Stanford University neuroscientists have designed a gene that enhances memory and learning ability in animals under stress. Writing in the Nov. 8 issue of the Journal of Neuroscience, the Stanford team says that the experimental technique might one day lead to new forms of gene therapy that can reduce the severe neurological side effects of steroids, which are prescribed to millions of patients with arthritis, asthma and other illnesses.

"Steroids can mess up the part of the brain involved in judgment and cognition," said neuroendocrinologist Robert Sapolsky, co-author of the study. "In extreme cases it's called steroid dementia. Ideally, if you could deliver this gene safely, it would protect the person from some of these cognitive side effects, while allowing the steroid to do whatever helpful thing it should be doing elsewhere in the body."

Sapolsky, the John A. and Cynthia Fry Gunn Professor of Biological Sciences and a professor of neurology and neurological sciences at Stanford, has conducted numerous experiments on the damaging physiological effects of stress and has written extensively on the subject, including a 1995 book, "Why Zebras Don't Get Ulcers."

Hormonal effects

In the Journal of Neuroscience study, Sapolsky and his colleagues focused on the effect of stress on the hippocampus, a part of the brain that's important for learning and memory. Nerve cells throughout the hippocampus contain numerous receptors that respond to a group of steroid hormone called glucocorticoids, which are secreted from the adrenal glands in male and female rats during times of stress. When high levels of these corticoids bind to the hippocampal receptors, they can trigger a destructive biochemical cascade that damages nerve cells in the hippocampus and ultimately impairs memory and learning.

But not all hormones are bad. Estrogen, the primary female sex hormone, enhances memory and can therefore block the negative cogniti
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
7-Nov-2006