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The Integration of Depressive Behaviors and Cardiac Dysfunction During an Operational Measure of Depression: Investigating the Role of Negative Social Experiences in an Animal Model

Grippo, Angela J. PhD; Moffitt, Julia A. PhD; Sgoifo, Andrea PhD; Jepson, Amanda J. BS; Bates, Suzanne L. BA; Chandler, Danielle L. BS; McNeal, Neal BS; Preihs, Kristin BA

doi: 10.1097/PSY.0b013e31825ca8e5
Original Articles

Objective: There is a bidirectional association between depression and cardiovascular disease. The neurobiological mechanisms underlying this association may involve an inability to cope with disrupted social bonds. This study investigated in an animal model the integration of depressive behaviors and cardiac dysfunction after a disrupted social bond and during an operational measure of depression, relative to the protective effects of intact social bonds.

Methods: Depressive behaviors in the forced swim test and continuous electrocardiographic parameters were measured in 14 adult, female socially monogamous prairie voles (rodents), after 4 weeks of social pairing or isolation.

Results: After social isolation, animals exhibited (all values are mean ± standard error of the mean; isolated versus paired, respectively) increased heart rate (416 ± 14 versus 370 ± 14 bpm, p < .05) and reduced heart rate variability (3.3 ± 0.2 versus 3.9 ± 0.2 ln(ms2)). During the forced swim test, isolated animals exhibited greater helpless behavior (immobility = 106 ± 11 versus 63 ± 11 seconds, p < .05), increased heart rate (530 ± 22 versus 447 ± 15 bpm, p < .05), reduced heart rate variability (1.8 ± 0.4 versus 2.7 ± 0.2 ln(ms2), p < .05), and increased arrhythmias (arrhythmic burden score = 181 ± 46 versus 28 ± 12, p < .05).

Conclusions: The display of depressive behaviors during an operational measure of depression is coupled with increased heart rate, reduced heart rate variability, and increased arrhythmias, indicative of dysfunctional behavioral and physiological stress coping abilities as a function of social isolation. In contrast, social pairing with a sibling is behaviorally protective and cardioprotective. The present results can provide insight into a possible social mechanism underlying the association between depression and cardiovascular disease in humans.

Abbreviations: ANOVA = analysis of variance

DSI = Data Sciences International

ECG = electrocardiographic

FST = forced swim test

HR = heart rate

RSA = respiratory sinus arrhythmia

SDNN = standard deviation of normal-to-normal intervals

SEM = standard error of the mean

From the Department of Psychology (A.J.G., S.L.B., D.L.C., N.M., K.P.), Northern Illinois University, DeKalb, Illinois; Department of Physiology and Pharmacology (J.A.M., A.J.J.), Des Moines University, Des Moines, Iowa; and Stress Physiology Lab (A.S.), Department of Evolutionary and Functional Biology, University of Parma, Parma, Italy.

Address correspondence and reprint requests to Angela J. Grippo, PhD, Department of Psychology, Northern Illinois University, PM 357, DeKalb, IL 60115. E-mail: angelagrippo@niu.edu

This research was supported by the National Institutes of Health (Grants MH73233 and MH77581).

Received for publication November 10, 2011; revision received January 27, 2012.

Copyright © 2012 by American Psychosomatic Society
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