Animal model may offer treatment for chronic stress

Washington, Sept 4 : Scientists at the Yerkes National Primate Research Center and the Department of Psychiatry and Behavioral Sciences, Emory University, have created an animal model that shows how chronic stress affects behaviour, physiology and reproduction.

The model will enable them to better understand neurohormonal causes of chronic stress and the body's reaction, which in turn would pave the way for more effective treatment options for humans.

"Chronic stress can lead to a number of behavioral changes and physical health problems, including anxiety, depression and infertility," said lead researcher Mark Wilson, PhD, chief of the Division of Psychobiology at Yerkes.

Using this animal model, the researchers found that corticotropin releasing factor (CRF) is a key neurohormone involved in stress response.

"CRF is located in several different brain regions, serving different functions. Its release is important for our ability to adapt to every day stressors and to maintain our physical and emotional health," explained Wilson.

Stress triggers CRF levels to rise, but CRF levels decrease when the stressor no longer is present. However, chronic stress increases the length and volume of expression of CRF in areas of the brain associated with fear and emotion, including the amygdala.

The chronic stress changes the body's response, and it is believed that the resulting increased expression of CRF is the cause of health-related stress problems including anxiety, depression and infertility.

For studying the importance of CRF, the scientists used a viral vector to increase the production of CRF in the amygdala of female rats.

"In our study, rats that continuously were exposed to CRF from this area of the brain experienced anxious and depressive behaviour, decreased libido and disrupted ovarian cycles suggesting that persistent release of CRF such as occurs in chronic stress clearly affects multiple body systems. These behavioural changes are similar to what we see in human females who are exposed to stressors on a daily basis," said Wilson.

Now the researchers will try to learn more about the negative effects of increased CRF by examining actual molecular and cellular changes in specific brain areas targeted by the neurohormone.

The knowledge of how CRF affects the brain positions, will help the researchers to develop better treatment options.

The study is available in the current online edition of Molecular Psychiatry.

ANI