Effect of Forced Swimming on the Performance of the “Water Escape Test”

Abstract

Housing conditions and prior life experiences are known to affect animal behavior and brain regions that regulate important neural and physiological functions, such as memory and stress responses. Stressors of low to moderate intensity can provide an enriched environment and promote cognitive functions. In contrast, exposures of excessive severity and/or duration can lead to maladaptation and distress, altering cognitive functions. Such excessive stressors can thus be used to model pathological conditions and test diverse therapeutic approaches. In this study, we addressed whether inescapable exposure of rats to aversive water environment of the “forced swim test” would interfere with their cognitive performance on the subsequent “water escape” test. The data show that a single exposure to a 15-min forced swim session interferes significantly with the ability to escape the water environment. This is manifested by a significant increase in the latency of diving under the cylinder and a reduction in the proportion of rats capable of completing the test task during the initial session. Additionally, there is a lack of development in diving skills during repeated sessions at 15-minute intervals. These negative effects can persist for at least 2 weeks. The use of the “forced swim” procedure prior to the “water escape” test may, therefore, provide a novel experimental approach to modeling stress-induced cognitive dysfunctions and evaluating the effects of pharmacological agents with potential antidepressant and procognitive properties.