tal rats lived with their mothers led to emotional stress of both the mothers and their pups. All evidence of this stress disappeared by the time the pups reached adulthood. However, starting in middle age, these so-called "graduates" of early life stress began to forget the location of objects they had seen before. They also got worse at recognizing objects they had encountered on the previous day. These difficulties worsened as the rats grew older, much more rapidly than in rats that were raised for their first week of life under more nurturing conditions.

In collaboration with Gary Lynch, PhD, and Eniko Kramar, PhD, also of the University of California , Irvine, Brunson and Baram found that communication between brain cells, considered to be the cellular basis for learning and memory, was faulty in the middle-aged rats. Recordings of the electrical activity of brain cells appeared normal in young adult rats exposed to early life stress, but became very disturbed as they reached middle age.

"Now that concrete deficits in brain cell communication have been found in the early-life stressed, demented rats, it may be feasible to find the specific molecules involved and design medicines to prevent the deficits," Baram says.

In other work, researchers showed in rats that stress during the last third of pregnancy affects the ability of adult offspring to respond to challenges to their immune system. Heather Richardson, PhD, and her colleagues Soon Lee, PhD; Dong Seo, PhD, and Catherine Rivier, PhD, at the Salk Institute in La Jolla, Calif., found that the changes in the offsprings' response to immune challenges may be due in part to deficits in nitric oxide, a signaling system in the brain known to connect the immune and stress systems.

Twenty-nine pregnant rats were exposed daily to one of two stresses during the last third of their pregnancies; controls in this group were left alone. Adult female offspring were
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Contact: Leah Ariniello
dawn@sfn.org
202-462-6688
Society for Neuroscience
24-Oct-2004

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