State of Hibernation Is Induced in Mice

Eventually, their metabolic rate slowed by about 90 percent, coming virtually to a halt, the researchers reported.

After six hours, the mice were removed from the chamber and placed in a room with regular air. They quickly began to stir, and their metabolic functions began slowly to recover. Within two hours, they were back to normal.

Previous research has shown that the levels of hydrogen sulfide used in the experiment were safe for mice, Roth said. But the researchers subjected the animals to a raft of behavioral and functional tests to see whether there were any detrimental effects. They found none.

"We are, in essence, temporarily converting mice from warm-blooded to cold-blooded creatures, which is exactly the same thing that happens naturally when mammals hibernate," Roth said. "We think this may be a latent ability that all mammals have -- potentially even humans -- and we're just harnessing it and turning it on and off, inducing a state of hibernation on demand."

In addition to the potential medical applications, the findings provide important new insights into the fundamental mechanisms involved in regulating metabolism, experts said.

"People have been trying to understand how animals can induce a metabolically reduced state like this for a long time," said Hannah Carey, a physiologist at the University of Wisconsin at Madison School of Veterinary Medicine. "This is pretty exciting."

Roth and other researchers cautioned that much more research is needed to verify that the approach is safe, and they stressed that it would have to be tested on other species before it is even attempted in people. But they were optimistic.

"It's got great potential," said Samuel A. Tisherman, associate director of the University of Pittsburgh's Safar Center for Resuscitation Research. "All they've done so far is a mouse, so there's a lot more they have to do."