Project Summary/Abstract
This research will investigate central nervous system mechanisms underlying exercise as a strategy to
promote resilience to social stressors, and is specifically designed to provide a training environment for
undergraduate students. Exposure to social stressors significantly reduces quality of life, contributing to
emotion-related disorders such as depression, physiological disorders such as heart disease, and premature
mortality. However, our understanding of the mechanisms underlying social stressors and potential sex
differences in stress vulnerability and resilience is limited. Therefore, strategies designed to promote resilience
to social stressors in both sexes will improve public health. The present project will use a rodent model – the
socially monogamous prairie vole – to investigate behavioral, autonomic, and endocrine reactivity to long-term
social isolation (Specific Aim 1), and potential molecular and neuropeptide mechanisms that underlie exercise
as a prevention strategy against social isolation (Specific Aim 2). The prairie vole is a valuable model system
for studying responsiveness to social experiences and neurobiological mechanisms underlying stress-related
disorders. This species displays several unique social behaviors that mimic those of humans, including living in
extended families, forming enduring social bonds, and displaying behavioral, physiological, and neural
changes as a function of social stressors. Voluntary exercise may serve a protective role against some
depression-relevant behaviors and endocrine responses in socially isolated prairie voles; however the
mechanisms underlying these benefits are not clear. Therefore, using male and female prairie voles, Specific
Aim 1 will employ continuous recording of autonomic variables (e.g., heart rate, heart rate variability), repeated
corticosterone measurements, and behavioral tests of depression and stress reactivity to test the hypothesis
that exercise is an effective strategy to promote resilience to behavioral and physiological effects of social
isolation in a sex-specific and activity level-specific manner. Specific Aim 2 will employ measures of central
delta-FosB and neuropeptide immunoreactivity, to investigate the hypothesis that long-term alterations in
cortical, limbic, and autonomic brain regions underlie the protective effects of exercise. We hypothesize that
exercise will, in a sex-specific manner: (a) prevent long-term autonomic and endocrine consequences of
isolation; (b) improve behavioral and physiological reactivity to stressors; and (c) improve neural activity in
regions of the brain relevant to social behavior, stress, and autonomic and endocrine processes including the
medial prefrontal cortex, hypothalamus, hippocampus, amygdala, bed nucleus of the stria terminalis, medullary
structures, and dorsal vagal complex. This research proposes novel mechanisms through which exercise can
protect against behavioral and physiological consequences of social isolation. The findings from this project will
facilitate realistic strategies to promote resilience to social stress in both women and men.