Punches derived from single-hemisphere frozen brains were homogenized in methanol (0.3 mL) containing [2H4]-anandamide and [2H8]-2-AG (Cayman Chemicals, Ann Arbor, MI, USA) as internal standards. Protein concentration was determined in the homogenate to normalize samples using the bicinchinonic acid protein assay (Pierce, Rockford, IL). Tissue was collected using the rat brain atlas of Paxinos and Watson (1998) as a guide. The coordinates (relative to bregma) and dimensions of punches collected for selected structures of interest were: prefrontal cortex (+1.7 mm anterior-posterior (AP), +0.5 mm medial-lateral (ML),−3 mm dorsal-ventral (DV); 2 mm × 2 mm; adapted from Marsicano et al. (2002)), piriform cortex (+1.7 mm AP, +4.5 mm ML, −7 mm DV; 2 mm × 1 mm), nucleus accumbens (+1.7 mm AP, +1 mm ML, −3 mm DV; 2 mm × 2 mm), and hippocampus (−2.3 mm AP, +1 mm ML,−4 mm DV; 2 mm × 2 mm). Protein content in punches from the hippocampus, prefrontal cortex, and nucleus accumbens averaged 25–30 μg/sample. Punches from the piriform cortex averaged 10–15 μg protein/sample. Lipids were extracted with chloroform (2 vol) and washed
