Social subordination and estradiol effects on basal and stress-induced stress axis activity in female rhesus monkeys

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 41-52-HPA Axis & Disease States
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-52
Vasiliki Michopoulos*1, Kathy Reding2, Mark E Wilson*3 and Donna Toufexis4
1Emory University School of Medicine, 2Emory University, 3Emory University, Atlanta, GA, 4University of Vermont
Psychosocial stress is a precipitating factor in the emergence of a range of adverse health outcomes in women, including anxiety and depression.  Psychopathology is more prevalent in women than men, suggesting that individual vulnerability to stress-induced disorders is modulated by gonadal hormones including estradiol (E2).  While exposure to chronic psychosocial stress in females can result in the dysregulation of the limbic-hypothalamic-pituitary-adrenal (LHPA) axis and altered behavioral and physiological sensitivity to E2, it remains unclear whether exposure to a social stressor alters E2’s ability to modulate the activity of the LHPA axis. The current study was conducted to assess whether exposure to a chronic psychosocial stressor mediated by social subordination in ovariectomized female rhesus monkeys alters E2’s dose-dependent ability to modulate the LHPA axis following an acute stressor.  Ten socially dominant and 13 subordinate female rhesus monkeys were studied under four conditions: placebo, 2 µg/kg/d of E2, 4 µg/kg/d of E2, and 8 µg/kg/d of E2 for two weeks.  On day 12 of each phase, animals were exposed to the acute stressor of an approach-avoidance (AA) task where blood samples were collected prior to and following stressor exposure to assess basal levels and stress-induced changes in cortisol levels.   Our results show that subordinate females have lower basal cortisol levels than dominant females in the placebo, no-E2 treatment condition.  Treatment with E2 in subordinate females at all doses was sufficient to increase basal cortisol levels to those seen in dominant females.  Furthermore, while exposure to the AA task significantly elevated cortisol levels, it did so independent of social status.  Importantly, the change in cortisol levels due to the AA task was decreased by the 4 µg/kg/d of E2 compared to all other study conditions, but independent of social status.  These data indicate that the social subordination alters E2’s ability to modulate basal LHPA axis activity and suggests that future studies are necessary to determine how hormone replacement with E2 in postmenopausal women interacts with stress background to influence LHPA activity.

Nothing to Disclose: VM, KR, MEW, DT

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Sources of Research Support: NIMH 081816 (DT); NIH RR00165
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