Common anesthetic may induce cell death, generation of Alzheimer's-associat...( A new study has found how one of the m...),Health

A new study has found how one of the most commonly used anesthetics may produce Alzheimer's-like changes in the brain. Previous studies have shown that applying the anesthetic isoflurane to cultured neural cells can lead to generation of amyloid-beta protein -- the key component of senile plaques seen in the brains of Alzheimer's patients -- and to the cell-death process known as apoptosis. In the Feb. 7 Journal of Neuroscience, researchers from Massachusetts General Hospital (MGH) and colleagues describe how isoflurane may set off a process in which A-beta generation and apoptosis interact with and magnify each other. Since this work was done in cell cultures, it is unknown whether the findings reflect a possible effect of the anesthetic on human brains.

"Our studies have shown that isoflurane may induce a vicious cycle of apoptosis, amyloid-beta generation, and further rounds of apoptosis leading to cell death," says Zhongcong Xie, MD, PhD, of the MassGeneral Institute for Neurodegenerative Disease (MGH-MIND), the study's lead author. "If future studies support these findings, they suggest that caution be used in choosing this anesthetic for elderly patients, who already are at increased risk for Alzheimer's and for postoperative cognitive dysfunction." Xie is also associated with the MGH Department of Anesthesia and Critical Care.

Alzheimer's disease is characterized by plaques within the brain of amyloid-beta protein (A-beta), which is toxic to brain cells. A-beta is formed when the larger amyloid precursor protein (APP) is clipped by two enzymes -- beta-secretase, also known as BACE, and gamma-secretase -- to release the A-beta fragment. Normal processing of APP by an enzyme called alpha-secretase produces an alternative, non-toxic protein.

Some studies have indicated that general anesthesia may increase the risk of developing Alzheimer's disease. It also is known that a small but significant number of surgical patient
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Contact: Sue McGreevey
smcgreevey@partners.org
617-724-2764
Massachusetts General Hospital
6-Feb-2007