et al., 1999; Liu and Weiss, 2002). The ability of N/OFQ to block both stress- and cue-induced relapse therefore raises two distinct possibilities. One is that N/OFQ simply acts at multiple sites in the brain to modulate both aversive and appetitive motivations (Figure 4). Alternatively, it has been suggested that neurocircuitry mediating relapse triggered by stress and drug-associated cues converges on a common final output pathway (Kalivas and Volkow, 2005), and N/OFQ may act beyond that point of convergence.
