Mouse study links cannabinoids to threat avoidance

A study of mice published in Nature Communications reports that cannabinoid exposure intensified defensive reactions to a threatening odor and increased activity in a group of neurons in the central amygdala, a brain region involved in threat responses. The researchers found that these somatostatin-expressing neurons were necessary for the increase in avoidance, but not for increased freezing. The results suggest a possible neural mechanism for cannabinoid-related defensive behavior, but do not establish that cannabis causes anxiety in people. In the experiments, mice received a cannabinoid or a control substance before encountering an odor associated with a predator. Researchers monitored the animals’ behavior and recorded activity in the central amygdala. Mice given cannabinoids showed stronger threat-related defensive responses, including avoiding the odor. The study also reported that the effects on defensive behavior depended on dose. The researchers examined somatostatin neurons, abbreviated as SOM neurons, within the central amygdala. Their activity increased after cannabinoid exposure.