MAZE LEARNING AFTER THE ADMINISTRATION OF ANTIDEPRESSANT DRUGS

¹ Department of Pharmacology, Boston University School of Medicine, Boston University Medical Center, Boston, Massachusetts

In order to assess the effects of antidepressant drugs on learning, mice were tested in a single-T water maze after one of the following treatments:control; 1, 2, 4 or 8 mg/kg of d-amphetamine; 100, 200, 400 or 600 mg/kg of iproniazid; 20, 40, 60 or 80 mg/kg of phenelzine; 80, 160, 640 or 1280 mg/kg of deanol; 1,5,10 or 20 mg/kg of imipramine; or 1,5,10 or 20 mg/kg of desipramine. Drugs were administered intraperitoneally 15 mim before testing. Each treatment was replicated with eight independent subjects. A session consisted of 3 adaptation and 30 test trials. Water temperature was maintained between 16 and 19°C. The 80-mg/kg dose of phenelzine produced extreme ataxia. The 8-mg/kg dose of d-amphetamine produced ataxia in some of the animals and disorganized the swimming of the others. As compared to placebo, acquisition was improved after the lower d-amphetamine doses, was not changed after deanol or iproniazid and was impaired after imipramine, desipramine and phenelzine. Swimming speed was improved after the lower d-amphetamine doses and was impaired by nearly all other treatments. The findings from a control study show that the above results cannot be accounted for by an interaction of drug and temperature regulation. The results from this study are compared with the effects of the same drugs on the maintenance of a swimming task.