We next evaluated whether intrahippocampal administration of rimonabant (0.06 μg) would prevent radial arm maze performance deficits caused by either CP-55,940 (0.05 mg/kg) or Δ9-THC (5.6 mg/kg). Both cannabinoid receptor agonists significantly impaired radial arm maze choice accuracy in rats given intrahippocampal infusions of vehicle (see Figure 2A and 2C), as previously reported (Lichtman, et al 1995). Intrahippocampal rimonabant administration completely blocked the memory deficits elicited by systemically administered CP-55,940. A two-way ANOVA revealed a significant interaction between rimonabant and CP-55,940, F (1,54) = 15.24, p < 0.001. Treatment with vehicle + CP-55,940 resulted in significantly more errors than each of the other three drug combinations, indicating that rimonabant blocked the memory disruptive effects of this cannabinoid receptor agonist. In contrast, there were no main effects of rimonabant treatment (p = 0.79) and CP-55,940 (p = 0.25), as well as no interaction between rimonabant and CP-55,940 (p = 0.51) for the maze completion data (Figure 2B).
