Stressed rats treated with cannabinoids, synthetic chemicals that mirror the effects of marijuana, experienced a disappearance in their Post-traumatic Stress Disorder (PTSD) symptoms, new research has found.

In a study published this month in the journal Neuropsychopharmacology, scientists from the Department of Psychology at the University of Haifa, Israel, conducted a two-phase study to determine the impact of marijuana on the development of PTSD and to understand the processes involved in the drug's introduction to the brain.

Studying Rats with PTSD Symptoms

In the first phase, the researchers subjected lab rats to extreme stress which led to the rodents developing PTSD-like symptoms. The rats exhibited increases in startling reflexes, anxiety levels, and inhibitory avoidance. Disruptions in their HPA axis function, the biological mechanism which regulates emotions through interactions between the hypothalamus, pituitary and adrenal glands, were also noted. The animals' physical and physiological reactions to stress mimicked PTSD development in humans.

After inducing PTSD symptoms on the test subjects, lead researcher Irit Akirav, PhD divided the study rats into four groups. The first remained untouched as a control group, and the second, third and fourth groups received a cannabinoid injection 2, 24 and 48 hours respectively post-exposure to a traumatic event.

Treating PTSD

PTSD is an anxiety disorder characterized by increased fear, avoidance, and isolation of people or places related to a trauma. Triggered after having experienced a traumatic event where one's life or that of another has been seriously threatened, injured, or killed, the condition renders sufferers unable to complete daily tasks and manage their lives. Symptoms include recurrent nightmares, flashbacks, angry outbursts, helplessness, and emotional detachment, and are a result of traumas including rape, domestic and child abuse, combat duty, car accidents, and natural disasters.

Traditional treatments for the psychiatric condition include cognitive behavioral therapy and medications known as selective serotonin reuptake inhibitors, or SSRIs. The drugs aim to activate brain neurotransmitters associated with the biological manifestations of the condition.

Rats Treated with Cannabinoids Show Less PTSD Symptoms

At the one-week follow up, the team noted that both the first group, which received no intervention, as well as the last cohort, which received a chemical injection after 48 hours of experiencing a stress-inducing event, continued to exhibit extreme anxiety and PTSD signs.

The researchers, however, did notice a complete disappearance of PTSD-like symptoms among the two other groups of rats, both of whom were treated with the marijuana substance within a shorter time interval after being stressed. The two groups still maintained a high-level of anxiety, with study authors explaining that the treatment prevented the onset of PTSD in the rats without erasing the memory of the traumatic event. The findings also suggest that there is an ideal time following a traumatic experience where such treatment may be most beneficial, they stated.

The second phase of the study involved repeating the first phase, but this time injecting the drug directly into the amygdala, the key brain region for processing emotions and reactions to trauma.

The results in this phase were identical to the first, with the synthetic marijuana preventing the emergence of PTSD symptoms among the same subgroup of rats. Hence, the scientists determined that the brain receptor CB1 mediates the effects of marijuana.

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