side at a dose combination of 10 mg/kg PF3845 and 10 mg/kg anandamide. Although full substitution did not occur, inspection of data for individual subjects revealed that 4 of 7 mice tested with this dose combination distributed greater than 90% of their responses on the THC-associated aperture. Limited supplies of PF3845 prevented testing of a higher dose to determine whether full substitution would occur. In addition, 10 mg/kg PF3845 produces maximal FAAH inhibition in vitro, lasting up to 24 h after i.p. administration (Ahn et al., 2009). When tested in combination with various doses of THC, 10 mg/kg PF3845 failed to shift the THC dose-effect curve (Fig. 2, panel A). In contrast with the complete lack of substitution observed with the FAAH inhibitor PF3845 alone, the MAGL inhibitor JZL184 dose-dependently increased responding on the THC-associated aperture, with a maximum 71% of the responses on the drug-associated side at the 30 mg/kg dose. The partial substitution of 30 mg/kg JZL184 was reversed by 0.3 mg/kg rimonabant [Fig. 2, panel B; F(4,24)=15.67, P<0.05], a dose combination that also significantly suppressed responding compared to vehicle and to 30 mg/kg JZL184 alone [Fig. 2, panel D; F(4,24)=7.29, P<0.05]. Response rates were not significantly decreased
