The behavioural effects of beta-caryophyllene in zebrafish are mediated by CB2 receptor activity

Abstract

Research into the effects of terpenes has been on the rise as a result of the recent Cannabis legalization in Canada. Cannabis terpenes have shown a diverse array of therapeutic benefits and have potential as treatments for numerous pathological conditions. Recent research has examined the mechanisms of action of terpenes most commonly found in North American cannabis strains. Other cannabis constituents with medicinal properties, such as THC and CBD, have undergone extensive study and are believed to work in the brain through various mechanisms, most notably CB1 and CB2 endocannabinoid receptors. Terpene compounds selectively binding to CB1 and CB2 receptors may have important implications for medicinal and therapeutic applications. For instance, the endocannabinoid system has been shown to potently modulate anxiety in humans, rodents, and zebrafish. The cannabis terpene, Beta-caryophyllene (BCP), has been of particular interest due to its robust anxiolytic and anti-depressant effects in studies with mice and its potential action at CB2 endocannabinoid receptor sites. The present study utilized the open field exploration test to examine the effects of BCP on zebrafish anxiety-like behaviours, as well as its potential action at cannabinoid receptor sites using CB1 and CB2 receptor antagonists rimonabant and AM630, respectively. This study found BCP to have an anxiolytic effect on zebrafish anxiety-like behaviour, whereby, after BCP administration zebrafish spent less time hugging the outer walls of the arena and more time exploring the center zone. When cannabinoid receptor antagonists rimonabant and AM630 were administered prior to BCP exposure, these effects were eliminated by AM630 and not rimonabant. These findings suggest the behavioural effects of BCP on zebrafish anxiety-like behaviour are mediated by its selective preference for CB2 receptor sites.

Faculty Mentor: Dr. Trevor Hamilton