A new study has found that bone plays a role in fight or flight response. Adrenaline is considered vital for triggering this response. But this recent research has revealed the importance of bone in fight or flight response.
And showed that this mechanism can’t work without a hormone made in bone. The journal “Cell Metabolism” has published this research on September 12, 2019.
Osteocalcin is necessary for initiation of fight and flight response
When a person faces a sudden danger, the fight or flight response gets initiated. The breathing becomes more rapid, heart rate increases and glucose as fuel is pumped throughout the body. All of these prepare an animal to fight or flee a sudden danger. Previously, the scientists considered adrenaline as a trigger for fight or flight response.
But this new study has suggested that bony vertebrates can’t give this response without the skeleton. The research team has found that once realizing a danger, the brain stimulates the skeleton to flood the bloodstream with osteocalcin. That is a bone derived-hormone. And is responsible for the initiation of the fight or flight response.
Previous research has revealed that the bony skeleton releases osteocalcin. This hormone enters the blood and affects the functions of the biology of many other organs. That may include the pancreas, muscles, and the brain. After this research, a series of studies have indicated that osteocalcin has a role in regulating metabolism.
It can increase the cell’s ability to take in glucose, improve memory and also help animals in running faster with greater endurance. But if osteocalcin mediates the acute stress response, it should work fast during the first few minutes after detecting danger.
The acute stress response can be seen in the absence of adrenaline
In this study, the research team has exposed mice to predator urine and some other stressors. And observed the changes in their bloodstream. Within the first 2 – 3 minutes, they saw a spike in the levels of osteocalcin.
The results were similar in the case of humans. The research team found there was a rise in the osteocalcin levels after exposure to stress in the people. While the stressors may include public speaking or cross-examination.
Further study showed a rise in the heart rate, blood glucose levels, and body temperature of the mice with increased levels of osteocalcin. In contrast, genetically engineered mice that were unable to make osteocalcin or its receptors were unresponsive to the stressors.
They didn’t respond strongly to the danger due to the absence of the osteocalcin. But these mice were able to bring on fight or flight response when injected with large amounts of osteocalcin. These findings have also explained why adrenal-insufficient patients (with no means of producing adrenaline) can develop an acute stress response.
On the other hand, the inability to make large amounts of osteocalcin in mice has led to the disappearance of fight or flight response. Overall, the study suggests that levels of osteocalcin circulating in the blood can drive the acute stress response. And this response can occur even with the absence of hormone adrenaline.