Hormone Found in Pregnant Women Can Shield Brain From Injury
by Brendon Nafziger
, DOTmed News Associate Editor | December 28, 2009
Hormone spike during
pregnancy may protect
against traumatic brain injury
Progesterone, a hormone that increases tenfold during pregnancy, is thought to help the developing fetus by protecting it from oxidative stress and aiding neuron development. But a growing body of research leads some doctors to think it could also be a useful first-line treatment after a traumatic brain injury (TBI) or stroke.
In an article published in the January issue of the American Journal of Roentgenology, researchers argue that a spate of recent studies have shown that the hormone might be the first compound after 30 years of testing to protect the brain during acute-stage TBI. And if given to patients in time, the hormone might protect cognitive function and even save lives.
In a recent phase 2 clinical trial with 100 subjects sponsored by the National Institute of Neurological Disorders and Stroke, researchers say patients with moderate-to-severe brain injuries given the hormone intravenously for three days were more than twice as likely to survive: mortality rates were around 14 percent for the hormone versus about 30 percent for placebo.
Another recent study, this one in China with 159 patients, had similar results.
And while the doctors don't know if the findings will apply to humans, work on rats with strokes caused by blocked middle cerebral arteries has shown better brain function following the attack if given the hormone.
This is critical because currently only about 3-5 percent of stroke patients can be treated with tissue plasminogen activators (tPA), a blood thinner that breaks up clots and the only real first-line treatment for strokes currently used. The reason most stroke victims can't get the drug is that doctors have to be absolutely certain the patient is suffering a stroke, otherwise it could cause deadly internal bleeding. And to work, it has to be administered within the first 3½ hours.
Progesterone, by contrast, has shown no adverse effects in any of the studies, and appears to have a wide window, about 24 hours, in which it can work.
How it works
"It's a hormone, in my opinion, that's evolved to protect the fetus," says Donald Stein, Ph.D., a researcher at Emory University and the lead author of the paper. "A lot of mechanisms in repair, not only in the brain but in all highly traumatized tissue, while not identical in development are similar."
The hormone, which can cross the blood-brain barrier, appears to protect neurons in a variety of ways, by preventing injured brain cells from committing suicide and also by blocking the agents that break down their myelin skins. But perhaps most critically, it seems to prevent one of the main dangers of brain trauma: swelling.