Mouse strain differences in the unpredictable chronic mild stress: a four-antidepressant survey

There have been few comparisons of strains and antidepressants in the unpredictable chronic mild stress (UCMS) paradigm in mice. This study was undertaken to determine the influence of such factors using four antidepressants drugs including the tricyclics imipramine (20 mg/(kg day)) and desipramine (10 mg/(kg day)), the tetracyclic maprotiline (20 mg/(kg day)) and the selective serotonin reuptake inhibitor (SSRI) fluoxetine (10 mg/(kg day)) in both Swiss and BALB/c mice. A 6-week UCMS regimen induced deterioration of the coat state and decreased grooming behaviours in the splash test in BALB/c mice but not Swiss mice. The four antidepressants reversed the UCMS-induced effects in BALB/c mice in both measures. However, imipramine and fluoxetine reached significance in the splash test while desipramine and maprotiline displayed only a trend. In conclusion, these results emphasize that BALB/c mice are more sensitive than Swiss mice for studying the effects of the UCMS model as well as for testing antidepressant-like properties.