Flick of a whisker can prevent stroke damage in rats

SAN DIEGO — In the two-hour window after a stroke, flicking a single whisker completely prevents many damaging effects in a rat, a new study finds. The cheap, simple intervention, described November 15 at a news conference at the annual Society for Neuroscience meeting, may represent a new way to minimize disability after a stroke.

“I think it’s one of the most profound findings that have come along in recent years,” said neuroscientist Carol Barnes of the University of Arizona in Tucson. “There is no brain damage. It’s almost a miracle. It’s almost too good to be true. Any protection would be good, but this is more than dramatic.”

Researchers led by Ron Frostig of the University of California, Irvine mimicked a stroke by severing a major blood vessel in rats’ brains. Then at times during the two hours immediately afterward, a mechanical rod stimulated a single whisker on the anesthetized rat for a total of less than five minutes.

With whisker stimulation, the team saw that blood began to flow backward through the severed vessel and got rerouted through other vessels, ultimately reaching the brain area that would have been deprived of blood. No such rerouting was present in rats that didn’t have a whisker stimulated, or in rats that had whisker stimulation more than two hours after the stroke. The team’s preliminary data suggest that the method works for conscious rats, too.

Brain imaging experiments found no evidence that a stroke had even occurred in the whisker-brushed rats. “I have looked at these images for 20 years, and I cannot tell you that this animal went through a major trauma,” said Frostig. “It looks exactly the same” as a scans of healthy rats.

Other tests, including dead tissue stains and behavioral measures, also showed that the sensory stimulation was completely protective against stroke-induced problems. “We didn’t believe it ourselves for a long time,” Frostig said.

The current study was done with young rats, but the team has also found that whisker stimulation protects against stroke damage in 22-month-old rats (the equivalent of 50- to 60-year-old humans). Those results are encouraging, Frostig said, because elderly people are at much greater risk of stroke.

Researchers don’t yet know whether a similar link between sensory stimulation and stroke protection is present in humans. The two-hour sensitive period observed in rats might be a little longer in people because human metabolism is slower than in rats.

The human analogs to a whisker are the lips and fingers, so perhaps sensory input to those regions might confer benefits to someone having a stroke. Lips and fingers are represented very broadly in humans’ brains.

Any stimulation might be useful, Frostig speculates. “If you see a stroke victim, I would sing, I would stroke their face, I would do whatever I can. It can save lives or minimize risks,” Frostig said.

If further studies show similar benefits in humans, such a cheap and powerful method to minimize stroke damage may one day lead to a card, much like a CPR instruction card, telling people how to stimulate stroke victims’ senses immediately after the stroke, Barnes says.