Chronic Social Defeat Stress Gives Rise to Social Avoidance Through Fear Learning.

Area of Science:

• Neuroscience
• Behavioral Science
• Stress Research

Background:

• Chronic social defeat stress (CSDS) is a rodent model for stress-related disorders.
• Stress-susceptible mice exhibit reduced social interaction after CSDS.
• The role of fear learning in CSDS-induced social avoidance requires further investigation.

Purpose of the Study:

• Investigate the role of fear learning in social avoidance following CSDS.
• Examine fear conditioning mechanisms in 129Sv/Ev mice, a strain vulnerable to CSDS.
• Determine if social avoidance in CSDS is mediated by fear circuits.

Main Methods:

• Utilized 129Sv/Ev mice, a strain more vulnerable to CSDS.
• Assessed social interaction and avoidance behaviors towards CD-1 mice and conspecifics.
• Employed Pavlovian fear conditioning paradigms, including second-order conditioning.
• Investigated extinction of conditioned avoidance through repeated social interaction.

Main Results:

• Defeated 129Sv/Ev mice avoided CD-1 mice but not conspecifics, indicating intact social motivation.
• Mice learned to associate CD-1 mouse coat color with threat, developing conditioned avoidance.
• Avoidance behavior was gradually acquired over 10 days of CSDS and extinguished with repeated social interaction.
• Second-order conditioning led to avoidance of an empty enclosure, demonstrating generalized fear.
• Social interaction variability suggested fear generalization to other social targets.

Conclusions:

• Fear conditioning to a social target is a critical component of CSDS-induced social avoidance.
• CSDS involves fear learning mechanisms that contribute to behavioral deficits.
• Findings implicate fear circuits in the pathophysiology of social avoidance under chronic stress.