the relationship between CB-1 receptors and behaviors related to anxiety. Hill and colleagues (2006) examined the effects of administering both a very low (5 µg/kg) and very high (100 µg/kg) dose of the cannabinoid CB1 agonist HU-210 in rats, and reported increased anxiety-like behavior and higher plasma corticosterone levels in animals treated with chronic high but not low dose HU-210. These results suggest that higher cannabinoid doses may result in increased emotionality and sensitization of the stress axis. Finally, Patel and colleagues’ (2005) finding of increased CeA c-Fos expression following the combination of stress and the administration of a CB-1 agonist in mice lends support to the current study findings. The authors conclude that CB-1 receptor activation effectively reduces the threshold at which salient sensory stimuli activate the basolateral amygdala (BLA) –CeA pathway (Katona et al., 2001). This mechanism may account for the finding that subthreshold environmental stress or even normally neutral stimuli can acquire emotional or affective salience during marijuana intoxication (Patel et al., 2005). This may help to explain why individuals who smoke marijuana regularly do not appear to process affective stimuli in the same way as those who do not smoke, even when the stimuli are presented
