Scientists already knew that in case of danger, humans and animals have the reflex of “fight or flight”, motivated by hormones released by the adrenal glands and by nerve pathways directly connected to the brain. But our bones would also have this ability.

Osteocalcin

During a study published in Cell Metabolism On Thursday, September 12, 2019, researchers at Columbia University and Melbourne discovered that bones also release a hormone when faced with imminent danger. This hormone released by the bones is called osteocalcin. Gerard Karsenty, a researcher at Columbia University, and his colleagues found that this hormone helps coordinate our fight-or-flight response.

You should know that in the face of a sudden threat, our heart and respiratory rates, blood pressure, blood sugar and even our body temperature increase to prepare our muscles to fight or flee. The researchers observed that osteocalcin blood levels increased rapidly in humans during stressful speaking, but also in mice and rats when the latter were attached, had received electric shocks or were exposed to water. smell of fox urine.

Our bones may have evolved to protect us from extreme danger

Other research on mice also found that this increase in osteocalcin levels caused the body’s resting and digestive functions to shut down in order to allow the body to prepare for fight or flight. These findings follow previous research by the group showing that bones release osteocalcin to help muscles burn calories during exercise, and that injections of this hormone in elderly mice rejuvenated their muscles.

According to Karsenty, cited by New Scientist, these results suggest that we need to rethink the way we view our bones. If previously our skeleton seemed to us to be an essentially inert structure, this study reveals that our bones may have evolved to protect us from extreme danger by activating the fight-or-flight response, optimizing muscle function, providing the necessary structural framework for movement and flight and forming a protective cage around our organs. Our body has different ways of preparing us to face danger.

However, scientists wonder why the body has three pathways through which the flight or fight option is activated: through the bones, the direct nerve pathways, and the adrenal glands.

According to Robin McAllen of the University of Melbourne, this may be to prevent one of the pathways from malfunctioning. It turns out that this flight or fight reaction always kicks in, even in people with defective adrenal glands and in mice without adrenal glands.