The effect of restraint stress to reduce the tissue content of AEA within the amygdala of the rat is consistent with previous reports in mice (Patel et al., 2005c; Rademacher et al., 2008). Within the current study, the content of AEA within the amygdala determined at the termination of restraint stress was negatively correlated with the magnitude of the corticosterone response to stress within these same animals, indicating a relationship between amygdalar AEA and HPA axis activation by a psychological stressor. Since pharmacological inhibition of FAAH activity within the BLA reduced the corticosterone response to psychological stress, it is likely that AEA content in the BLA plays a role in constraining HPA axis activation, rather than the converse explanation, that the stress-induced reduction in amygdalar AEA is driven by increased levels of glucocorticoids. It is our hypothesis that stress-induced activation of FAAH within the amygdala is an early event in the cascade of signaling processes that ultimately regulate glucocorticoid secretion. This hypothesis is supported by the fact that we have seen reductions in AEA as rapidly as 5 min after
