In a preliminary experiment, we sought to determine an effective intrahippocampal dose of rimonabant that antagonizes the memory disruptive effects of the potent cannabinoid analog CP-55,940 (10 μg/rat) given in the same injection site. CP-55,950 produced a significant increase in the number of re-entry errors (Figure 1A), but did not affect the rate of entry into each arm (Figure 1B). A dose of 0.06 μg rimonabant completely blocked the memory disruptive effects of CP-55,940, as indicated by a significant interaction between rimonabant and CP-55,940 treatment, F (1,32) = 13.59, p < 0.01. Post hoc comparisons showed that microinjections of vehicle + CP-55,940 into the hippocampus elicited significantly more errors than each of the other three treatment conditions. Virtually no re-entry errors were committed by rats in the other three treatment conditions. Neither drug given alone nor in combination affected rate of arm entry, as indicated by no significant interaction between the two drugs (p = 0.51), as well as no significant main effect for either rimonabant treatment (p = 0.79) or CP-55,940 treatment (p = 0.25). The data include rats
