Temporal patterns of repeated acute stress affect stress severity

Open Access
Bao, Alexander D
Area of Honors:
Biobehavioral Health
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Sonia Angele Cavigelli, Thesis Supervisor
  • David John Vandenbergh, Honors Advisor
  • Chronic
  • stress
  • health
  • acute
  • dynamics
  • temporal
Chronic stress has become a growing concern in the modern world, yet since Hans Selye conducted his rat experiments and discovered the negative effects of chronic stress in the 1930s, researchers are still unsure about when acute stress becomes chronic stress and the key characteristics of chronic stress that govern severity. This study was created to investigate whether or not the temporal pattern of acute stressors is an important characteristic that affects physiological and psychological responses to chronic stress. Specifically, we tested whether it is more stressful to experience multiple stressors in a short amount of time (ie. within an hour), or if it is more stressful to experience the same intensity, duration and frequency of stressors spread across the day (ie. across 8hrs). Sixty three male young adult Sprague Dawley rat were used in this study, with 42 rats administered chronic mild stress (CMS) for 4 weeks and 21 as non-handled control animals. Of the 42 chronic mild stress animals, 21 had three CMS stressors administered within an hour (this group is the clumped group), while the other 21 animals had three CMS stressors administered spread across 8 hrs (this group is the distributed group). Clumped animals showed significant differences in weight gain and sucrose preference compared to the control group while distributed animals did not differ in any measurements compared to the control group, suggesting that stressors are more detrimental to health when they are clumped together.