Four related studies from the laboratory of Assistant Professor Monika Fleshner of the University of Colorado at Boulder suggest physiological responses to stress from the brain, hormonal system and immune system are moderated by regular exercise.
Fleshner, of the kinesiology and applied physiology department, said the research team is seeking a "top-down" explanation of how and why regular exercise affects stress. Doctors know that people who exercise regularly are less likely to get sick after stressful situations than those who don't exercise, and that exposure to mental or physical stress increases a person's susceptibility to illness or disease, she said.
Reactions to stress begin in the brain, Fleshner said. In one study led by CU-Boulder doctoral student Justin Hinde, rats that chose to run on a wheel for four weeks prior to experiencing 90 minutes of moderate stress were shown to have changes in stress-reactive brain circuits. This was determined by measuring the amount of Fos protein produced in stress-reactive brain areas.
Rats that had been running on a wheel before stress had lower amounts of Fos protein in the pre-frontal cortex, septum and amygdala of the brain. Fos protein is a neural activation marker produced by activation of the gene known as c-fos. "What these reductions mean to the animals remains unknown, although it could result in less of a sympathetic nervous system response to stress," Fleshner said.
"It appears the stress circuit begins in the brain at the pre-frontal cortex, and that after stress, wheel-running rats have less neural activity in this area than sedentary rats," she said. The results of the CU-Boulder studies will be presented at the Annual Meeting of the Society for Neuroscience Oct. 23 to Oct. 28 in Miami.
A second study led by CU-Boulder doctoral student Taro Smith examined
neuro-hormonal responses to stress. The results indicated regularly exercising
Contact: Monika Fleshner
University of Colorado at Boulder