Protecting The Brain With Hibernation

To treat certain heart attack patients, doctors sometimes rely on something people usually avoid: hypothermia. Cooling a patient’s body to 32–34 ºC for a day or so can prevent brain damage associated with loss of blood flow. One difficulty with the treatment is stifling shivers, which doctors accomplish by giving patients drugs that paralyze or sedate them. Now researchers report a possible way to skip those drugs and make therapeutic hypothermia more practical. Kelly Drew of the University of Alaska, Fairbanks, and colleagues study the neurochemistry of hibernating animals, such as the Arctic ground squirrel. In previous studies, they found that activating the A₁ adenosine receptor (A₁AR) triggers the onset of hibernation, including the suppression of shivering. So they thought that compounds such as N⁶-cyclohexyladenosine, which switch on A₁AR, could enable shiver-free cooling in people and other animals. The researchers gave rats N⁶-cyclohexyladenosine, which suppressed the animals’ ability to regulate their body temperature and allowed the scientists to cool the rodents to 29 °C for a day (ACS Chem. Neurosci. 2015, DOI: 10.1021/acschemneuro.5b00056). After cardiac arrest, the cooled animals had fewer dead neurons in their brains than those that didn’t get the treatment.