A study led by researchers at the Massachusetts Institute of Technology and published in Molecular Psychiatry, shows that ghrelin, known as the ‘hunger hormone’ could be involved in the onset of post-traumatic stress disorder (PTSD). Ghrelin was discovered several years ago in obesity research and since then, as it is a hormone that stimulates appetite, pharmaceutical companies have tried to use it as a therapeutic target in the fight against obesity and metabolic syndrome.
Now researchers have found that ghrelin is released also in other conditions such as stress, and that this hormone makes the brain more susceptible to the onset of PTSD. Ki Goosens, an assistant professor of brain and cognitive sciences at MIT and senior author of the paper, said that drugs that lower the levels of ghrelin could be used to protect people who are more prone to PTSD, as are soldiers in the war. Goosens, who is also a member of MIT ‘s McGovern Institute for Brain Research, said it is possible that in the future these people to receive a ghrelin vaccine to have a lower incidence of PTSD. He added that this is an innovation because for the moment nothing is given to these people to prevent PTSD.
Stress is a normal response reaction in dangerous situations that determines the action of ‘fight or flight’. But if stress is chronic, then can lead to other behavioral disorders such as anxiety, depression or other mental illness. In the studies conducted so far, Goosens found that the amygdala, a brain region involved in stress response, has a specific response to chronic stress. It seems that the amygdala produces large amounts of growth hormone during stressful situations, which does not happen in other brain regions. Now researchers have found that the release of growth hormone by the amygdala is controlled by ghrelin. Ghrelin is a hormone produced by the stomach and circulates throughout the body including the brain.
The researchers found that when mice were given a drug to stimulate the ghrelin receptor or gene therapy to express growth hormone for a longer period of time, the mice were more vulnerable to stress and fear than healthy mice. It was found that when mice were exposed to chronic stress, they encoded more strongly the fearful memories. The same thing happens with people who suffer from PTSD. Therefore, researchers want to target the ghrelin receptor to treat or prevent PTSD. “Maybe the ghrelin could get damped down and these people could go through cognitive behavioral therapy, and over time, maybe we can reverse it,” said Retsina Meyer, lead author of the paper.