Carbon monoxide may protect brain from stroke damage

Research conducted on mice suggests that the toxic gas carbon monoxide may help to reduce brain damage caused by stroke.

Sylvain Doré, Ph.D., an associate professor in the Department of Anesthesiology and Critical Care Medicine at Johns Hopkins University School of Medicine, and colleagues induced stroke in mice by temporarily blocking an artery on one side of the brain. After the stroke was induced the researchers exposed one group of the mice to air containing either 125 parts-per-million (ppm) or 250 ppm of carbon dioxide, a second group of mice, which acted as a control, was exposed to air alone.

Results showed that mice exposed to air alone suffered brain damage to 49.9% of the side of the brain where the blood supply had been cut off. In comparison, the extent of brain damage sustained by mice exposed to air containing 125 ppm of carbon monoxide was 33.9%, and in those exposed to air containing 250 ppm of carbon dioxide it was just 18.8%. Neurological function tests were also significantly improved in mice treated with carbon monoxide.

Further studies, in which mice were treated with carbon monoxide one hour and three hours after stroke also produced promising results. The fact that carbon monoxide appears to help protect the brain in the hours following stroke is important as many stroke victims do not receive immediate treatment.

The authors suspect that carbon monoxide's protective effects might be due to a combination of its ability to dilate blood vessels – thus increasing blood flow, its anti-inflammatory properties – which helps to prevent cell death caused by inflammation, and its ability to reduce water in the brain – thus reducing intracranial pressure.

News release: Mouse Studies Suggest “Toxic” Carbon Monoxide May Prevent Brain Damage After Stroke. Johns Hopkins Medicine. December 12th 2008.