Comparison of rats selectively bred for high and low ethanol intake in a forced-swim-test model of depression: Effects of desipramine

This investigation examined if there is a relationship between selective breeding for high or low alcohol intake and immobility in a forced-swim-test (i.e., ''behavioral despair'') model of depression. Time spent immobile in a water-filled cylinder was measured in the alcohol-preferring (P) and nonpreferring (NP) lines of rats, and in the high-alcohol-drinking (HAD) and low alcohol-drinking (LAD) lines. Each rat was tested for 2 10-min trials administered 24 h apart, and pretreatment with saline or desipramine (10.0 or 20.0 mg desipramine/kg b.wt. IF) also was evaluated. Drug was administered immediately after Trial I and again I h before Trial 2. When tested without pretreatment in Trial I or with saline pretreatment in Trial 2, NP rats spent significantly more time immobile than did P rats, but no comparable line differences were found when HAD and LAD rats were tested. Desipramine pretreatment reduced the time spent immobile in rats of the 2 alcohol-nonpreferring lines (i.e., the NP and LAD rats),but had no significant effect in rats of the 2 alcohol preferring lines (the P and HAD rats). These findings do not support the hypothesis that there is a functional relationship between high alcohol drinking and susceptibility to ''behavioral despair'' as measured by the forced swim test. The results with desipramine suggest that selection for high alcohol intake may be associated with insensitivity to desipramine. (C) 1997 Elsevier Science Inc.