Pubdate: Tue, 09 Sep 2014
Source: Jerusalem Post (Israel)
Copyright: 2014 The Jerusalem Post
Contact: http://info.jpost.com/C002/Services/Feedback/editors.html
Website: http://www.jpost.com/
Details: http://www.mapinc.org/media/516
Author: Judy Siegel
Page: 7

MARIJUANA PREVENTS PHYSIOLOGICAL, BEHAVIORAL DAMAGE FROM TRAUMA, 
UNIVERSITY OF HAIFA REVEALS

Experiment on Rats May Lead to Ways to Prevent Development of Ptsd in Humans

Giving rats synthetic cannabinoids soon after a traumatic event can 
prevent post-traumatic stress disorder-like symptoms caused by the 
trauma and by reminders of it.

This was discovered by Nachshon Korem and Dr. Irit Akirav of the 
University of Haifa's psychology department, as just published in the 
journal Neuropsychopharmacology.

"The importance of this study is that it contributes to the 
understanding of the brain basis of the positive effect cannabis has 
on PTSD. This thus supports the necessity of performing human trials 
to examine potential ways to prevent the development of PTSD and 
anxiety disorders in response to a traumatic event," the researchers said.

About 9 percent of the population suffer from PTSD; in some groups, 
such as Holocaust survivors, combat soldiers, prisoners, victims of 
assault and citizens in lines of confrontation, the prevalence is even higher.

A common phenomenon among those who suffer from trauma is that 
exposure to a "trauma reminder"  an event that is not essentially 
traumatic but evokes the memory of the experience of the traumatic 
event  can further heighten the negative effects of the trauma. For 
example, for a person who has developed PTSD syndrome as a result of 
Color Red rocket-warning sirens, a trauma reminder can occur 
following a loud car alarm.

In previous studies by Akirav, she discovered that the use of 
cannabinoids within a specific time window after the traumatic event 
occurred reduces PTSD symptoms in rats. In this study, together with 
doctoral student Korem, she aimed to examine whether the use of 
cannabinoids may also moderate the effects of trauma in cases of 
exposure to trauma reminders. The researchers chose rats because of 
their great physiological similarity to humans in the way they 
respond to stressful and traumatic events.

During the first half of the experiment, the rats underwent the 
traumatic event of getting an electric shock and were exposed to 
trauma reminders on the third and fifth days of the trial. After the 
event, and within the time window found in earlier studies, some of 
the rats were injected with a cannabinoid substance. The rats then 
went through extinction procedures for trauma (a conditional 
psychological procedure similar to exposure therapy in humans, the 
purpose of which is to cope with PTSD symptoms).

It became clear that the rats that were injected with the cannabinoid 
substance showed no PTSD symptoms such as impaired extinction 
learning, increased startle response, changes in sensitivity to pain 
and impaired plasticity in the brain's reward center (the nucleus 
accumbens), compared to those not injected with the drug. The 
researchers added that the rats injected with the cannabinoid 
substance showed better results compared to rats who received the 
antidepressant drug sertraline, a substance used with limited success 
in reducing PTSD symptoms.

In fact, for some of the symptoms, the rats that were injected with 
the cannabinoid substance showed behavior similar to that of rats 
exposed to trauma but not exposed to trauma reminders. In other 
words, cannabis made the effects of trauma reminders "disappear."

Once they found the moderating effect of cannabis on behavioral 
aspects, the study examined the neurobiological basis for the 
improvement caused by the drug.

It was found that rats exposed to trauma and trauma reminders showed 
an increase in the expression of two receptors in the brain 
associated with emotional processing  the CB1 receptor, a receptor in 
the brain that cannabinoids bind with, and receptor GR, which is 
associated with exposure to stress. On the other hand, in rats that 
received cannabinoids, the increase in the expression of these two 
receptors was prevented in the hippocampus and prefrontal cortex - 
areas involved in forming and saving traumatic memories.

"The findings of our study suggest that the connectivity within the 
brain's fear circuit changes following trauma, and the administration 
of cannabinoids prevents this change from happening. This study can 
lead to future trials in humans regarding possible ways to prevent 
the development of PTSD and anxiety disorders in response to a 
traumatic event," the researchers concluded.
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MAP posted-by: Jay Bergstrom