Strain-specific effects of antidepressants on escape deficits induced by inescapable shock.

The effects of several antidepressants (desmethylimipramine, amitriptyline and bupropion) on escape deficits induced by inescapable shock were assessed in four strains of mice. The extent of the escape interference engendered by inescapable shock varied across strains of mice. These deficits of escape performance were differentially affected by the drug treatments across strains. Repeated administration of desmethylimipramine eliminated the escape interference in A/J, but did not affect the performance in Balb/cByJ, C57BL/6J or CD-1 mice. Bupropion, in contrast, had a modest effect only in CD-1 mice. Unlike these compounds, the 5-HT reuptake blocker, amitriptyline, was found to influence escape performance irrespective of whether the drug was acutely or chronically applied. It is suggested that (a) the relative contributions of various mechanisms subserving the escape interference may vary across strains of mice, hence accounting for the strain-specific effects of the drug treatments, and (b) various antidepressants influence performance by affecting different components of the behavioral output, some of which may be apparent after acute treatment while others are expressed only after repeated treatment with the compound.