Factor analysis of Forced Swimming test, Sucrose Preference test and Open Field test on enriched, social and isolated reared rats

Developmental and social factors are known to play a crucial role in the pathogenesis of affective disorders. Although it has been demonstrated that early life aversive experiences can be a risk factor in the development of human depression, most of the investigation in animals that try to model depression do not include postnatal manipulations. Since housing represents a fundamental ethological factor which modifies behavior and brain development, this study aimed to investigate the impact of different social and structural housing conditions on the development of a depressive-like syndrome in the behavioral despair paradigm and an anxiety-like syndrome in the unconditioned anxiety paradigm. The present study uses several multivariate analyses to study the impact of housing conditions in animal models of depression and anxiety. In this study, social isolation was able to reproduce the effects found in other animals models based on stress, suggesting that only 2 months of social isolation are enough to produce effects that can be useful as behavioral model of depression. Moreover, environmental enrichment showed an antidepressive and anxiolytic like effect in animal models of depression and anxiety. This effect, which has not been reported in earlier studies, suggests that stimulation during the first stages of growth might play a "protective" role on behavior and brain development. (C) 2005 Elsevier B.V. All rights reserved.