Three months before giving birth, the pregnant polar bear retreats to a maternity den dug deep in a snow drift.
There she hibernates, conserving her energy before she has her cubs - and while she suckles them.
During her six-month confinement, the bear does not eat or drink and barely moves. But despite this, her bones remain strong - while large amounts of new bone are made.
This remarkable ability to stop her bones from wasting away could help tackle osteoporosis, scientists believe.
The condition, in which old bone is broken down faster than new bone is made, is most common in old age but can also hit those bed-ridden by ill-health.
If experts can work out how polar bears keep their bones strong during hibernation, they may be able to develop better treatments for osteoporosis, or even drugs to prevent it.
Experts from the Royal Veterinary College, in Hertfordshire, and University College London, have been monitoring 21 pregnant bears in Hudson Bay, Canada.
Only the pregnant animal hibernates. Blood samples showed that they ratchet up bone production before going into hibernation.
Renewal of bone remains high during hibernation - despite the drain on the body of pregnancy, labour and suckling.
As a result, the mother emerges from the den with bones as strong as when she went in, the BBC natural history website LoveEarth.com reports.
Usually, physical activity boosts bone production and bones tend to weaken when animals are immobile for long periods.
Bedridden humans can wait years for their bones to recover.
0 comments:
Trimiteți un comentariu