Effects of cannabidiol and Δ9-tetrahydrocannabinol in the elevated plus maze in mice.
The present study tested the effects of cannabidiol (CBD) alone, Δ-9-tetrahydrocannabinol (THC) alone, and CBD and THC in combination (151 ratio) in the elevated plus maze (EPM), a test useful for the study of anxiety. In dose-response studies, adult, male CD1 mice were injected intraperitoneally with (1) CBD alone (0-96 mgkg), (2) THC alone (0-6.4 mgkg) or (3) CBDTHC in a 151 combination (0.0 0.0 mgkg to 96.0 6.4 mgkg). Diazepam (2.5 mgkg) was also tested as a positive control. It was found that diazepam significantly increased open arm time in the EPM. CBD alone had no significant effect at any dose or injection-test interval. THC alone, however, caused a significant increase in open arm time at 3.2 and 6.4 mgkg - doses which did not affect locomotion as measured by closed-arm entries. The effect of the combination of CBD and THC was not significantly different than the effect of THC alone. CBD alone did not have anxiolytic-like effects. THC had anxiolytic-like effects at nontoxic doses. No interaction between THC and CBD was seen when the two were combined.