Corporate Banner
Satellite Banner
Biomolecular Screening
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

Stress-Induced Hormone Primes Brain for PTSD

Published: Wednesday, October 16, 2013
Last Updated: Wednesday, October 16, 2013
Bookmark and Share
MIT study finds that ghrelin, produced during stressful situations, primes the brain for post-traumatic stress disorder.

About a dozen years ago, scientists discovered that a hormone called ghrelin enhances appetite. Dubbed the “hunger hormone,” ghrelin was quickly targeted by drug companies seeking treatments for obesity — none of which have yet panned out.

MIT neuroscientists have now discovered that ghrelin’s role goes far beyond controlling hunger. The researchers found that ghrelin released during chronic stress makes the brain more vulnerable to traumatic events, suggesting that it may predispose people to posttraumatic stress disorder (PTSD).

Drugs that reduce ghrelin levels, originally developed to try to combat obesity, could help protect people who are at high risk for PTSD, such as soldiers serving in war, says Ki Goosens, an assistant professor of brain and cognitive sciences at MIT, and senior author of a paper describing the findings in the Oct. 15 online edition of Molecular Psychiatry.

“Perhaps we could give people who are going to be deployed into an active combat zone a ghrelin vaccine before they go, so they will have a lower incidence of PTSD. That’s exciting because right now there’s nothing given to people to prevent PTSD,” says Goosens, who is also a member of MIT’s McGovern Institute for Brain Research.

Lead author of the paper is Retsina Meyer, a recent MIT PhD recipient. Other authors are McGovern postdoc Anthony Burgos-Robles, graduate student Elizabeth Liu, and McGovern research scientist Susana Correia.

Stress and fear
Stress is a useful response to dangerous situations because it provokes action to escape or fight back. However, when stress is chronic, it can produce anxiety, depression and other mental illnesses.

At MIT, Goosens discovered that one brain structure that is especially critical for generating fear, the amygdala, has a special response to chronic stress. The amygdala produces large amounts of growth hormone during stress, a change that seems not to occur in other brain regions.

In the new paper, Goosens and her colleagues found that the release of the growth hormone in the amygdala is controlled by ghrelin, which is produced primarily in the stomach and travels throughout the body, including the brain.

Ghrelin levels are elevated by chronic stress. In humans, this might be produced by factors such as unemployment, bullying, or loss of a family member. Ghrelin stimulates the secretion of growth hormone from the brain; the effects of growth hormone from the pituitary gland in organs such as the liver and bones have been extensively studied. However, the role of growth hormone in the brain, particularly the amygdala, is not well known.

The researchers found that when rats were given either a drug to stimulate the ghrelin receptor or gene therapy to overexpress growth hormone over a prolonged period, they became much more susceptible to fear than normal rats. Fear was measured by training all of the rats to fear an innocuous, novel tone. While all rats learned to fear the tone, the rats with prolonged increased activity of the ghrelin receptor or overexpression of growth hormone were the most fearful, assessed by how long they froze after hearing the tone. Blocking the cell receptors that interact with ghrelin or growth hormone reduced fear to normal levels in chronically stressed rats.

When rats were exposed to chronic stress over a prolonged period, their circulating ghrelin and amygdalar growth hormone levels also went up, and fearful memories were encoded more strongly. This is similar to what the researchers believe happens in people who suffer from PTSD.

“When you have people with a history of stress who encounter a traumatic event, they are more likely to develop PTSD because that history of stress has altered something about their biology. They have an excessively strong memory of the traumatic event, and that is one of the things that drives their PTSD symptoms,” Goosens says.

New drugs, new targets
Over the last century, scientists have described the hypothalamic-pituitary-adrenal (HPA) axis, which produces adrenaline, cortisol (corticosterone in rats), and other hormones that stimulate “fight or flight” behavior. Since then, stress research has focused almost exclusively on the HPA axis. 

After discovering ghrelin’s role in stress, the MIT researchers suspected that ghrelin was also linked to the HPA axis. However, they were surprised to find that when the rats’ adrenal glands — the source of corticosterone, adrenaline, and noradrenaline — were removed, the animals still became overly fearful when chronically stressed. The authors also showed that repeated ghrelin-receptor stimulation did not trigger release of HPA hormones, and that blockade of the ghrelin receptor did not blunt release of HPA stress hormones. Therefore, the ghrelin-initiated stress pathway appears to act independently of the HPA axis. “That’s important because it gives us a whole new target for stress therapies,” Goosens says.

Pharmaceutical companies have developed at least a dozen possible drug compounds that interfere with ghrelin. Many of these drugs have been found safe for humans, but have not been shown to help people lose weight. The researchers believe these drugs could offer a way to vaccinate people entering stressful situations, or even to treat people who already suffer from PTSD, because ghrelin levels remain high long after the chronic stress ends.

PTSD affects about 7.7 million American adults, including soldiers and victims of crimes, accidents, or natural disasters. About 40 to 50 percent of patients recover within five years, Meyer says, but the rest never get better. 

