How hibernating creatures induce and survive this near-death state, known as torpor, has long fascinated scientists studying animal physiology. More recently, biomedical investigators have also begun to take an interest. In particular, two research groups hoping to unearth novel ways of treating stroke have started to examine how the brains of squirrels endure the rigors of hibernation. They described some of their initial results at the Society for Neuroscience meeting in New Orleans in October. The only proven stroke therapy is prompt use of tissue plasminogen activator, a clot-busting agent, and even that may not help the majority of stroke patients.
Strokes produce waves of brain cell destruction.
The halting of the blood flow stems the brain's supply of oxygen and glucose, immediately slaying a core group of cells. Even after blood flow resumes, additional groups of nearby cells continue to succumb to the stressful event. S everal years ago, Hallenbeck and Kai U. Frerichs of Brigham and Women's Hospital in Boston wondered what happens to blood flow to the brain when squirrels hibernate. The amount of blood reaching the brain plummets by 90 percent or more, the scientists discovered. Consequently, hibernating brains face limited blood-borne supplies of glucose and oxygen, the primary molecules that cells use to generate energy.