Behavioral and biological effects of housing conditions and stress in male rats -- relevance to heart disease /

by Shafer, Sarah T

Title of Thesis: “Behavioral and biological effects of housing conditions and stress in male rats -- Relevance to heart disease” Author: Sarah T. Shafer, Master of Science, 2006 Thesis directed by: Neil E. Grunberg, Ph.D., Professor Department of Medical and Clinical Psychology The present experiment examined the effects of environmental enrichment and stress on behavioral and biological measures relevant to cardiovascular disease risk (i.e., plasma corticosterone levels, elevated plus maze, locomotor activity in an open field chamber, body weight and food consumption, and heart morphology). Seventy-two Sprague-Dawley rats were raised in enriched environments (social or social and physical enrichment) or non-enriched environments for a total of 48 days. Half of the animals were placed in stress conditions in which they received 14 days (20 minutes/day) of restraint stress and the other half of the animals were placed in a no-stress condition. Results revealed that : (1) rats in the stress condition had increased plasma corticosterone levels compared with non-stressed rats, (2) rats in the enriched group had decreased open-field locomotor activity and increased habituation to a novel environment compared with non-enriched rats, (3) rats in iv the stress and enrichment groups had decreased body weight and food consumption compared with non-stressed and non-enriched rats, (4) rats in the stress with social enrichment conditions had heart dimensions that differed from rats in the other stress conditions without social enrichment. Social enrichment appeared to attenuate some effects of stress on the heart. These findings and future research are discussed with regard to risk for cardiovascular disease. v Behavioral and Biological Effects of Housing Conditions and Stress in Male Rats -- Relevance to heart disease by Sarah T. Shafer Master’s Thesis submitted to the Faculty of the Department of Medical and Clinical Psychology Graduate Program of the Uniformed Services University of the Health Sciences in partial fulfillment of the requirements for the degree of Master of Science, 2006 vi