The effects of housing, dietary changes and chronic restraint stress on body weight and metabolic parameters in the male wistar rat

Abstract

This study examined the effect of prolonged differential housing and/or diet following exposure to chronic restraint stress on body weight, body fat weight, body fat composition and corticosterone, glucose, insulin and leptin levels. To this end, male Wistar rats were individually-housed (IH) or pair-housed (PH) and fed a condensed milk diet (CD) or a mushy rat chow diet (MD) for twelve weeks. Subsequently, all rats underwent chronic restraint stress (CRS) for seven hours/day for four weeks. During CRS, only PH rats fed MD continued to gain weight, while growth of the other groups was stunted. Housing and diet impacted on body fat weights, where PH caused increased retrorenal fat (P<0.001) in rats fed MD, while in rats fed CD, PH gave rise to less visceral (P<0.01) and more interscapular (P<0.05) and retrorenal fat (P<0.001). The CD resulted in more retrorenal (P<0.001) and interscapular fat (P<0.05) in PH rats, with more visceral (P<0.001) and retrorenal fat (P<0.01) in IH rats. Housing influenced only the fatty acid profiles of the liver and subcutaneous fat in rats fed CD. The CD caused differing fatty acid profiles of the liver, subcutaneous fat, visceral fat, interscapular fat and muscle in PH rats, while altering the fatty acid profiles of the liver, subcutaneous fat, interscapular fat and muscle in IH rats. Housing and diet did not result in differences in corticosterone, insulin and glucose concentrations, while both resulted in significantly elevated leptin levels in PH rats fed CD. Therefore the types of housing and diet have various effects on body weight and glucose and fat metabolism following chronic stress. This dissertation is dedicated to My dear parents, Jeff and Avril Ackerman, for their on-going support My loving husband, Brandon, for his encouragement, assistance and patience My children, Elazar Tzvi, Sara Esther, Yaakov Yehuda and Rossi Bear who have been my stress alleviators and Idah Rangwato and Annah Sibanda who are my right-hand ladies and have made it possible to complete this dissertation- Thank you!