LEXINGTON, KY (Aug. 19, 1998)--A team of researchers from the University of Kentucky and Marquette University has pinpointed distinct patterns of gene expression that indicate stress causes selective increases in production of an inhibitory transmitter in the brains of laboratory animals. These studies provide evidence for a multi-neuron link between brain regions controlling cognition and those regulating hormonal output of the stress system.
Published in the Aug. 1, 1998, issue of the Journal of Neuroscience, the study's results may lead to the development of future stress intervention strategies.
"The interesting thing about human beings is that we're incredibly good at putting ourselves under situations of prolonged stress," said James Herman, associate professor of anatomy and neurobiology and principal investigator of the study.
"The consequences of prolonged stress can range from general malaise to physical or mental illness. The mechanisms controlling stress remain poorly defined, and our studies aim to establish how the brain controls stress responses."
Herman and colleagues believe the brain's stress circuitry is driven by inhibition of certain chemicals, rather than excitation. "For instance, say you walk by a cave 50 times, and nothing comes out. It's an innocuous stimulus," Herman said.
"Inhibitory systems engage to prevent generation of an unneeded, metabolically expensive response. On walk number 51, however, a bear jumps out at you. The part of the brain that says 'this is O.K.' now has a different message -- 'this is dangerous.' The way it does that is through overcoming the ongoing inhibition of the system."
The delicate balance between stress inhibition and excitation is a
survival strategy built into animals through millions of years of evolution,
allowing responses to be generated on demand and quickly turned off. Problems
arise when the system gets changed to such an
Contact: Kim Cumbie
University of Kentucky Medical Center