VTA-ACC dopaminergic circuit mediates trait anxiety-related observational learning of social avoidance in male mice.

Social animals encounter both environmental and social stress, yet the mechanisms by which individuals with different levels of trait anxiety cope with these stressors, as well as the neurobiological links between trait anxiety and social cognition, remain incompletely understood. Here, male mice are classified into high-trait anxiety (HTA) and low-trait anxiety (LTA) groups based on their anxiety responses to elevated platform exposure in the open field test. Under observational learning-based vicarious social defeat stress (VSDS), HTA mice exhibit less social avoidance behavior toward CD1 aggressors than LTA mice. Fiber photometry reveals that HTA mice display higher activity of ventral tegmental area (VTA) dopaminergic (VTA) neurons during environmental stress, while LTA mice exhibit greater VTA neurons activity under social stress. Viral tracing identifies the connectivity of VTA neurons and anterior cingulate cortex (ACC). Optogenetic and chemogenetic manipulations demonstrate that VTA-ACC dopaminergic circuit is necessary and sufficient for VSDS-induced social avoidance behavior in HTA and LTA mice. RNA-sequencing suggested that VTA neuroinflammatory signaling may be a key factor contributing to the difference between HTA and LTA mice. Thus, this study reveals a neural circuit mechanism for trait anxiety-related observational learning of social avoidance behavior in male mice, and provides a molecular mechanism in shaping trait anxiety.