Exposure to repeated maternal aggression induces depressive-like behavior and increases startle in adult female rats

• Type of Material: Article
• Authors: Chase H. Bourke, Emory University; Gretchen Neigh, Emory University
• Language: English
• Date: 2012-02-01
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2011 Elsevier B.V. All rights reserved.
• License: Creative Commons Attribution-NonCommerical-NoDerivs 3.0 Unported
• Final Published Version (URL): http://dx.doi.org/10.1016/j.bbr.2011.11.001
• Title of Journal or Parent Work: Behavioural Brain Research
• ISSN: 0166-4328
• Volume: 227
• Issue: 1
• Start Page: 270
• End Page: 275
• Grant/Funding Information: GN Neigh receives grant funding from NIMH, AHA, NARSAD, GSK, and Emory University.; Funding for this study was provided by unrestricted funds provided by Emory University’s Comprehensive Neurosciences Center’s Child and Adolescent Mood Program and salary support for CH Bourke was provided by NIEHS Grant T32ES012870
• Keywords: anxiety; lactation; social defeat; stress; depression
• Research Categories: Biology, Physiology; Biology, Neuroscience; Psychology, Behavioral

Abstract

The stress response is a multifaceted physiological reaction that engages a wide range of systems. Animal studies examining stress and the stress response employ diverse methods as stressors. While many of these stressors are capable of inducing a stress response in animals, a need exists for an ethologically relevant stressor for female rats. The purpose of the current study was to use an ethologically relevant social stressor to induce behavioral alterations in adult female rats. Adult (postnatal day 90) female Wistar rats were repeatedly exposed to lactating Long Evans female rats to simulate chronic stress. After six days of sessions, intruder females exposed to defeat were tested in the sucrose consumption test, the forced swim test, acoustic startle test, elevated plus maze, and open field test. At the conclusion of behavioral testing, animals were restrained for 30 minutes and trunk blood was collected for assessment of serum hormones. Female rats exposed to maternal aggression exhibited decreased sucrose consumption, and impaired coping behavior in the forced swim test. Additionally, female rats exposed to repeated maternal aggression exhibited an increased acoustic startle response. No changes were observed in female rats in the elevated plus maze or open field test. Serum hormones were unaltered due to repeated exposure to maternal aggression. These data indicate the importance of the social experience in the development of stress-related behaviors: an acerbic social experience in female rats precipitates the manifestation of depressive-like behaviors and an enhanced startle response.