Space And Hibernation: Black Bear Holds Key For Future Astronaut Therapy

Decreased physical activity in mammals can lead to significant bone loss and increased fracture risk over time. Yet this is not quite the case for the black bear (Ursus americanus), who is physically inactive for up to six months annually but somehow manages to keep a strong, healthy skeletal structure.

A new study reveals how black bears protect their bones from degrading. Researchers said they believe that studying this creature could help harness treatments against bone-related chronic illnesses and even protecting astronauts on long space flights.

"This could be the basis for a new therapy for astronauts, or people with a bone-related chronic illness," said study author Meghan McGee-Lawrence, assistant professor in cellular biology and anatomy at Georgia Regents University in Augusta, via The Guardian.

For the study, researchers examined 13 female bears between 2006 and 2009, collecting blood and bone samples before, during and after hibernation periods. They then measured enzyme and hormone levels, according to the American Association for the Advacement of Science. 

Researchers discovered that the levels of a bone formation marker called bone-specific alkaline phosphatase (BSALP) and a bone resorption marker known as tartrate-resistant acid phosphatase (TRACP) dropped during hibernation, resulting in decreased overall bone turnover. Scientists also found that calcium levels made in the blood did not change, suggesting that bone composition remains balanced while bone remodeling is suppressed, limiting bone loss, overall.

Furthermore, the study results revealed that the serum concentration of cocaine and amphetamine regulated transcript (CART), a hormone known to reduce bone resorption, was 15-fold higher during hibernation, with serum calcium concentrations unchanged between hibernation and non-hibernation periods.

Researchers noted how these changes allow the black bears to maintain strong skeletal structures without physical activity over long periods; this is due to suppressed bone loss rather than the regeneration of the bone, itself. 

More information regarding the findings can be seen in the Journal of Experimental Biology.