Effects of Repeated Acute Stress in Obese and Non-Obese Rats
Abstract
Stress is pervasive among all people. Roughly 65% of American adults are overweight or obese. Because stress and excess body weight each has deleterious mental and physical health effects, it is relevant to determine whether the two conditions exacerbate each others' effects. This doctoral research project examined responses to stress in male and female, lean and obese rats. Two separate experiments examined behavioral and biological effects of repeated acute stress as a function of body weight, diet, and sex. Experiment I manipulated genetic and environmental variables to examine effects of repeated acute stress on obese and non-obese male rats. Experiment II examined effects of repeated acute stress on genetically obese and non-obese male and female rats. In Experiment I, stress: (1) decreased bland food consumption in lean and obese rats; (2) altered cafeteria food consumption; (3) reduced caloric consumption in most groups; (4) increased blood corticosterone levels, especially among lean rats re-exposed to stress; (5) increased physical activity among lean rats; and (6) increased startle responses among lean rats but impaired attentional processing among animals fed cafeteria food. In Experiment II, subsequent to stress (i.e., post-stress): (1) prior stress exposure resulted in lower corticosterone levels compared to a no-stress history, especially among obese rats; (2) startle responses among lean males increased; (3) percent pre-pulse inhibition of startle increased among lean stressed females but decreased among obese stressed females. Together these findings indicate that obese rats were less reactive to stress. The interpretation of these findings is that obesity is associated with maladaptive stress responses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 02, 2008
- Accession Number
- AD1013781
Entities
People
- Christie O. Simpson-mckenzie
Organizations
- Uniformed Services University of the Health Sciences