Researchers induce PTSD symptoms in mice

February 24, 2012 by Bob Yirka, Medical Xpress report
Lab mice

(Medical Xpress) -- Post traumatic stress disorder (PTSD) is a condition in which people find themselves experiencing intense fear following a traumatic experience due to unrelated circumstances. It’s quite common in soldiers returning from the battlefield but can also be found in people that have experienced an assault, abuse or tragedy such as surviving a hurricane or tornado. And because it can persist for years after the initial trauma, those that suffer from it can find their lives seriously disrupted. Because of this, research into ways to treat the condition has been ongoing by both military and civilian entities. Now, a French team of researchers has found, as they describe in their paper published in Science, a way to induce what appears to be PTSD symptoms in mice, a move that could help scientists better understand the chemical processes that go on in the brain in people with the disorder.

To replicate the traumatizing effects of conditions that cause people to experience , the researchers set a group of in a plastic cage where they were subsequently shocked on the feet with an electric probe right after a tone was played. This quite naturally caused them to become conditioned to expect pain upon hearing the tone. To make the experience more heightened, which is a main component of PTSD, the mice were also given a dose of corticosterone (a stress response hormone) injected directly into their hippocampus right after being shocked. In extremely high stress situations, corticosterone levels in the hippocampus (an area of the brain associated with memory) are naturally higher. In a second experiment, they did exactly the same thing, except they omitted the part where the tone was played before the shock.

In testing the mice afterwards, the dose of corticosterone given after the traumatic event seemed to cause confusion as to which thing should be tied to the fear. Some mice who had not heard the tone prior to the shock displayed fear when hearing it nonetheless.

In a wholly different experiment, the team also attempted to induce PTSD symptoms by restraining the mice inside their cage causing stress hormones to be released naturally after the tone and shock were administered and found virtually the same results.

This all suggests, the team writes, that very traumatic and stressful situations cause hormone levels to rise, at least in some mice (and perhaps humans) and that is what leads to PTSD.

The team also found in studying the brains of the mice after the experiment that hippocampus activity levels were lower than normal while the amygdale, a part of the brain involved in processing and emotional memory, showed more.

Explore further: Researchers pinpoint genetic connection to traumatic experience

More information: Glucocorticoids Can Induce PTSD-Like Memory Impairments in Mice, Published Online February 23 2012, Science DOI: 10.1126/science.1207615

ABSTRACT
Post-traumatic stress disorder (PTSD) is characterized by a hypermnesia of the trauma and by a memory impairment that decreases the ability to restrict fear to the appropriate context. Infusion of glucocorticoids in the hippocampus after fear conditioning induces PTSD-like memory impairments and an altered pattern of neural activation in the hippocampal-amygdalar circuit. Mice become unable to identify the context as the right predictor of the threat and show fear responses for a discrete cue non-predicting the threat in normal conditions. These data demonstrate PTSD-like memory impairments in rodents and identify a potential pathophysiological mechanism of this condition.

Related Stories

Researchers pinpoint genetic connection to traumatic experience

February 1, 2012
Rutgers scientists have uncovered genetic clues as to why some mice no longer in danger are still fearful while others are resilient to traumatic experiences – knowledge that could help those suffering with crippling ...

Marijuana blocks PTSD symptoms in rats: study

September 20, 2011
Marijuana administered in a timely fashion could block the development of post-traumatic stress disorder symptoms in rats, a new study conducted at Haifa University has found.

Chronic post-traumatic stress disorder in women linked to history of rape, child abuse

November 29, 2011
A Florida State University clinical psychologist has identified factors that could cause some women with post-traumatic stress disorder (PTSD) to have chronic, persistent symptoms while others recover naturally over time.

Recommended for you

People with prosthetic arms less affected by common illusion

January 22, 2018
People with prosthetic arms or hands do not experience the "size-weight illusion" as strongly as other people, new research shows.

Study of learning and memory problems in OCD helps young people unlock potential at school

January 22, 2018
Adolescents with obsessive-compulsive disorder (OCD) have widespread learning and memory problems, according to research published today. The findings have already been used to assist adolescents with OCD obtain the help ...

Intensive behavior therapy no better than conventional support in treating teenagers with antisocial behavior

January 19, 2018
Research led by UCL has found that intensive and costly multisystemic therapy is no better than conventional therapy in treating teenagers with moderate to severe antisocial behaviour.

Babies' babbling betters brains, language

January 18, 2018
Babies are adept at getting what they need - including an education. New research shows that babies organize mothers' verbal responses, which promotes more effective language instruction, and infant babbling is the key.

College branding makes beer more salient to underage students

January 18, 2018
In recent years, major beer companies have tried to capitalize on the salience of students' university affiliations, unveiling marketing campaigns and products—such as "fan cans," store displays, and billboard ads—that ...

Inherited IQ can increase in early childhood

January 18, 2018
When it comes to intelligence, environment and education matter – more than we think.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.