Tufts University  |  School of Arts and Sciences  |  Department of Biology  |  Find People  | 


Responses to Chronic Stress

A major focus of our lab is in trying to understand chronic stress. Although acute stress responses are thought to help an animal survive, when those acute responses are continually activated, or activated for long periods, the stress response starts to cause problems. This is the genesis of stress-related disease and is usually called chronic stress.

We have discovered that chronic stress can have two opposite effects on the ability of animals to cope. In some cases, the glucocorticoid and fight-or-flight systems are ramped up. This can result in metabolic problems and cardiac disease. In other cases, however, both the glucocorticoid and fight-or-flight systems are greatly damped. Either response could be devastating to free-living animals. In the first case, chronic stress will cause animals to suffer from stress-related diseases, much like humans do. In the second case, the damping of the stress response will likely make the animals less able to cope with subsequent stressors. Work in our lab is currently trying to understand the underlying mechanisms for both responses.

We have a number of projects currently underway, both in the lab and in the field. One field project is a collaboration with Loren Hayes at University of Tennessee-Chatanooga and Luis Ebensperger at the Universidad Catolica in Chile. We are exploring whether degus, small South American rodents, use plural breeding and allonursing (females nursing pups other than their own) to buffer their pups from chronic stress.

A second series of projects has been attempting to determine whether corticosterone can be detected in bird feathers. Steroids can be deposited in hair, and we’ve been trying to detect whether they are deposited in feathers. If we are successful, we have the potential of using feathers to determine whether a bird has been chronically stressed. Since the evidence will be in the feather, it creates the possibility that we don’t even need the bird present to diagnose a stressed bird.

Another major series of projects explores whether different types of stressful stimuli are equally able to induce chronic stress. The goal is to understand whether human-induced environmental changes will create the same symptoms of chronic stress in the field as they do in the lab.