Differential paraventricular nucleus activation and behavioral responses to social isolation in prairie voles following environmental enrichment with and without physical exercise

ABSTRACT

Social stressors produce neurobiological and emotional consequences in social species. Environmental interventions, such as environmental enrichment and exercise, may modulate physiological and behavioral stress responses. The present study investigated the benefits of environmental enrichment and exercise against social stress in the socially monogamous prairie vole. Female prairie voles remained paired with a sibling (control) or were isolated from a sibling for 4 weeks. The isolated groups were assigned to isolated sedentary, isolated with environmental enrichment, or isolated with both enrichment and exercise conditions. Behaviors related to depression, anxiety, and sociality were investigated using the forced swim test (FST), elevated plus maze (EPM), and a social crowding stressor (SCS), respectively. cFos expression was evaluated in stress-related circuitry following the SCS. Both enrichment and enrichment with exercise protected against depression-relevant behaviors in the FST and social behavioral disruptions in the SCS, but only enrichment with exercise protected against anxiety-related behaviors in the EPM and altered cFos expression in the hypothalamic paraventricular nucleus in isolated prairie voles. Enrichment may improve emotion-related and social behaviors, however physical exercise may be an important component of environmental strategies for protecting against anxiety-related behaviors and reducing neural activation as a function of social stress.

KEYWORDS:

• Affective behaviors
• hypothalamus
• environmental enrichment
• exercise
• prairie vole
• social isolation

Acknowledgments

The authors would like to thank the following individuals for providing valuable assistance: Ryan Groch, Nicole Holzapfel, Kal Nastek, and Tanya Sheth. The authors also would like to thank Mike Figora and the staff in the Northern Illinois University College of Liberal Arts and Sciences Technical Services Shop for technical assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Preparation of this manuscript was supported in part by Grant No. HL147179 from the National Institutes of Health (National Heart, Lung and Blood Institute) awarded to AJG, and by an award from the Northern Illinois University Office of Student Engagement and Experiential Learning awarded to MC. The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript;National Heart, Lung, and Blood Institute [HL147179]; Northern Illinois University [internal].