News Release: Research

Sep. 3,  2008

Yerkes Researchers Create Animal Model Of Chronic Stress

From Woodruff Health Sciences Center News 

In an effort to better understand how chronic stress affects the human body, researchers 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 behavior, physiology and reproduction.

Developing the animal model better positions the researchers to understand the neurohormonal causes of such stress and the body reaction in order to develop more effective treatment options for humans. The study is available in the current online edition of Molecular Psychiatry.

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

Via the animal model, the researchers found corticotropin releasing factor (CRF) is a key neurohormone involved in stress response. Wilson explains, "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."

In response to stress, CRF levels rise; CRF levels decrease when the stressor no longer is present. Chronic stress, however, increases the length and volume of expression of CRF in areas of the brain associated with fear and emotion, including the amygdala. Such chronic stress changes the body's response, and the resulting increased expression of CRF is thought to be the cause of such health-related stress problems including anxiety, depression and infertility.

To study the importance of CRF, the research team 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 behavior, decreased libido and disrupted ovarian cycles suggesting that persistent release of CRF such as occurs in chronic stress clearly affects multiple body systems," says Wilson. "These behavioral changes are similar to what we see in human females who are exposed to stressors on a daily basis." Dr. Wilson and his research team next will attempt 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. Knowing how CRF affects the brain positions the researchers to develop better treatment options.

For more than seven decades, the Yerkes National Primate Research Center, Emory University, has been dedicated to conducting essential basic science and translational research to advance scientific understanding and to improve the health and well-being of humans and nonhuman primates. Today, the center, as one of only eight National Institutes of Health-funded national primate research centers, provides leadership, training and resources to foster scientific creativity, collaboration and discoveries. Yerkes-based research is grounded in scientific integrity, expert knowledge, respect for colleagues, an open exchange of ideas and compassionate, quality animal care.

Within the fields of microbiology and immunology, neuroscience, psychobiology and sensory-motor systems, the center's research programs are seeking ways to: develop vaccines for infectious and noninfectious diseases, such as AIDS and Alzheimer's disease; treat cocaine addiction; interpret brain activity through imaging; increase understanding of progressive illnesses such as Parkinson's and Alzheimer's; unlock the secrets of memory; determine behavioral effects of hormone replacement therapy; address vision disorders; and advance knowledge about the evolutionary links between biology and behavior.

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