Cannabinoids can prevent the long-term negative consequences of exposure to severe stress, according to a new study published by the journal Hippocampus, and e-published ahead of print by the U.S. National Institute of Health.
“Exposure to excessive or uncontrolled stress is a major factor associated with various diseases including post-traumatic stress disorder (PTSD)”, begins the study’s abstract. “The consequences of exposure to trauma are affected not only by aspects of the event itself, but also by the frequency and severity of trauma reminders.”
According to researchers; “Several lines of evidence support the role of the endocannabinoid (eCB) system as a modulator of the stress response. In this study we aimed to examine cannabinoids modulation of the long-term effects (i.e., 1 month) of exposure to a traumatic event on memory and plasticity in the hippocampus and amygdala.”
Following exposure to the “shock and reminders model of PTSD in an inhibitory avoidance light-dark apparatus”, rats demonstrated enhanced fear retrieval and impaired inhibitory extinction, impaired hippocampal-dependent short-term memory and enhanced amygdala-dependent conditioned taste aversion memory, among other changes. The cannabinoid CB1/2 receptor agonist WIN55-212,2 – meant to mimic the effects of natural cannabinoids – administered two hours after shock exposure “prevented these opposing effects on hippocampal- and amygdala-dependent processes.”
Moreover, the effects of the agonist were prevented by co-administration of a low dose of the CB1 receptor antagonist AM251, suggesting that the preventing effects of are mediated by CB1 receptors.
In addition; “Exposure to shock and reminders increased CB1 receptor levels in the CA1 and basolateral amygdala (BLA) one month after shock exposure and this increase was also prevented by administering WIN55-212,2 or URB597.”
Taken together, “these findings suggest the involvement of the endocannabinoid system, and specifically CB1 receptors, in the opposite effects of severe stress on memory and plasticity in the hippocampus and amygdala.”
The full study can be found by clicking here.