Effect of ACTH on the imipramine- and desipramine-induced decrease in duration of immobility time as measured in a rat forced swimming test

In a rat forced swimming test (FS), we examined the effect of repeated inje ctions of ACTH (adrenocorticotropic hormone) for 14 days on the decreased d uration of immobility time produced by imipramine and desipramine. Both imi pramine (15 and 30 mg/kg, p.o.) and desipramine (15 and 30 mg/kg, p.o.) sig nificantly decreased the duration of immobility time in the FS. On the othe r hand, ACTH (100 mug/kg, i.p.) alone did not affect the duration of immobi lity time in FS. When ACTH (100 mug/kg, i.p.) was injected for 14 days befo re the 15-min swim session, it counteracted the decreased duration of immob ility time induced by both imipramine and desipramine. Thus, ACTH seems to play a key role in decreasing the duration of immobility time of antidepres sants in this test. (C) 2001 Elsevier Science Inc. All rights reserved.