The peripheral administration of tetrabenazine (TBZ) induces rapid depletion of brain regional concentrations of norepinephrine (NE), dopamine (DA) and serotonin (5-HT). With respect to both dosage and time, striatal DA was most sensitive to the effects of TBZ while hypothalamic NE was least affected. Pretreatment with the monoamine oxidase (MAO)-inhibitor, clorgyline (1-6 mg/kg) dose-dependently prevented the reduction of all three monoamines for up to 60 min after TBZ (3 mg/kg). The TBZ-induced depletion of cortical NE was also significantly antagonized by desmethylimipramine (DMI) but was of shorter duration (up to 30 min after TBZ). DMI, however, did not influence the effect of TBZ on striatal DA or hypothalamic 5-HT. The protective effects of both clorgyline and DMI were also evident under the conditions of the behavioral TBZ test utilizing high doses of TBZ (20 mg/kg).