CRH and Anxiety: Furthermore, though in vitro assays indicate that AST is more potent for both CRF1 and CRF2 receptors than is αHelCRF (Hauger et al., 2006), in vivo studies in rats suggest that AST may be less potent in preventing some CRF- and stress-induced and anxiety-related behaviors including CRF-induced locomotor activity (Spina et al., 2000).