Animals received bilateral infusions of either the CB1 receptor agonist HU-210 (2.5 μg), the CB1 receptor antagonist AM251 (2.5 μg), the FAAH inhibitor URB597 (0.1 or 1.0 μg) or vehicle (DMSO). For studies determining the CB1 receptor dependency of HU-210 and URB597, mixtures of HU-210 and AM251 or URB597 and AM251 were infused using the same doses as above. These doses were chosen based on previous data demonstrating efficacy and selectivity for the target (McLaughlin et al., 2007; Rubino et al., 2008; Lin et al., 2006). A 30-gauge injection cannula extending 0.8 mm below the tips of the guide cannulae was used for infusions. Drug solutions or vehicle were delivered at a rate of 0.5 μL/72 s using a microsyringe pump (Sage Instruments Model 341). Injection cannulae were left in place for an additional 1 min to allow for diffusion. Following infusions, animals were returned to their home cages. For stress induction, animals in studies employing HU-210 or AM251 were left in their cages for 10 min before being put into restrainers, while animals for studies employing URB597 were left
