Administration of cannabinoids, in the form of synthetic marijuana, blocks the development of post-traumatic stress disorder (PTSD)-like symptoms in rats after they experience a traumatic event, according to a new study conducted at the University of Haifa and published in the journal Neuropsychopharmacology.
“We found that there is a ‘window of opportunity’ during which administering synthetic marijuana helps deal with symptoms simulating PTSD in rats,” said Dr. Irit Akirav of the University of Haifa’s Department of Psychology, who led the study.
The researchers set out for examining how administering cannabinoids (synthetic marijuana) affects the development of PTSD-like symptoms in rats, whose physiological reactions to traumatic and stressful events is similar to human reactions. The study was conducted by Dr. Akirav with research student Eti Ganon-Elazar.
The researchers exposed a group of rats in the first part of the study to extreme stress and observed that the rats did indeed display symptoms resembling PTSD in humans, like 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 — one group was given no marijuana at all; the second was given an injection of marijuana two hours after being exposed to a traumatic event; the third group after 24 hours, and the fourth group after 48 hours.
The researchers examined the rats a week later and found that he group that had not been administered 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 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 Dr. Akirav, who added the results indicate there is a particular window of time during which administering marijuana is effective.
The researchers repeated stage one of experiment in second stage of the study for understanding the bran mechanism that is put into operation during the administering of marijuana. It was found that marijuana blocked development of PTSD symptoms in these cases as well, which helped in concluding that the effect of the marijuana is mediated by a CB1 receptor in the amygdala.
Eti Ganon-Elazar, Irit Akirav. Cannabinoids Prevent the Development of Behavioral and Endocrine Alterations in a Rat Model of Intense Stress. Neuropsychopharmacology, 2011; DOI: 10.1038/npp.2011.204