Dynamic longitudinal behavior in animals exposed to chronic social defeat stress.

M Wendelmuth,S Schweiger,K Radyushkin,M Willam,H Todorov,S Gerber,Alexandra Kavushansky

doi:10.1371/journal.pone.0235268

M Wendelmuth, S Schweiger + Show 5 more

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https://doi.org/10.1371/journal.pone.0235268

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Abstract

Chronic social defeat (CSD) can lead to impairments in social interaction and other behaviors that are supposed to model features of major depressive disorder (MDD). Not all animals subjected to CSD, however, develop these impairments, and maintained social interaction in some animals is widely used as a model for resilience to stress-induced mental dysfunctions. So far, animals have mainly been studied shortly (24 hours and 7 days) after CSD exposure and longitudinal development of behavioral phenotypes in individual animals has been mostly neglected. We have analyzed social interaction and novel object recognition behavior of stressed mice at different time points after CSD and have found very dynamic courses of behavior of individual animals. Instead of the two groups, resilient or susceptible, that are found at early time points our data suggest four groups with (i, ii) animals behaving resilient or susceptible at early and late time points, respectively (iii) animals that start susceptible and recover with time or (iv) animals that are resilient at early time points but develop vulnerability later on.

Highlights

Major depressive disorder (MDD) is one of the leading causes of disability in Western societies [1]
At T2 both Social interaction (SI) and Novel object recognition test (NORT) exhibited significant deficits in the defeated group, indicated by less time spent in the interaction zone and decreased time spent with the novel object, respectively, compared to the control group (Fig 1c and 1f)
In addition to SI behavior, novel object recognition in a test setting with 24 hours between sample and test phase is impaired in C57BL/6J mice 7 days after the last defeat of a chronic social defeat (CSD) exposure

Summary

Introduction

Major depressive disorder (MDD) is one of the leading causes of disability in Western societies [1]. While chronic stress exposure does significantly contribute to its pathogenesis, not everybody exposed to chronic stress develops MDD [2]. It has been suggested that changes in animal behavior induced by chronic social defeat (CSD) are suitable models for MDD [3,4,5]. In this model, animals are exposed to an aggressor mouse every day for a couple of minutes (5–10 min) over a timespan of 10–21 days. Several animals did not show aversive reaction 1–7 days after CSD exposure, suggesting resilience

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