The researchers hypothesize that the persistent elevation of ghrelin following trauma exposure could be one of the factors that maintain PTSD. “So, could you immediately reverse PTSD? Maybe not, but maybe the ghrelin could get damped down and these people could go through cognitive behavioral therapy, and over time, maybe we can reverse it,” Meyer says.

Working with researchers at Massachusetts General Hospital, Goosens’ lab is now planning to study ghrelin levels in human patients suffering from anxiety and fear disorders. They are also planning a clinical trial of a drug that blocks ghrelin to see if it can prevent relapse of depression. 

The research was funded by the U.S. Army Research Office, the Defense Advanced Research Projects Agency, and the National Institute of Mental Health.


Further Information

Join For Free

Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 3,200+ scientific posters on ePosters
  • More than 4,700+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Why Some Tumors Withstand Treatment
Mechanism uncovered that allows cancer cells to evade targeted therapies.
Thursday, March 17, 2016
Paving the Way for Metastasis
Cancer cells remodel their environment to make it easier to reach nearby blood vessels.
Tuesday, March 15, 2016
Faster Drug Discovery?
Startup develops more cost-effective test for assessing how cells respond to chemicals.
Friday, January 29, 2016
New Device Uses Carbon Nanotubes to Snag Molecules
Nanotube “forest” in a microfluidic channel may help detect rare proteins and viruses.
Tuesday, December 22, 2015
How Cancer Cells Spread
Study offers new targets for drugs that may prevent cancer from spreading.
Thursday, December 17, 2015
Learning About Human Health Using Sewage
PhD student Mariana Matus studies human waste to understand individual and community health.
Thursday, September 17, 2015
Real-Time Data for Cancer Therapy
Biochemical sensor implanted at initial biopsy could allow doctors to better monitor and adjust cancer treatments.
Thursday, August 06, 2015
Bacterial Computing
The “friendly” bacteria inside our digestive systems are being given an upgrade, which may one day allow them to be programmed to detect and ultimately treat diseases such as colon cancer and immune disorders.
Monday, July 13, 2015
Researchers Identify New Target For Anti-Malaria Drugs
Manipulating the permeability of a type of vacuole could help defeat malarial parasites.
Thursday, May 14, 2015
New Way To Turn Genes On
Technique allows rapid, large-scale studies of gene function.
Thursday, December 11, 2014
Microscopic “Walkers” Find Their Way Across Cell Surfaces
Technology could provide a way to deliver probes or drugs to cell structures without outside guidance.
Thursday, October 23, 2014
New Kind of Microscope uses Neutrons
Device could open up new areas of research on materials and biological samples at tiny scales.
Friday, October 04, 2013
New Approach to Global Health Challenges
MIT’s Institute for Medical Engineering and Science brings many tools to the quest for new disease treatments and diagnostic devices.
Friday, September 27, 2013
Microfluidic Platform Gives a Clear Look at a Crucial Step in Cancer Metastasis
A microfluidic platform provides a high-resolution view of a crucial step in cancer metastasis.
Friday, September 27, 2013
Watching Tumors Burst Through a Blood Vessel
A microfluidic platform provides a high-resolution view of a crucial step in cancer metastasis.
Tuesday, September 24, 2013
Scientific News
New Cancer Drug Target in Dual-Function Protein
Scientists at The Scripps Research Institute (TSRI) have identified a protein that launches cancer growth and appears to contribute to higher mortality in breast cancer patients.
Penn State, TB Alliance, and GSK Partner To Discover New Treatments For TB
A new collaboration between TB Alliance, GSK, and scientists in the Eberly College of Science seeks to find new small molecules that can be used to create antibiotics in the fight against tuberculosis (TB).
Molecular Map Provides Clues To Zinc-Related Diseases
Mapping the molecular structure where medicine goes to work is a crucial step toward drug discovery against deadly diseases.
Platelets are the Pathfinders for Leukocyte Extravasation During Inflammation
Findings from the study could help in the prevention and treatment of inflammatory pathologies.
Genetic Research Can Significantly Improve Drug Development
With drug development costs topping $1.2bn (£850 million) to get a single treatment to the point it can be sold and used in the clinic, could genetic analysis save hundreds of millions of dollars?
New Method Opens Door to Development of Many New Medicines
Findings from TSRI reveal human proteins are better drug targets than previously thought.
Diagnosing Systemic Infections Quickly, Reliably
Team develop rapid and specific diagnostic assay that could help physicians decide within an hour whether a patient has a systemic infection and should be hospitalized for aggressive intervention therapy.
What Makes a Good Scientist?
It’s the journey, not just the destination that counts as a scientist when conducting research.
Blood Test That Detects Early Alzheimer’s Disease
A research team, led by Dr. Robert Nagele from Rowan University School of Osteopathic Medicine and Durin Technologies, Inc., has announced the development of a blood test that leverages the body’s immune response system to detect an early stage of Alzheimer’s disease – referred to as the mild cognitive impairment (MCI) stage – with unparalleled accuracy.
A New Approach to Chemical Synthesis
Communesins, originally found in fungus, could hold potential as cancer drugs.
SELECTBIO

SELECTBIO Market Reports
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
3,200+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,700+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FOR FREE!