Repeated treatment with imipramine or amitriptyline increases the locomotor response of rats to (+)-amphetamine given into the nucleus accumbens.

Effects of bilateral injections of (+)-amphetamine (5 micrograms/0.5 microliter) into the nucleus accumbens were investigated in rats treated repeatedly with imipramine or amitriptyline. Repeated but not acute administration of either drug enhanced the locomotor hyperactivity induced by (+)-amphetamine given 2 or 72 h after the last dose of antidepressant. The results indicate that the increased responsiveness of the mesolimbic dopaminergic system may be involved in the action of antidepressant drugs.