Cannabinoid agonists and antagonists modulate lithium-induced conditioned gaping in rats

Considerable evidence indicates that conditioned gaping in rats reflects nausea in this species that does not vomit. A series of experiments evaluated the potential of psychoactive cannabinoid agonists, Delta-9-THC and HU-210, and non-psychoactive cannabinoids, Cannabidiol (CBD) and its dimethylheptyl homolog (CBD-dmh), to interfere with the establishment and the expression of conditioned gaping in rats. All agents attenuated both the establishment and the expression of conditioned gaping. Furthermore, the CB I antagonist, SR-141716, reversed the suppressive effect of HU-210 on conditioned gaping. Finally, SR-141716 potentiated lithium-induced conditioned gaping, suggesting that the endogenous cannabinoid system plays a role in the control of nausea.