Stereotypy and hyperactivity in rats receiving ethanol and a monoamine oxidase inhibitor

The combined administration of tranylcypromine (TCP) and ethanol to rats produced both a marked increase in general locomotion such as walking and running and the appearance of repetitive stereotyped head and trunk weaving, forepaw padding, and circling movements. Pretreatment with p-chlorophenylalanine (pCPA) abolished the stereotyped behaviors. In contrast, animals pretreated with alpha-methyl-p-tyrosine (AMPT) were virtually indistinguishable from those receiving only TCP + ethanol, except for a decrease in running behaviors. The above results are consistent with a serotonergic mediation of these specific stereotypes. The mechanisms by which TCP + ethanol might produce these effects are discussed.