Grippo, Angela J.
Ph.D. (Doctor of Philosophy)
Department of Psychology
Psychobiology||Behavioral sciences||Social isolation--Health aspects--Research||Heart--Effect of stress on--Research||Serotonin--Social aspects--Research||Serotonin--Effect of stress on--Research
Social relationships positively influence psychological and biological function in humans and other mammals. The disruption of an individual's social environment through separation or death often results in social isolation, which can adversely impact mental and cardiovascular health (Frasure-Smith, Lesperance, & Talajic, 1993; Gore, 1978). The general purpose of this experiment is to further investigate neurobiological mechanisms mediating the adverse effects of social stress and focused on the role of serotonin in that relationship. An animal model was used to simulate social stress in humans. Specifically, the goal of this study is to explore the effects of sertraline hydrochloride (Zoloft) on the behavioral and physiological consequences of disrupted social bonds. We hypothesized that treatment with the antidepressant drug sertraline hydrochloride would buffer the deleterious changes in behavioral and cardiac function following social stress. Specifically, animals administered sertraline hydrochloride were expected to display lower heart rates and higher heart rate variability than the control group (i.e., vehicle only) during basal and behavioral assessment periods. To investigate this, male prairie voles were paired with an unrelated female partner for five days. Following this pairing period, all male prairie voles were isolated for the remainder of the study. After 5 days of isolation, half of the males received sertraline hydrochloride for the remaining 15 days of the experiment. Finally, behavioral assessments were conducted 24 hours apart on the final 2 days of the experiment. This investigation is the first to evaluate cardiac and behavioral responses to antidepressants in the context of social isolation using an animal model.;In general, sertraline hydrochloride was limited in its ability to buffer the negative cardiac and behavioral changes associated with social stress during this experiment. All male prairie voles (regardless of group assignment) displayed a significant increase in heart rate throughout isolation and a decrease in heart rate variability 10 days after isolation, which then recovered to pre-isolation levels. However, isolated male prairie voles administered sertraline hydrochloride did not display a statistically significant reduction in heart rate or increase in heart rate variability as predicted. Further, the sertraline hydrochloride group displayed increased heart rates on days 5 and 10, but not 14, of the drug administration period. The sertraline hydrochloride group's responses during the behavioral tests were mixed. During the tail-suspension test, the sertraline hydrochloride group displayed slightly, but not significantly, lower heart rates and higher heart rate variability than the vehicle group; however, during the forced swim test those results were reversed. Further, in the recovery period immediately following the tail-suspension test, the sertraline hydrochloride group exhibited a longer latency to return heart rate to basal levels, but subsequently displayed a slightly higher heart rate variability, versus the vehicle group.;In conclusion, sertraline hydrochloride treatment was not entirely effective in ameliorating social isolation induced increases in heart rate and depression-relevant behavior. The results of this experiment can help inform our understanding of the mechanisms through which social stress can negatively influence cardiac and behavioral function. Further, these findings contribute new knowledge regarding the utility of the prairie vole model for the study of potential neurobiological mechanisms that underlie the interactions between emotion and cardiovascular function, and how social bond disruption influences that relationship. Future work to extend the present results will improve our understanding of how negative social experiences mediate adverse behavioral and cardiovascular changes that consequently influence quality of life in humans.
McNeal, Neal Daniel, "Social bonds, cardiovascular function, and serotonin : insights from an animal model" (2015). Graduate Research Theses & Dissertations. 4945.
Northern Illinois University
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