Social stress has adverse consequences for physical and mental health throughout life and its impact may be particularly relevant during adolescence as this is a time of substantial growth and reorganization of brain circuits. Social stress also has a differential impact in females compared to males though most research has focused on males. The proposed research uses the resident intruder model of social stress that we refined to understand how individuals cope during repeated social stress and how this determines individual consequences of repeated social stress for behaviors associated with depression and impaired cognitive function. Our research focuses on the locus coeruleus (LC) norepinephrine system, a major stress response system that mediates arousal and cognition in response to stress. The working hypothesis that frames this research is that individual differences in stress vulnerability result from differences in the circuitry that is engaged to regulate LC activity during stress. Specifically, excitatory regulation of the LC by corticotropin-releasing factor (CRF) and orexinergic afferents is hypothesized to underlie a passive coping style and vulnerability to stress-related disorders that are characterized by hyperarousal. In contrast, inhibitory enkephalin inputs to the LC are counterregulatory and are associated with a more active coping strategy and decreased vulnerability to those disorders. We hypothesize that LC-activating inputs and LC- inhibiting inputs are differentially altered in development and between sexes. This hypothesis is tested in 3 specific aims using technical approaches that include cellular measurements of receptor expression and trafficking, in vivo electrophysiology in behaving rats, chemogenetic manipulation of circuits using DREADDs and assessment of cognitive function and behavior.
Aim 1 will identify stress-induced plasticity in circuits that regulate LC activity and how this is dependent on age and sex.
Aim 2 will use DREADDs and neuropharmacological techniques to directly test the role of LC activity and its CRF, orexin A and enkephalin afferents in coping strategy in response to social stress.
Aim 3 will test the role of the LC and its afferents on the pathological consequences of social defeat, including anhedonia, morphine conditioned place preference and cognitive function in the attention set-shifting test. Because coping strategy is an important determinant of stress resilience, the results of the proposed studies will significantly increase our understanding of how coping strategy can optimize activity of the LC-NE arousal system. The results will inform therapies designed to modify coping strategy in an effort to promote resilience and whether these therapies should be different depending on age and on sex.

Public Health Relevance

The goal of this research is to elucidate the neurobiological mechanisms by which individuals cope with social stress during adolescence and adulthood using a rat model of social stress. The proposal examines how these mechanisms shape coping during stress and the subsequent consequences of stress on behavior and cognitive function. By performing studies in both male and female rats, the basis for sex differences in vulnerability to and the developmental trajectory of stress-related psychiatric disorders will be identified.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Research Project (R01)
Project #
5R01MH093981-07
Application #
9313932
Study Section
Biobehavioral Mechanisms of Emotion, Stress and Health Study Section (MESH)
Program Officer
Simmons, Janine M
Project Start
2011-09-15
Project End
2019-04-30
Budget Start
2017-05-01
Budget End
2018-04-30
Support Year
7
Fiscal Year
2017
Total Cost
Indirect Cost
Name
Children's Hospital of Philadelphia
Department
Type
DUNS #
073757627
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Wellman, Cara L; Bangasser, Debra A; Bollinger, Justin L et al. (2018) Sex Differences in Risk and Resilience: Stress Effects on the Neural Substrates of Emotion and Motivation. J Neurosci 38:9423-9432
Wood, Christopher S; Valentino, Rita J; Wood, Susan K (2017) Individual differences in the locus coeruleus-norepinephrine system: Relevance to stress-induced cardiovascular vulnerability. Physiol Behav 172:40-48
Bangasser, D A; Dong, H; Carroll, J et al. (2017) Corticotropin-releasing factor overexpression gives rise to sex differences in Alzheimer's disease-related signaling. Mol Psychiatry 22:1126-1133
Urban, Kimberly R; Valentino, Rita J (2017) Age- and Sex-Dependent Impact of Repeated Social Stress on Intrinsic and Synaptic Excitability of the Rat Prefrontal Cortex. Cereb Cortex 27:244-253
Zitnik, Gerard A; Curtis, Andrè L; Wood, Susan K et al. (2016) Adolescent Social Stress Produces an Enduring Activation of the Rat Locus Coeruleus and Alters its Coherence with the Prefrontal Cortex. Neuropsychopharmacology 41:1376-85
Reyes, Beverly A S; Zitnik, Gerard; Foster, Celia et al. (2015) Social Stress Engages Neurochemically-Distinct Afferents to the Rat Locus Coeruleus Depending on Coping Strategy. eNeuro 2:
Snyder, Kevin; Barry, Mark; Plona, Zachary et al. (2015) The impact of social stress during adolescence or adulthood and coping strategy on cognitive function of female rats. Behav Brain Res 286:175-83
Snyder, Kevin P; Barry, Mark; Valentino, Rita J (2015) Cognitive impact of social stress and coping strategy throughout development. Psychopharmacology (Berl) 232:185-95
Wood, Susan K; Zhang, Xiao-Yan; Reyes, Beverly A S et al. (2013) Cellular adaptations of dorsal raphe serotonin neurons associated with the development of active coping in response to social stress. Biol Psychiatry 73:1087-94
Bangasser, Debra A; Lee, Catherine S; Cook, Philip A et al. (2013) Manganese-enhanced magnetic resonance imaging (MEMRI) reveals brain circuitry involved in responding to an acute novel stress in rats with a history of repeated social stress. Physiol Behav 122:228-36

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