspects. The stimulating effects of PEA in the wheel-shaped activity monitor were of a more subtle nature than those of amphetamine and in the variable-interval two-way avoidance acquisition PEA had no effect, while amphetamine improved performance. 3. PEA did not induce an increase in path-choice stereotypy, but caroxazone did. The absence of any caroxazone-session interaction effects on the path iteration frequency suggested that there were no long-term memory effects. 4. In the fixed-interval two-way avoidance acquisition experiments, PEA increased the avoidance responses of rats while caroxazone had no effect. The association of the two drugs did not potentiate either.