The study was conducted at Oregon Health & Science University (OHSU) and Portland Veterans Affairs Medical Center (PVAMC).
In order to determine the effect of Prazosin, the researchers administered a glucocorticoid called dexamethasone to rats, then measured the expression of a protein known as heat shock protein 70, or HSP70, that serves as a marker for neurotoxicity.
Pretreatment with prazosin, an alpha-1 receptor antagonist, resulted in "significant" slowing of dexamethasone-induced expression in the cerebral cortex.
According to the researchers, Prazosin is an antipsychotic medication that appears to block the increase of steroid hormones known as lucocorticoid and is also responsible for the attenuating dexamethasone-induced HSP70 expression in the cortex.
Elevated levels of glucocorticoids are associated with atrophy in nerve branches where impulses are transmitted, and even nerve cell death, in the hippocampus - which is the elongated ridge located in the cerebral cortex of the brain where emotions and memory are processed.
The study states that low levels of glucocorticoids have anti-inflammatory effects in the brain, while high levels can trigger inflammatory mechanisms that damage nerve cells by activating an enzyme that causes oxidative stress. Even a single exposure to a high dose of glucocorticoids can be sufficient to damage nerve cells.
"It's known, from human studies, that corticosteroids are not good for you cognitively. We think prazosin protects the brain from being damaged by excessive levels of corticosteroid stress hormones," said study co-author S. Paul Berger, M.D., assistant professor of psychiatry and behavioral neuroscience, OHSU School of Medicine and the PVAMC.
"The one thing we don't know for sure is, would you have to get it before you're traumatized. Lots of people have high levels of corticosteroids when they're under stress, so could we give them prazosin ahead of time to protect them from brain damage?" Berger said.
The study was funded by the U.S. Department of Veterans Affairs and presented at a poster session at Neuroscience 2007 on November 7, the annual Society for Neuroscience conference in San Diego.