A comparison of cannabidiolic acid with other treatments for anticipatory nausea using a rat model of contextually elicited conditioned gaping.
The effectiveness of cannabidiolic acid (CBDA) was compared with other potential treatments for anticipatory nausea (AN), using a rat model of contextually elicited conditioned gaping reactions. The potential of ondansetron (OND), Δ(9)-tetrahydrocannabinol (THC), chlordiazepoxide (CDP), CBDA, and co-administration of CBDA and tetrahydrocannabinolic acid (THCA) to reduce AN and modify locomotor activity was evaluated. Following four pairings of a novel context with lithium chloride (LiCl), the rats were given a test for AN. On the test trial, they received pretreatment injections of the following vehicle, OND (0.1 or 1.0 mgkg), THC (0.5 mgkg), CBDA (0.0001, 0.001, 0.01, 0.1 mgkg or 1.0 mgkg), CDP (1, 5, or 10 mgkg) or co-administration of subthreshold doses of CBDA (0.1 μgkg), and THCA (5 μgkg). Immediately following the AN test trial in all experiments, rats were given a 15 min locomotor activity test. Finally, the potential of CBDA (0.001, 0.01, 0.1, and 1 mgkg) to attenuate conditioned freezing to a shock-paired tone was assessed. THC, CBDA, and CDP, but not OND, reduced contextually elicited gaping reactions. Co-administration of subthreshold doses of CBDA and THCA also suppressed AN, and this effect was blocked by pretreatment with either a cannabinoid receptor 1 (CB1) receptor antagonist or a 5-hydroxytryptamine 1A (5-HT1A) receptor antagonist. CDP (but not CBDA, THC or CBDA and THCA) also suppressed locomotor activity at effective doses. CBDA did not modify the expression of conditioned fear. CBDA has therapeutic potential as a highly potent and selective treatment for AN without psychoactive or locomotor effects.