A bone hormone helps humans escape

adrenaline is synonymous with anything that makes us boil our blood, whether it's a rattlesnake or watching the latest horror movie. But a new study suggests that when our bodies experience stress responses, epinephrine may not be as important as another hormone, a substance that seeps out of our bones.
, a geneticist at Columbia University, says our bones are not just a rigid stent for the body. Bones in the body secrete a protein called osteocalcin, which was discovered in the 1970s to rebuild bones.
2007, Karsenty and his colleagues discovered that the protein, as a hormone, controls blood sugar levels and burns fat. Later, his team demonstrated that the hormone is essential for maintaining brain function and good health, restoring memory in older mice, and improving the performance of older mice and humans in exercise.
findings led Karsenty to assume that animals evolved bones to avoid danger. This new study is further evidence of this view.
Karsenty and his colleagues exposed mice to several stress factors, including a slight foot shock and a smell of fox urine, a scent that triggers a natural fear response. The researchers then measured osteocalcin levels in the rodents' blood.
study showed that osteocalcin levels increased fourfold in mice within two to three minutes of exposure to a stress factor. A typical stress factor has a similar effect on people -- when researchers ask volunteers to speak in front of some audiences, their levels of osteocalcin soar.
team reported the findings in the September 12 issue of the journal Cell Metabolism.
, Karsenty's team began to determine whether osteocalcin was necessary to trigger a battle or escape pattern, or an unconscious physiological response when an animal faced a threat. This pattern includes an accelerated heartbeat, increased breathing, and elevated blood sugar, a reaction that provides the body with extra energy to prepare it for a quick escape.
when the team exposed genetically modified mice that did not produce osteocalcin to the same stress factors as non-genetically modified mice, the mice showed little response. In normal mice, even without a stress source, a single injection of osteocalcin is enough to trigger an escape or combat response.
studying the neural connections between the rodent brain and its bones, the team found out how osteocalcin triggers battle or escape patterns.
researchers found that when a region of the brain called the amygdala detects danger, it instructs bone cells called osteoblasts to release osteocalcin into the bloodstream. Osteocalcin, in turn, inhibits the activity of the by-emotional nervous system, a nerve fiber that slows heart rate and breathing.
eventually causes the sensory nervous system to stop working, releasing stress responses, including the release of epinephrine, Karsenty said.
karsenty, a researcher at the university, said the results showed that osteocalcin, rather than epinephrine, is the gate keeper who determines when the body enters combat mode or escape mode. The findings also help explain why rodents that have had their adrenal glands removed, as well as those who cannot produce too much adrenaline for health reasons, can still have a strong physiological response to the danger.
Patricia Buckendahl, a bone physiologist at Rutgers University in New Brunswick, New Jersey, who was not involved in the study, said the study was "absolutely news-worthy" and supported the hypothesis that bone evolution was designed to help animals escape predators and other threats.
Buckendahl presented the first evidence 20 years ago that osteocalcin acts as a stress hormone in rats, but no one took the idea seriously at the time. "I've always thought bones weren't just a place to store calcium, "