An Improved Model of Physical and Emotional Social Defeat: Different Effects on Social Behavior and Body Weight of Adolescent Mice by Interaction With Social Support.

Man Li,Hang Xu,Weiwen Wang

doi:10.3389/fpsyt.2018.00688

Abstract

Social stress is a prevalent etiological environmental factor that can affect health, especially during adolescence. Either experiencing or witnessing a traumatic event during adolescence can increase the risk of psychiatric disorders, such as PTSD. The present study attempted to establish an improved social stress model to better distinguish the effects of physical and emotional social stress on the behavior and physiology of adolescent mice. In addition, we investigated how social support affected these stress-induced changes in social behavior. On PND 28, male littermates were exposed to either physical stress (PS) or emotional stress (ES), afterwards, half of them were paired-housed and the others were singly housed. The PS exposed mice were directly confronted with a violent aggressor using the social defeat stress (SDS) paradigm for 15 min/trial (with the total of 10 trials randomly administered over a week), while the ES exposed mice were placed in a neighboring compartment to witness the PS procedure. Our results indicate that both stressors induced an effective stress response in adolescent mice, but PS and ES had differential influence in the context of relevant social anxiety/fear and social interaction with peers. Additionally, social support following stress exposure exerted beneficial effects on the social anxiety/fear in ES exposed mice, but not on PS exposed mice, suggesting that the type of stressor may affect the intervention efficacy of social support. These findings provide extensive evidence that physical and emotional stressors induce different effects. Moreover, ES exposed mice, rather than PS exposed mice, seemed to benefit from social support. In summary, the study suggests that this paradigm will be helpful in investigating the effects of psychological intervention for the treatment of stress-related psychiatric disorders.

Highlights

Adolescence, a transition period between childhood and adulthood, is a critical period for the development of social psychology and the brain [1, 2]
The post hoc analysis showed that both physical stress (PS) and emotional stress (ES) significantly reduced the bodyweight gain under the group housing condition compared to the controls (p < 0.05) and the PS mice experienced the least weight gain
We developed an improved social defeat stress model that could help us further discriminate between the different effects of physical and emotional stress

Summary

Introduction

Adolescence, a transition period between childhood and adulthood, is a critical period for the development of social psychology and the brain [1, 2]. Concomitant with social behavioral manifestations in adolescence, the structure and function of the social brain, which refers to the network of brain regions underlying social emotion and cognition, especially the prefrontal cortex and subcortical pathways, undergo profound and rapid developmental changes [4] These constitute the unique neurobehavioral characteristics of adolescents, that increase their vulnerability to a variety of social stressors [5, 6]. On the other hand, is a common stressor in children and adolescents, shown to be highly predictive of subsequent psychopathology, such as PTSD [16,17,18] Such types of socially stressful experiences in humans can be simulated by the social defeat stress (SDS) model in rodents, typically by the “resident-intruder” paradigm. Due to a common etiological stressor, it is necessary to develop an improved PS and ES model to further clarify the effects of the two types of stressors

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Discussion

Conclusion