Group housing of mice increases immobility and antidepressant sensitivity in the forced swim and tail suspension tests

The forced swim test and tail suspension test are often used in laboratory practice to identify compounds that possess antidepressant-like activity. T his experiment was conducted to determine whether housing conditions per se influence the response of mice in these antidepressant screening procedure s. Male NIH Swiss mice were housed individually or in groups (five per cage ) for 8 weeks prior to testing. After 8 weeks, the animals were exposed to the forced swim and tail-suspension tests. Group housed mice displayed high levels of immobility in the forced swim and tail suspension tests. Desipra mine injection 60 min prior testing, in doses 7.5 and 15 mg/kg, produced si gnificant reductions in the immobility time in forced swimming and tail sus pension tests. Individually housed mice, when exposed to these tests, displ ayed lower levels of immobility with a magnitude comparable to the effect o f desipramine in group housed mice. Desipramine given to individually house d mice did not reduce the duration of immobility either in the forced swim test or in the tail suspension test. These results indicate that both tests are sensitive to housing conditions. This observation suggests that long l asting group housing may be critical to the behavioral response in these pr eclinical screening procedures in mice. (C) 2001 Published by Elsevier Scie nce B.V.