The social fear conditioning-social buffering paradigm: Attenuation of social fear by social buffering is associated with specific gene expression patterns

Background

Social buffering (SB), defined as the attenuation of fear responses to a threatening situation, for instance a threatening social encounter, through the presence of a conspecific, has been demonstrated across species, with human studies highlighting notable sex differences [1]. The social fear conditioning (SFC) paradigm, an animal model of social anxiety disorder, is based on operant conditioning in which animals learn to associate social approach behavior with negative consequences. The paradigm comprises three phases: social fear conditioning (day 1), social fear extinction (day 2), and extinction recall (day 3). Previous studies have shown that neuropeptide Y (NPY) and oxytocin systems regulate social approach and avoidance behavior.

We established a combined SFC–social buffering (SFC–SB) paradigm and demonstrated that multisensory social support from a conspecific allowing physical contact reduces the expression of social fear. Although complete extinction of social fear following the extinction and extinction recall resulted in similar social behavior across groups, gene expression analysis revealed sex and group-specific alterations, particularly in NPY-related genes. However, the extent to which gene expression patterns differ between groups across sexes and groups prior to complete extinction of social fear remains unclear.

Objective

This study examines social fear expression and the associated effects on gene expression patterns across sexes and brain regions in mice with and without social buffering using the established SFC-SB paradigm.

Methods

Adult male and female C57BL/6J mice were assigned to three experimental groups: SFC– (unconditioned), SFC+ (socially fear-conditioned without SB), and SFC+_SB (SFC+ with SB). Following SFC, SFC+_SB mice were housed overnight with a familiar conspecific, while SFC– and SFC+ mice were single-housed. Social fear expression was assessed the next day, with time spent sniffing an unfamiliar same-sex stimulus mouse serving as the primary measure of social fear. Brain tissue was collected 2 hours after testing, and the medial prefrontal cortex, anterior cingulate cortex, insular cortex, septum, hypothalamus, and amygdala were dissected. Gene expression levels of Npy and its receptors, oxytocin and its receptors, serotonin receptors (1a, 2a, 2c), vasopressin and its receptors (1a, 1b), and c-Fos were quantified using real-time PCR. Statistical analyses were performed using two-way ANOVA in R (version 4.4.2) with Bonferroni-adjusted post hoc tests when appropriate.

Results

SFC- mice exhibited normal social exploration during behavioral testing, whereas SFC+ mice displayed a significant reduction in social investigation, indicative of social fear. In contrast, SFC+_SB mice showed a marked increase in social exploration compared to SFC+ mice, suggesting that social buffering attenuates the expression of social fear. Gene expression analysis revealed both sex- and group-specific differences across various brain regions, particularly in areas involved in social behavior regulation.

Conclusion

Social buffering is not only associated with a reduced expression of social fear, but also with changes in gene expression, particularly in key brain regions that regulate social behavior.

References

1. Qi, Y., Bruch, D., Krop, P., et al. Social buffering of human fear is shaped by gender, social concern, and the presence of real vs virtual agents. Transl Psychiatry 11, 641 (2021). https://doi.org/10.1038/s41398-021-01761-5