Medical marijuana is known to ease pain in cancer patients of all ages and is
used for that purpose in Israel and many other countries. Now University of
Haifa researchers, working with rodents, have found that administering cannabis
after a traumatic experience prevents the development of post-traumatic stress
symptoms in a rat model.
They discovered that while the drug does not
erase the traumatic experience, it does prevent the development of post-trauma
symptoms. If clinical studies show that cannabinoids accomplish the same in
humans, they could be boon to Israel, where wars, terror attacks, road accidents
and other traumatic events have often occurred, as well as to the rest of the
Dr. Irit Akirav of the of the university’s psychology department
and colleagues published her findings in the journal
“We found that there is a ‘window of
opportunity’ during which administering synthetic marijuana helps deal with
symptoms simulating post-traumatic stress disorder [PTSD] in rats,” said Akirav,
who led the study. In the study, which she conducted with research student Eti
Ganon-Elazar, the researchers set out to examine how administering cannabinoids
(synthetic marijuana) affects the development of PTSD-like symptoms in rats,
whose physiological reactions to traumatic and stressful events are similar to
In the first part of the study, the researchers exposed
a group of rats to extreme stress and observed that the rats did indeed display
symptoms resembling human PTSD, such as an enhanced startle reflex, impaired
extinction learning and disruption of the negative feedback cycle of the
stress-influenced HPA axis.
The rats were then divided into four groups.
Some were given no marijuana at all; the second group were given a marijuana
injection two hours after being exposed to a traumatic event; the third group
after 24 hours; and the fourth group after 48 hours.
A week later, the
researchers examined the rats and found that the group that had not been given
marijuana and the group that got the injection 48 hours after experiencing
trauma continued to display PTSD symptoms as well as a high level of
By contrast, PTSD symptoms disappeared in the rats that were
given marijuana two or 24 hours after experiencing trauma, even though these
rats had also developed a high level of anxiety.
“This indicates that the
marijuana did not erase the experience of the trauma, but that it specifically
prevented the development of post-trauma symptoms in the rat model,” said
Akirav, who added that the results suggest there is a particular window of time
during which administering marijuana is effective.
Because the human life
span is significantly longer than that of rats, the Haifa psychologist
explained, one could assume that this window of time would be longer for
The second stage of the study sought to understand the brain
mechanism that is put into operation during the administering of marijuana. To
do this, they repeated stage one of the experiment, but after the trauma they
injected the synthetic marijuana directly into the amygdala area of the brain
that is known to be responsible for trauma response. The researchers found that
the marijuana blocked development of PTSD symptoms in these cases as
From this the researchers were able to conclude that the effect of
the marijuana is mediated by a CB1 receptor in the amygdala.
SCIENCES SEMINAR BROUGHT THE BEST Prof. Roger Kornberg of Stanford University,
who was awarded the Nobel Prize in Chemistry in 2006, spent five days in
Jerusalem recently to direct a “School for Life Sciences” at the Hebrew
University of Jerusalem’s Institute for Advanced Studies' School for Life
Sciences that focused on cancer research.
Increased understanding the
molecular basis of cancer diseases has significantly improved the ability of
doctors to treat certain types of the disease and prolong the life of patients –
but many aspects of cancer still remain a mystery. Data gathered by the the
Central Bureau of Statistics in Jerusalem indicate that cancer is now the
number-one killer in Israel; heart disease used to top the list.
“school” presented various achievements in cancer research, numerous research
challenges, innovative treatment approaches and advanced developments in cancer
medication. The classes explained the differences among various types of cancer
– why some can be treated, while in others the research is just beginning – and
why some types of cancer are more complex than others.
The event has
taken place for the past 19 years.
Kornberg, who says the event leads to
the sharing of knowledge and can lead to future cooperation, annually comes to
HU as a guest professor at the faculty of sciences and as an associate of the
biological chemistry department. The 200 participants, most of them Israeli
masters and doctoral students, heard more than two dozen lectures by leading
cancer researchers from here and abroad.
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