Adrenaline does not cause the fight or flight response, according to a new study

An exhilarating level when you face a danger, a boost of energy when you opt for an intense race – we tend to associate these rushes with adrenaline, a hormone synonymous with our response to combat or flight. But it turns out that adrenaline may not be what activates the stress response of our brain after all.

In fact, our bones could do more work than expected. A new study, published today in Cell metabolism notes that adrenaline is only one part of our stress response. A hormone called osteocalcin, secreted by our bones, may be more important in life and death situations.

Why bones

You may have heard that bones exist to support and support our body. But for Gerard Karsenty, a researcher at Columbia University's Irving Medical Center and author of the study, we are looking at them the wrong way.

The rigid belief that bones provide only structural support neglects their many additional functions. The bone marrow produces blood cells and stem cells and secretes various hormones that our body needs.

In other words, the perception of bones as empty tubes passing through our body is too simplistic. In fact, Karsenty thinks that bones can be developed for a very different purpose.

"We hypothesize that evolution might have invented the bones as a way to escape danger when animals leave the sea to go to land," he says.

As part of ongoing research into the role of osteocalcin in our body, he and his team exposed mice to stress triggers and measured their hormonal levels. They saw that the levels of osteocalcin and adrenaline were on the rise. However, mice whose adrenal glands were removed still exhibited the classic signs of a fight or flight response, indicating that osteocalcin was probably responsible.

In addition, mice that could not produce osteocalcin barely responded to the odor of a predator's urine. The results convinced the researchers that the hormone we need to push us into panic is actually the one that oozes from our bones.

The issue of adrenaline

So what is of adrenaline in our body? Why is always present when we panic, even if it does not seem to play such an important role in our response to stress?

"We do not know why, we just know what we studied," says Karsenty. "You do not need the adrenal glands to allow a stress response."

The question of the role of adrenaline in the response to stress in our bodies remains open, despite decades of research. Scientists know that this causes the racing of our hearts, sweating of the hands and the increase of blood pressure – and is always present in stressful situations alongside osteocalcin. But the role played by this hormone when we are in danger is perhaps less obvious than we thought.

Maybe the next time you feel this sudden surge of panic, call it rather an osteocalcin push.