Short stressful events may improve work...( BUFFALO N.Y. -- Experiencing chroni...)

BUFFALO, N.Y. -- Experiencing chronic stress day after day can produce wear and tear on the body physically and mentally, and can have a detrimental effect on learning and emotion. However, acute stress -- a short stressful incident -- may enhance learning and memory.

Researchers at the University at Buffalo have shown, in trials using rodents as an animal model, that acute stress can produce a beneficial effect on learning and memory, through the effect of the stress hormone corticosterone (cortisol in humans) on the brain's prefrontal cortex, a key region that controls learning and emotion.

Specifically, they demonstrated that acute stress increases transmission of the neurotransmitter glutamate and improves working memory.

"Stress hormones have both protective and damaging effects on the body," said Zhen Yan, professor of physiology and biophysics at UB and senior author on the study. "This paper and others we have in the pipeline explain why we need stress to perform better, but don't want to be stressed out."

The study appeared July 20 in the online edition of Proceedings of the National Academy of Sciences and will be published in an upcoming print version of the journal. Eunice Y. Yuen, Ph.D., UB research assistant professor of physiology and biophysics, is the first author on the study.

To test the effect of acute stress on working memory, Yan, Yuen and colleagues trained rats in a maze until they could complete it correctly 60-70 percent of the time. When the rodents reached this level of accuracy for two consecutive days, half were put through a 20-minute forced swim, which served as acute stress, and then were put through the maze again.

Results showed that the stressed rats made significantly fewer mistakes as they went through the maze both four hours after the stressful experience and one day post-stress, compared to the non-stressed rats.

To determine if the corticosterone
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