Development, validation, and characterization of a novel preclinical animal model of social familiarity-induced anxiolysis

Abstract

Social support is a powerful therapeutic against fear and anxiety and is utilized in many psychotherapies. The concept that a familiar or friendly presence helps a person learn to overcome anxiety has been well-known for decades, yet, the basic neural mechanisms that regulate this psychosocial learning remain unknown. A first step towards elucidating these basic mechanisms is the development of a valid preclinical animal model. However, preclinical behavioral models exploring the use of a social presence in reducing anxiety have not been fully characterized. Therefore, it was our goal to identify a useful way in which to study the mechanisms of how a social presence can induce anxiolysis (the reduction of anxiety). We accomplished this goal by characterizing and validating a preclinical model, as well as demonstrating that the model was capable of measuring deficits in rats given a mild traumatic brain injury. To this end, we identified an existing, but uncharacterized model, the social interaction-habituation model, as an effective model of social familiarity-induced anxiolysis (SoFiA), which demonstrates socially enhanced safety learning, or psychosocial learning. We find that as social familiarity develops across time, anxiolysis develops. We identified that the use of a Bright Light Challenge is a useful anxiogenic stimulus to use during SI-habituation training. The anxiolysis acquired following SI-habituation testing is partner specific, and can be blocked by an inhibition of the medical prefrontal cortex, while it can be enhanced by D-cycloserine. We found that this model identified deficits in SoFiA acquisition in rodents exposed to a mild traumatic brain injury, which, in humans, has been linked to psychosocial deficits. This work is a step in creating ways in which we can study and better understand the regulatory processes of emotions mediated by social behavior.