Hibernating black bears suggest new paths for tissue preservation

The Arctic Institute of Biology in Alaska recently conducted studies about the hibernation patterns and habits in black bears. One of the keys to successful hibernation is maintaining muscle and bone mass even during long periods when they are not being used. The specific molecular pathway behind this phenomenon in bears is unknown, but research is being conducted to search for a genetic “switch” that could be activated to prevent muscle atrophy. Part of this study was funded by the military who is interested in applying this research to help soldiers recovering from injury that has forced them to be bed-ridden.

Another unique feature in black bear hibernation is that they maintain a relatively high body temperature all throughout the winter. Unlike smaller mammals, black bears only reduce their body temperatures by around 10 degrees Celsius. Animals like squirrels tend to allow their body temperatures to drop to near freezing, but hibernating black bears were observed shivering to raise their body temperature back up anytime it dropped to near 30 degrees. Meanwhile, the bears’ metabolic rates decreased substantially, similarly to in other hibernating mammals. The genetic signal behind the decreased metabolic rate is also unknown, but scientists are trying to unravel this mechanism in hopes that it will lead to many new therapies and medical breakthroughs.

I thought this article was really interesting because it paralleled the discussion we had in class about medical hypothermia and the differences between hibernating bears and other mammals. After hearing about it in class, I really wanted to know how bears are able to sleep an entire winter and maintain a relatively high body temperature and still have a significant drop in their metabolic rates. Like the article said, discovering the factors that cause this process could possibly lead to “suspended animation” of a patient until he or she can receive proper medical care.

Scientific American, February 2011

"Hibernating black bears suggest new paths for tissue preservation," by Katharine Harmon http://www.scientificamerican.com/blog/post.cfm?id=hibernating-black-bears-suggest-new-2011-02-17