Researchers find clues about bone deterioration by studying bears

Researchers from Michigan Technological University (MTU) have found clues about disuse osteoporosis in an unlikely place, namely bear bones. Seth Donahue, an associate professor of biomedical engineering at MTU discovered that bears maintain bone formation while they hibernate.

It has long been known that humans and other animals who have long bouts of inactivity may experience bone deterioration. However, Donahue has found that black bears - who hibernate for as many as six months - produce a parathyroid hormone that may maintain bone formation while they sleep.

In order to test whether hibernating bears have biological mechanisms to prevent disuse osteoporosis, Donahue and a team of researchers measured the serum concentrations of hormones and growth factors involved in the animals' bone metabolism, according to the National Center for Biotechnology Information. They then correlated these findings with the serum concentration of a bone formation marker, such as osteocalcin.

Serum was obtained from black bears over a seven month period, which included times of activity and inactivity. Researchers found that resorption and formation markers increased during hibernation, which suggests that high bone turnover occurred during inactivity, the news source reports.

The researchers agree that these findings support the idea that seasonal changes in the concentration of molecules could help regulate bone formation activity and may be important for preventing disuse osteoporosis in bears.

"A synthetic version [of parathyroid hormone] is being used in humans to treat osteoporosis," Donahue told MTU. "But we also believe other molecules are involved, and we're investigating what they might be and the role they play in bone formation."