BACKGROUND AND PURPOSE
The cannabinoid 1 (CB1) receptor inverse agonists/antagonists, rimonabant (SR141716, SR) and AM251, produce nausea and potentiate toxin-induced nausea by inverse agonism (rather than antagonism) of the CB1 receptor. Here, we evaluated two phytocannabinoids, cannabidivarin (CBDV) and Δ9-tetrahydrocannabivarin (THCV), for their ability to produce these behavioural effect characteristics of CB1 receptor inverse agonism in rats.
In experiment 1, we investigated the potential of THCV and CBDV to produce conditioned gaping (measure of nausea-induced behaviour) in the same manner as SR and AM251. In experiment 2, we investigated the potential of THCV and CBDV to enhance conditioned gaping produced by a toxin in the same manner as CB1 receptor inverse agonists.
SR (10 and 20 mg·kg−1) and AM251 (10 mg·kg−1) produced conditioned gaping; however, THCV (10 or 20 mg·kg−1) and CBDV (10 or 200 mg·kg−1) did not. At a subthreshold dose for producing nausea, SR (2.5 mg·kg−1) enhanced lithium chloride (LiCl)-induced conditioned gaping, whereas Δ9-tetrahydrocannabinol (THC, 2.5 and 10 mg·kg−1), THCV (2.5 or 10 mg·kg−1) and CBDV (2.5 or 200 mg·kg−1) did not; in fact, THC (2.5 and 10 mg·kg−1), THCV (10 mg·kg−1) and CBDV (200 mg·kg−1) suppressed LiCl-induced conditioned gaping, suggesting anti-nausea potential.
CONCLUSIONS AND IMPLICATIONS
The pattern of findings indicates that neither THCV nor CBDV produced a behavioural profile characteristic of CB1 receptor inverse agonists. As well, these compounds may have therapeutic potential in reducing nausea.
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