We initially investigated the effects of acute and repeated restraint stress on levels of 2-AG and AEA in the amygdala of mice (Patel et al., 2004; Patel et al., 2005; Patel and Hillard, 2008). With regard to stress effects on 2-AG levels, we observed a progressive increase in tissue 2-AG levels, which was greater after 10, as compared to 5 or 1 consecutive days of restraint stress for 30 minutes per day. We subsequently showed that this increase in 2-AG was observable within the BLA specifically and was also associated with increases in two diacylglycerol precursors of 2-AG (Patel et al., 2009). Similar effects were observed in rats exposed to 10 days of consecutive restraint stress (Hill et al., 2010b). The stress-induced increase in 2-AG clearly demonstrates sensitization, however, the increase in 2-AG levels in response to repeated restraint stress are short-lived. Indeed, 2-AG levels peak at 20 minutes following the start of the 10th restraint exposure and, by 60 minutes, are almost back to control levels (Patel et al., 2009). Similar effects were observed in rats, where 24 hours
