A research published today in the Cell Metabolism journal sheds light on the role of osteocalcin, a substance produced by bones. It is released in response to acute stress: in fact it is therefore a stress hormone.
This typical path of the "fight or flight" mode of different living beings is different and separate from those already known. The latter depend on cortisol, adrenaline and norepinephrine, all produced by adrenal gland.
The discovery helps understand why people and animals sometimes produce acute stress responses even in the absence of cortisol and other molecules.
A revolutionary change
“The fact that bones participate in the stress response is totally new. Exactly like the one that sees the adrenal gland lose the scepter of being the only precious one responsible for this response,” says the study author, Gerard Karsenty of Columbia University Irving Medical Center. “This discovery reinforces the thesis that bones developed in part as a tool to deal with serious dangers. And on a clinical level it confirms the evidence that we react better to dangers when we are young, when our osteocalcin levels are higher."
The acute stress response, better known as the “fight or flight” response, is mediated by the parasympathetic nervous system (I talked about it about a really interesting device). It plays a crucial role in animals' reaction to sudden danger. The adrenal gland, positioned right next to the kidneys (this can also be seen from the name) releases a series of hormones that produce different physiological responses. Increase in body temperature, breathing, blood pressure, heart rate and other mechanisms that prepare the muscles for action.
One of the classic puzzles about stress responses is the characteristic of hormones such as cortisol. It takes hours to affect physiological responses, how could it be used to respond to sudden dangers? “Although this discovery does not exclude hormones glucocorticoids are implicated in some capacity related to the stress response, there is the possibility that other hormones are involved, probably peptide ones,” Karsenty says.
Karsenty and his colleagues suspect that bone-derived hormones contribute to the stress response because the argument matches the history of bone itself.
Structures born to face dangers
Bones protect internal organs from trauma, allow you to trigger more explosive shots and are part of the best listening processes, essential for the prevention of a danger.
Osteocalcin itself is already known for its function of strengthening muscle functions and supporting memory. Two other essential tools to escape from danger and remember a predator.
The laboratory evidence
Lab tests confirmed the research of Karsenty and colleagues: Osteocalcin is the only hormone from bones that increases under stress. In mice subjected to acute stress it grew by 150% in 15 minutes, remaining in circulation for up to 3 hours later. Even in men, circulating osteocalcin increased significantly in tests when volunteers were subjected to stress.
