UK researchers report the discovery of a neural mechanism that protects individuals from stress and trauma turning into post-traumatic stress disorder.
Investigators from the University of Exeter Medical School began with the knowledge of the brain’s “plasticity,” its unique capability to adapt to changing environments. Studying mice, they found that stressful events reprogram certain receptors in the amygdala, the brain’s emotional nexus. These receptors then determine how the brain reacts to the next traumatic event.
The receptors (called protease-activated receptor 1 or PAR1) act in the same way as a command center, telling neurons whether they should stop or accelerate their activity.
Normally, PAR1s tell amygdala neurons to remain active and produce vivid emotions. However, after trauma they command these neurons to stop activating and stop producing emotions — protecting the organism from developing uncontrollable fear.
This adaptation helps us to keep our fear under control, and not to develop exaggerated responses to mild or irrelevant fear triggers. For example, someone who may have witnessed a road traffic accident develops a fear of cars or someone who may have had a dog jump up on them as a child now panics when they see another dog.
In the study, researchers used a mouse model in which the PAR1 receptors were genetically de-activated. These animals developed a pathological fear in response to even mild, aversive stimuli.
“The discovery that the same receptor can either awaken neurons or ‘switch them off’ depending on previous trauma and stress experience, adds an entirely new dimension to our knowledge of how the brain operates and emotions are formed,” said study leader Robert Pawlak, M.D., Ph.D.
Pawlak added: “We are now planning to extend our study to investigate if the above mechanisms, or genetic defects of the PAR1 receptor, are responsible for the development of anxiety disorders and depression in human patients.
“There is more work to be done, but the potential for the development of future therapies based on our findings is both exciting and intriguing.”
The study has been published in the journal Molecular Psychiatry.