Effect of combined doses of Δ(9)-tetrahydrocannabinol (THC) and cannabidiolic acid (CBDA) on acute and anticipatory nausea using rat (Sprague- Dawley) models of conditioned gaping.
Δ(9)-Tetrahydrocannabinol (THC) and cannabidiolic acid (CBDA) found in cannabis both reduce the distressing symptom of nausea, but their combined effects are not understood. The potential of combined doses of THC and CBDA to reduce acute nausea and anticipatory nausea in rodent models was assessed. For acute nausea, the potential of cannabinoid pretreatment(s) to reduce LiCl-induced nausea paired with saccharin was evaluated in a subsequent drug free taste reactivity test, followed by a taste avoidance test. For anticipatory nausea, the potential of the cannabinoid pretreatment(s) to reduce the expression of LiCl-induced contextually elicited conditioned gaping was evaluated. Combined subthreshold doses of THC (0.01 and 0.1 mgkg) and CBDA (0.01 and 0.1 μgkg) reduced acute nausea. Higher doses of THC (1.0, 10 mgkg) or CBDA (1.0, 10 μgkg) alone, as well as these combined doses also reduced acute nausea. THC (10 mgkg) interfered with conditioned taste avoidance, an effect attenuated by CBDA (10 μgkg). On the other hand, combined subthreshold doses of THC (0.01 and 0.1 mgkg) and CBDA (0.01 and 0.1 μgkg) did not suppress contextually elicited conditioned gaping in a test for anticipatory nausea. However, higher doses of THC (1.0, 10 mgkg) or CBDA (1.0, 10 μgkg) alone, as well as these combined doses, also reduced anticipatory nausea. Only at the highest dose (10 mgkg) did THC impair locomotor activity, but CBDA did not at any dose. Combined subthreshold doses of THCCBDA are particularly effective as a treatment for acute nausea. At higher doses, CBDA may attenuate THC-induced interference with learning.