Stress can make otherwise minor challenges feel much worse, with detrimental effects on health and behavior. In the May issue of Nature Neuroscience, French researchers describe a molecular pathway in the brain by which stress enhances the response of mice to negative experiences.
Pier Vincenzo Piazza and colleagues found that corticosterone, a stress-induced hormone, strongly activates a set of signaling molecules, the so-called "MAP kinase cascade", in the hippocampus, a brain structure that is essential for learning and memory in both mice and people. Mice act frightened when put into a chamber where they have previously had an unpleasant experience. This fear response was increased by stressful conditions, or by injection of extra corticosterone.
The researchers observed that the exaggerated fear response was absent when they blocked the MAP kinase cascade in the hippocampus of corticosterone-injected mice.
Pier Vincenzo Piazza (Université de Bordeaux II Domaine de Carreire Saens, Bordeaux, France)
Also available online.
(C) Nature Neuroscience press release.
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