Blockages in the arteries feeding the brain can cut off blood and oxygen to nerve cells just as clogged coronary arteries can stop blood flow to heart muscle. For that reason, these ischemic strokes are now called "brain attacks," analogous to heart attacks.

But even after a stroke, when blood flow to the brain has been restored, the damage to brain cells can continue for several more days. That's because the absence of oxygen and glucose signals a chemical chain reaction in the cells that leads to the production of damaging free radicals. This phenomenon, called delayed neuronal death, causes neurological symptoms to worsen in about a third of patients in the days following a stroke.

Working with Qun Wang, an MU postdoctoral fellow in biochemistry, the Suns used Mongolian gerbils to test the effectiveness of resveratrol in preventing delayed neuronal death. Gerbils are widely used as an animal model for stroke because a unique quirk in their anatomy makes it easier for researchers to induce strokes than in many other kinds of lab animals. Humans and other mammals have a ring of connecting arteries, called the circle of Willis, at the base of their brain.

In gerbils, that circle is incomplete and lacks the connection between the front and back of the brain. This ensures that cutting off blood flow to the carotid arteries in a gerbil's neck causes a stroke at the front of the animal's brain.

The researchers induced strokes by anesthetizing the gerbils, exposing their two carotid arteries, closing off circulation with clips and then reopening the arteries five minutes later. Some of the animals received injections of resveratrol either during or just after strokes were induced.

Four days later, the researchers examined the animals' brains. Microscopic images showed substantial numbers of dead neurons in the brains of gerbils that had not received resveratrol. But in gerbils that had received the compound, the damage clearly was minimized. The next question the Suns asked, according to Grace Sun, was this: "If we put polyphenols in our diet, is that good for stroke?"

The search for an answer began when the Suns obtained a standardized grape extract from the California Table Grapes Commission for another series of experiments that are now underway. They gave gerbils the freeze-dried grape powder as a drink once a day for four days before inducing strokes. Subsequent examination showed the extract had, in fact, minimized brain damage.