The visible burrow system: A view from across the hall.

Area of Science:

• Neuroscience
• Behavioral Biology
• Stress Research

Background:

• The visible burrow system (VBS) is an ethologically relevant model of social stress.
• VBS induces a distinct dominance hierarchy in rats, impacting brain and behavior differently in dominants (DOM) and subordinates (SUBs).
• Subordinates exhibit significant metabolic changes, including weight loss and imbalance, compared to dominants and controls.

Purpose of the Study:

• To investigate the differential impact of VBS exposure on the brain and behavior of DOMs and SUBs.
• To characterize the distinct phenotypes of stress response within the VBS model.
• To elucidate the neurocircuit mechanisms underlying VBS-induced stress responses and compare them to other chronic stress models.

Main Methods:

• Rats were exposed to the VBS to establish a dominance hierarchy.
• Stress testing was employed to identify different stress response phenotypes (DOMs, stress-responsive SUBs, stress-non-responsive SUBs).
• Gene regulation patterns in the brain, including hippocampal and amygdala expression, were analyzed.

Main Results:

• Subordinates displayed pronounced metabolic changes and distinct stress response phenotypes: stress-responsive (adrenal hypertrophy, elevated corticosterone) and stress-non-responsive (HPA axis hypofunction).
• Brain analysis revealed gene regulation patterns in SUBs indicative of impaired stress inhibition and altered stress pathway drive.
• The stress-non-responsive phenotype was characterized by specific changes in corticotropin-releasing hormone and neuropeptide Y expression.

Conclusions:

• VBS hierarchy formation induces unique neurocircuitry signatures distinct from other chronic stress models.
• The nature of the stressor is critical in understanding stress-related diseases.
• Distinct neurocircuit mechanisms mediate the impact of VBS, suggesting tailored treatment strategies for stress-related disorders.