n 3. Stroke of luck
Hibernation: Deeeeeeep sleeeeeeeep


1. Chillin' out

2. Cold trance or transplant?

3. Stroke of luck

4. Waking, meeting, sleeping, mating

Neurologist Cesario Borlongan examines a slice of rat brain that suffered a small stroke. The brain was treated with a protective chemical associated with hibernation in squirrels.Photo courtesy Medical College of Georgia

Calming compound
Strokes -- cell death caused by a blood clot or bleed in the brain -- are a big cause of death and disability. In the United States, these "brain attacks" afflict 700,000 people annually and kill 168,000. More than 1 million stroke survivors are disabled, says the American Stroke Association.

man holds up a clear slide with red spots on itCould a naturally occurring relative of opium that plays a role in hibernation protect brain cells after a stroke?

That possibility arises from work by Cesario Borlongan, an associate professor of neurology at the Medical College of Georgia, through studies of delta opioid, a relative of heroin and morphine. While opioids are known for relieving pain and causing addiction, they can also protect cells from damage. Delta opioid occurs naturally in rodents, humans and other mammals, and it was detected in hibernating squirrels in the 1980s.

Borlongan has been testing delta opioid in rats that had suffered a deliberate stroke, and calls the preliminary results "encouraging... we're seeing significant reduction in the extent of brain damage" and subsequent disability. The compound seems to protect at both ends of the stroke: When the blood supply is reduced (during ischemia), and again when it is restored (during reperfusion). The only side effect noted so far is sleepiness.

Since delta opioid is the first opioid to become active after a brain injury, "we believe it plays a protective role," Borlongan says. Natural levels do not offer good protection, but when delta opioid is dripped into a rat brain after an experimental stroke, cell survival is increased by about 70 to 75 percent.

A bucktoothed, beaver-like mammal huddles in the snow.
The marmot survives the winter by hibernating. Studying hibernators could lead to medical benefits. Photo: National Park Service.

Parking Parkinson's?
Brain cells also die in Parkinson's disease, which damages speech and movement in millions, including Pope John Paul. The disability results from the death of cells that make dopamine, a chemical messenger.

One experimental treatment replaces the dopamine-making cells with fetal cells, but most of the added cells die young.

brain diagram showing death of brain tissue due to lack of blood, and a blood clotStroke is caused by a blood clot or bleeding in the brain. These "brain attacks" kill neurons and can cause major disability. Image: NIH

Could delta opioid protect them? Perhaps. Borlongan and colleagues dunked some cells in a solution containing delta opioid, then transplanted them into rat brains. One month later, 50 to 60 percent more dopamine-making cells were living, Borlongan says, and the animals behaved more normally (more on cell transplants and Parkinson's).

Because delta opioid would treat cells outside the body, and be washed away before transplant, Borlongan says the Parkinson's treatment might be approved sooner than the stroke treatment. Will delta opioid protect human brain cells against stroke? Can it be administered quickly enough to help? Will it have nasty side effects? These questions must receive careful attention before the naturally occurring brain chemical takes its place on the emergency-room shelf.

But if that ever happens, you can thank hibernators for doing more than predicting the weather.

Lighten up! Tell me how a hibernator goes about romancing the opposite sex.


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