“…In previous reports, it has been described that administration of N/OFQ (Jenck et al, 1997;Griebel et al, 1999;Gavioli et al, 2002) or the synthetic N/OFQ analogue Ro 64-6198 (Jenck et al, 2000;Wichmann et al, 2000;Dautzenberg et al, 2001) decreased fear-and anxiety-related behaviors in a variety of assays. In fact, when we initially reported that N/OFQ increases circulating ACTH and CORT concentrations in unstressed and mildly stressed rats (Devine et al, 2001), we reconciled our hormonal findings with the published behavioral data (Jenck et al, 1997;Griebel et al, 1999) on the basis that a variety of drugs that are anxiolytic can also increase circulating CORT concentrations in unstressed or mildly stressed rats (Ellis, 1966;Kakihana et al, 1968;Marc and Morselli, 1969;Tabakoff et al, 1978;Rivier et al, 1984;Matheson et al, 1988Matheson et al, , 1997ade Boer et al, 1991).…”