For biochemical studies, animals were randomly assigned to either basal or stress conditions. For stress conditions, rats were put into a polystyrene tube (diameter 6 cm, length 20 cm) with breathing holes. Tubes were long enough to completely encase the rat and too narrow for turning or other large movements. Rats were left in the tubes for 30 min, then removed and immediately decapitated. Basal animals remained in their home cage until they were decapitated. The amygdala was dissected as previously described (Hill et al., 2006), frozen in liquid nitrogen within 5 min of decapitation and stored at -80 °C until analysis. Trunk blood was collected at the time of decapitation for the analysis of serum corticosterone. One cohort of animals (n = 10) was used to determine brain regional endocannabinoid contents and serum corticosterone levels. Membrane fractions were isolated from brain regions of another cohort of animals (n = 4) and were used for CB1 receptor radioligand binding, CB1 receptor-mediated GTPγS binding and FAAH activity.
