Women are twice more likely than men to be diagnosed with depression, and depression is more severe and associated with greater functional impairment in women. However, the neurobiological underpinnings of this increased female susceptibility to depression are unknown. The dopamine (DA) system has traditionally been associated with anhedonia, the inability to derive pleasure from normally rewarding stimuli, and has been recently implicated in the pathophysiology in depression. Importantly, anhedonia is a core symptom of depression and other psychiatric diseases involving DA system dysregulation and characterized by substantial sex differences in their prevalence and nature, such as schizophrenia and drug addiction. Indeed, recent evidence has demonstrated a causal link between a hypofunctioning DA system (i.e. decreased DA neuron activity) and depression-related behaviors (i.e. anhedonia, despair). Surprisingly, little is known about DA system function in females. Thus, characterizing baseline DA system function, as well as stress-induced alterations within this system, is an essential step in understanding sexual dimorphism in the etiology of depression and other psychiatric disorders. Moreover, given the strong link between the DA system and depression, there is a significant potential benefit from novel interventions targeting DA system dysfunction in depression. In sum, the purpose of this proposal is threefold: 1) to define baseline behavioral and DA system function in male and female rats 2) to compare stress-induced behavioral and VTA DA neuron adaptations in male and female rats and 3) to identify potential pathways mediating susceptibility to stressors (i.e. acute, chronic) that differentially impact females. Our overarching hypothesis is that females are more susceptible to the deleterious effects of stress on behavior and VTA activity, and that these effects are mediated by decreased compensation (i.e. activity) in the vSub-NAc pathway. To test this, we will use an integrated systems-oriented approach focused on behavioral assays in vivo electrophysiology, chemogenetics. In this way, we hope to provide a unique perspective on the regulation of the DA system in males and females, the role of the DA system in stress-induced depressive-like symptomatology (i.e. anhedonia, despair), and the mechanisms underlying modulation of the DA system in both sexes under baseline conditions, following acute stress (i.e. post-FST) and after UCMS. Ultimately, these findings could shed light on the increased female vulnerability to depression and lead to the development of novel treatment strategies for depression and other psychiatric disorders implicating aberrant DA system function and anhedonia.

Public Health Relevance

Depression, one of the most prevalent psychiatric disorders, is more common in females. Depression involves reduced activity (i.e. down-regulation) of the dopamine (DA) system, but little is known about the female DA system, how it differs from that of males and whether it is associated with increased vulnerability to depression. In this proposal, we will study DA activity in males and females, how DA activity is altered by stress (a known risk factor for depression) and examine potential pathways mediating susceptibility to stressors (i.e. acute, chronic) and differentially impact females, which may contribute to improved treatments for depression in both sexes.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Postdoctoral Individual National Research Service Award (F32)
Project #
3F32MH110128-01A1S1
Application #
9391422
Study Section
Program Officer
Van'T Veer, Ashlee V
Project Start
2016-12-01
Project End
2017-08-31
Budget Start
2016-12-01
Budget End
2017-08-31
Support Year
1
Fiscal Year
2017
Total Cost
$1,800
Indirect Cost
Name
University of Pittsburgh
Department
Neurosciences
Type
Schools of Arts and Sciences
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Rincón-Cortés, Millie; Gagnon, Kimberly G; Dollish, Hannah K et al. (2018) Diazepam reverses increased anxiety-like behavior, social behavior deficit, and dopamine dysregulation following withdrawal from acute amphetamine. Neuropsychopharmacology 43:2418-2425
Rincón-Cortés, Millie; Grace, Anthony A (2017) Sex-Dependent Effects of Stress on Immobility Behavior and VTA Dopamine Neuron Activity: Modulation by Ketamine. Int J Neuropsychopharmacol 20:823-832